Perspectives for High-Purity Quartz from European Resources

Abstract

High-purity quartz (HPQ) is a critical raw material for advanced technologies including semiconductors, photovoltaic cells, and optical fibers. This study reviews the geological occurrence, beneficiation routes, and strategic significance of HPQ within the European context. Quartz processing follows a sequential flowsheet of comminution, magnetic separation, flotation, acid leaching, and thermal treatment, designed to remove mineral impurities such as Fe, Al, Ti, and mica. The resulting ultra-high-purity quartz (UHPQ) achieves the chemical and physical specifications required for high-tech industries. Quartz, which is the most common mineral on Earth, can be found in a variety of geological locations such as granitic rocks and pegmatites in the Variscan Belt, metamorphic quartzites, hydrothermal veins, and Pleistocene periglacial and aeolian sediments. Case studies of European deposits demonstrate that geological origin directly influences processing requirements, and that tailored beneficiation strategies are essential to unlock viable resources. To our knowledge, this is the first Europe-focused synthesis that links these findings with the EU Critical Raw Materials Act, the work that emphasizes the potential for domestic HPQ development to strengthen European supply chain resilience, reduce dependence on imports, and support the transition to a green and digital economy.

1. Introduction

High-purity quartz (HPQ), with more than 99.99% SiO₂ content, has risen in value in recent years because it is the source of silicon metal, a key material for high-tech, industrial, and green tech. Without it, the technologies needed for the European sustainability and innovation goals would be held back. Although quartz is the most abundant mineral in the Earth’s crust, only HPQ is suitable for producing silicon metal, and such deposits are relatively rare and geographically concentrated [1]. Silicon metal is produced through a high-temperature process called carbothermic reduction, in which HPQ is combined with a carbon source in electric arc furnaces [2,3]. As a result, metallurgical-grade silicon is produced. It is a key component in making semiconductors, solar panels, and other high-tech applications [3,4]. Silicon is critical in producing photovoltaic (PV) cells for solar panels, with more than 90% of the world’s solar technology depending on silicon-based components [5].

The need for silicon metal is increasing worldwide, especially for semiconductors [6]. Silicon metal plays a crucial role in metallurgy because of its remarkable properties, and the automotive and aerospace industries are just two of the many sectors where those properties shine. Silicon steel gives aluminum–silicon alloys the energy and performance they want to prevail. Silicon metallic is also the bottom fabric for generating siloxanes and silicones, which are used in everything from clinical gadgets to water-resistant coatings to lubricants [7]. This versatility makes silicon metal so valuable [8,9,10,11]. Due to technological and economic constraints, replacing silicon metal remains challenging. Gallium arsenide is more expensive but is not used much in factories today. Also, there is no suitable replacement for silicon in making aluminum and chemicals because it does not lower performance or add much to costs [12,13,14,15,16].

Due to its importance in high-tech industries, the European Union (EU) has added silicon to its list of critical raw materials [17]. The EU aims to lessen dependence on other countries for materials like silicon. This material is not just an uncommon organization product, it is critical for the EU, and its value extends beyond simply economic considerations. In 2022, over 80% of the silicon needed in Europe was imported from China [17]. This makes Europe highly reliant on China, which is especially concerning given the current global supply chain disruptions and political tensions [17]. Over the last decade, Europe’s perception of silicon metal has been modified notably, highlighting its importance. In 2014, silicon metal was included on a list of key materials alongside borates, chromium, coking coal, magnesite, and phosphate rock, all deemed important for economic stability and supply security. Even in 2017, silicon continued to be recognized as a critical resource, indicating that concerns about its availability have persisted.

Despite this, the scenario had transformed significantly by 2020, as silicon metal gained prominence on Europe’s Critical Raw Materials list [18,19]. This variation highlights Europe’s awareness that securing silicon involves more than financial considerations; it is essential for independence, technological progress, and sustainable growth. Silicon has quietly become a cornerstone of Europe’s future, showing that strategic planning extends beyond corporations to influence everyday life and overall stability.

By 2023, its importance was further reinforced as the EU recognized how valuable silicon metal is economically, its limited substitutability, and the growing risks associated with the global supply being concentrated in just a few regions [17,18,19]. The Critical Raw Materials list [18,19] indicates that Europe requires domestic resources of high-purity quartz (HPQ), to improve energy-efficient refining, and less dependence on external suppliers [20]. A stable silicon metallic deliverer is critical to provide the technologies required by means of the EU’s sustainability and innovation goals. This situation highlights that silicon is pivotal in driving economic and environmental progress in the region [19].

Quartz is the most common mineral found in igneous, metamorphic, and sedimentary rocks and in sediments and hydrothermal veins. Quartz deposits include crystal specimens, quartz-forming rocks, vein quartz, and sands. Quartz is usually found in nature alongside other minerals, such as feldspars, micas, clay minerals, calcite, dolomite, sulfide minerals, hematite, and rutile, among others. Its high prevalence in nature is due to its properties: quartz remains chemically unchanged and is highly stable. The formation of quartz deposits is affected by many factors, resulting in various quartz amounts and impurity types. Usually, quartz ores contain multiple impurities, such as other minerals trapped inside, fluids, crystal defects, and hydroxyl impurities [21]. Because of this complexity, the purification process is detailed and involves several phases, including pre-treatment and physical treatment. Separation, chemical treatment, and other techniques are used in advanced processing [22,23].

Existing reviews of HPQ are predominantly global in scope and tend to treat deposit geology, processing technologies, and policy/market context in isolation [21,24,25,26,27]. For Europe, this leaves several gaps: (i) lack of an integrated framework linking deposit-scale attributes (pegmatitic, hydrothermal, metamorphic, sedimentary) to dominant impurity suites and beneficiation/purification routes [24,25]; (ii) limited deposit-specific processing guidance tailored to European ore textures, inclusion densities, and trace-element chemistry [25,28,29]; (iii) few cross-walks from deposit type to processing risks and yields (e.g., microfractures/fluid inclusions, reagent and energy intensity, waste streams) [21,26,30]; (iv) sparse Europe-focused, peer-reviewed datasets compared with market summaries [31,32], contrasted with peer-reviewed European deposit studies [29,33]; and (v) minimal integration with EU priorities (sustainability/ESG, strategic autonomy) [17,18,20].

This review fills in these gaps by bringing together a European-focused analysis that (1) connects different types of deposits to factors that affect how easily they can be separated, like impurities and texture [24,25]; (2) matches these factors with suitable processing methods and their environmental impact [23,27,34,35]; and (3) places the technical findings within the context of the EU’s strategy for critical materials to help prioritize high-priority mineral resources in Europe [17,18].

In addition to providing a geological overview, we assessed exploitation potential based on four key criteria: (i) SiO₂ grade ranges, (ii) purity characteristics (surface films/heavy minerals vs. inclusions vs. lattice-bound), (iii) resource endowment (approximate tonnage and continuity), and (iv) feasible extraction and processing routes. Deposit types were then compared to highlight the most promising options in Europe. This study aimed to identify quartz resources in Europe and evaluate their potential. It provides a foundation for exploring possible HPQ sources and supporting Europe’s efforts toward greater resource independence.

This review differs from prior literature by providing an integrated, Europe-centric assessment of HPQ that maps deposit types (pegmatitic, hydrothermal, metamorphic, sedimentary) to impurity signatures and beneficiation requirements, and it then connects these technical realities to EU strategic-materials policy. To our knowledge, no previous work has combined (i) continent-wide deposit screening, (ii) deposit-specific processing flowsheets and sustainability considerations, and (iii) implications for European raw-material independence in a single framework.

2. Quartz Production and Uses

A distinction can be made between quartz and HPQ. Quartz is found in all types of geological environments and is frequently exploited as silica sands and gravels, whereas in HPQ, the latter is restricted to a few deposits, mostly in igneous pegmatites or hydrothermal veins and other exceptional deposits, such as those from Norwegian quartzite [29]. Quartz can also be transformed into HPQ through purification by treatment.

2.1. Silica Sand and Gravel

The silica sand market is expected to grow within the coming years, with the Asia/Pacific region projected to grow by way of 6% each year until 2027 [31]. In the years ahead, expanding production and construction sports will boom the production of flat glass, building materials, and other commercial silica sand products. Figure 1 represents the world production of silica sand according to the end-user industry. Rapid increases in flat glass production used in electronic screens will support consumption in the glass market.

More people owning cars and more cars being made are leading to a bigger need for silica sand, especially for making flat glass used in vehicles [24]. Also, growth in manufacturing in different regions is likely to boost the foundry industry, which is expected to grow by 6.3% each year until 2027 [36]. Companies that supply silica sand should see more business because of the fabricated metal products for construction, mining, and automotive sectors. This expansion will increase sales of industrial sand used in metal casting molds [37].

The world’s sand and gravel sources are considerable. However, their extraction can be uneconomical due to geographic distribution, environmental regulations, and first-class requirements for precise use. Quartz-wealthy sands and sandstones, the principal assets of industrial silica sand, may be found globally. In Europe, the production of sand and gravel (Figure 2) is primarily carried out in Poland, where about 4.21 billion kilograms were produced in 2023, reflecting a 7.13% increase over the previous year. Germany followed, producing around 801.39 million kilograms. But this was a 23.52% drop. Spain’s production fell a lot, by 80.64%, to 253.03 million kilograms, while Romania had a 3.84% increase, reaching 166.78 million kilograms. Finland had the highest production per person, with 27.26 metric tons per person, a 1.04% increase from the previous year. These materials are usually used for large-scale purposes like construction, making glass, and for foundries. However, their purity is usually no more than about 95%–98% silica, which means they are not good enough for use in high-tech industries that need very pure materials.

2.2. High-Purity Quartz

The estimated global production of silicon in 2024 was ∼9700 kt [38], which includes high-technology industries and other industrial uses. Australia produced 50 kt of silicon in 2022, with all domestic silicon production undertaken by Simcoa, which operates a silicon refinery in Kemerton, Western Australia [39]. For very high-purity silicon (≥99.99%), Australia shipped only ~3768 kg to Europe, but for (<99.99%) purity, compared with Germany, Hamberg (~5292 t) and the Netherlands, Rotterdam(~1695 t).

Quartz is considered HPQ with a high-purity, having a grade of >98.5 wt.%–99 wt.% SiO₂ or even 99.95 wt.% SiO₂ [40]. Pegmatite deposits are the most significant source of HPQ in the world today. The Spruce Pine deposit in the United States provides about 70% of the world’s HPQ [41]. As the price and need for HPQ went up in the 2000s, Sibelco and The Quartz Corp looked again at how profitable it was to mine quartz and other materials. They have obtained HPQ regularly from different pegmatite areas [42]. The value of HPQ depends mostly on how pure the raw, unprocessed quartz is. In 2024, the HPQ capitalization was about USD 29.82 billion. According to recent market analyses, the global HPQ market is predicted to reach approximately USD 29.82 billion in 2024, with an average compound annual growth rate (CAGR) of 6%–7% over the next decade [43]. Semiconductors make up the largest application segment, consuming between 55 and 60% of total HPQ production due to the essential role of ultrapure quartz in wafer manufacturing and microelectronics. Solar photovoltaics are the second-largest consumer, accounting for an estimated 25%–30% of demand, reflecting the rapid growth of renewable energy markets and EU clean energy goals [44]. Specialty glass, optics, and niche applications such as fiber optics, lighting, and laboratory equipment collectively make up the remaining 10%–15% [45]. This breakdown highlights the strategic importance of HPQ not only as an industrial mineral but as a vital raw material supporting digitalization and energy transition. In 2022, the HPQ market was nearly valued at USD 894.6 million and is expected to attain USD 1.5 billion by 2031 [46,47]. Given that HPQ has a vital role in high-tech applications, its strategic significance may surpass its monetary value. The forecast indicates a growing demand for excessive-purity quartz (HPQ), predominantly pushed by the semiconductor and photovoltaic industries. The Australian Motion Plan highlights that, to fulfill the worldwide sun energy necessities, the demand for uncooked quartz feedstock is projected to boom nearly fortyfold by the 12 months of 2050 [46], despite the fact that the supply chain for this essential mineral remains sensitive, prompted by means of worldwide change geopolitics and macroeconomic elements. By 2022, China was answerable for over 80% of the delivery of important materials, inclusive of polysilicon and wafers utilized in sun panels, emphasizing the vital necessity to diversify the entire silicon supply chain, encompassing extraction to manufacturing.

Quartz is used widely in the construction industry in cement and ceramics and in manufacturing silicone compounds, silicon carbide, and glass (Figure 3). Quartz has historically been a mineral of industrial significance, owing to its piezoelectric properties [1,2]. Technological advances have recently increased the demand for highly pure quartz for high-technology applications.

Metallurgical-grade silicon, about 99% pure, is produced through carbothermic reduction of silica [47] (see Figure 3) and is primarily used in aluminum alloy manufacturing and the chemical industry, mainly for producing silicone compounds [24]. In the automotive sector, aluminum silicon alloys are replacing steel or iron in vehicle parts. These alloys are also employed in aerospace, especially in aircraft manufacturing industries, due to their lightweight and corrosion-resistant properties. Metallurgical-grade silicon is the foundation for further refinement in high-technology applications, such as photovoltaics and semiconductors [47,48].

Polycrystalline and monocrystalline silicon are commonly used materials to make photovoltaic cells, which are parts of solar panels that create electricity from sunlight. Solar-grade silicon needs to be at least 6 N pure. About 15 kg of HPQ is required in order to make 1 kg of silicon that works in a photovoltaic cell. Even though silicon makes up only 3 to 4% of a photovoltaic cell’s weight, it costs around 35 to 50% of the total price of a solar panel. Solar is a leading renewable energy source in global decarbonization and a key driver in renewable energy generation in Australia, as the worldwide transition to renewables has caused a rapid increase in demand for photovoltaics.

Semiconductor makers use monocrystalline silicon to make silicon wafers. To keep things clean, they also use special materials like quartz crucibles [49,50]. Pure silicon is a semiconductor, meaning its electrical conductivity increases with temperature increases. By adding tiny amounts of other elements, called dopants, during the manufacturing process, silicon’s conductivity and other properties can be improved. Semiconductors are used in many things, like smartphones, satellites, and quantum computers.

Ultra-high-purity quartz has a purity of 99.997 wt % SiO₂ [51] and is used in the solar panel and semiconductor industries [52,53,54]. It is a high-value, lower-volume product in a growth phase aligned with the expansion of the solar energy sector.

Figure 3 shows HPQ quartz applications, including feedstock for silicon production: carbothermic reduction of silica to metallurgical-grade silicon (siMG); refinement of siMG by Siemens or fluidized Bed reactor (FBR) producing polycrystalline silicon [55]; and conversion into a single crystal using the Czochralski (cZ) process, resulting in monocrystalline silicon. End applications of silica products are shown in purple. Note that this process flow represents the most common methods used to produce high-purity silicon and is not an exhaustive list of all available processes and refinement techniques.

The global supply chain for ferrosilicon (FeSi) and silicon metal (Figure 4) relies on each nation’s access to energy, infrastructure, and export markets. China holds 3,800,000 metric tons of FeSi, while silicon metal production approximates 7,800,000 tons. Russia and Brazil are principal producers of FeSi, whereas Norway and the United States are leaders in silicon metal production, benefiting from cleaner energy sources and advanced infrastructure. Because the demand for sun and semiconductor-grade silicon intensifies, production might shift toward specialized high-purity facilities. FeSi and silicon metal are critical substances derived from quartz, generally applied in metallurgy, electronics, and solar technology. Global production levels fluctuate, influenced by the availability of quartz, energy sources, and industry capacity factors. Russia is a top FeSi producer with around 470,000 metric tons, supporting its steel and foundry sectors and producing about 50,000 metric tons of silicon metal. Brazil has balanced output, producing approximately 200,000 tons of FeSi. The country produces 190,000 tons of silicon (Si) from nearby quartz and hydroelectric power. The U.S., which no longer has FeSi production, concentrates on high-purity silicon metal, with an annual output of approximately 310 million tons for electronics and solar industries. Utilizing its vast hydropower sources, Norway emerges as a main EU manufacturer, with the production of about 180,000 tons of FeSi and 130,000 tons of silicon. Kazakhstan and Malaysia are terrific producers, each contributing about 130,000 lots annually for export functions. France and Iceland are engaged in producing these materials, with France predominantly producing round 90,000 tons of silicon steel intended for commercial enterprise and solar programs. Smaller producers together with Bhutan, India, Poland, and Spain cater to regional demands, specifically within the metallic location. Australia and Canada rely greatly on silicon metallic manufacturing to reinforce the electronics sectors. These manufacturing inclinations imply a transition toward excessive-purity silicon manufacturing, propelled with the aid of the developing call from the renewable power and semi-conductor industries.

2.3. Global Producers and EU Position

Europe holds a crucial but challenging role in the global HPQ value chain. While regional demand remains strong—mainly driven by growing semiconductor capacity and expanding photovoltaic deployment—the continent’s domestic supply of ultra-pure quartz is limited, leading to dependence on high-grade imports (mentioned in

Table 1. Global HPQ producers, EU trade flows, and indicative pricing (2023–2024) [56].

Country	Main Companies	Capacity	EU Trade (2023, HS 250610)	Indicative Pricing (USD/t)	References
United States	Sibelco (Spruce Pine, NC, IOTA®); The Quartz Corp (Spruce Pine, NC)	Sibelco is investing ~USD 200 M to double capacity; TQC also operates in Drag, Norway	EU imports: USD 33.6 M (7153 t)	Ultrapure HPQ > 20,000; crucible-grade 4900–30,800	[56,57,58]
Norway	The Quartz Corp (Drag)	Two refining plants; >USD 35 M upgrades	EU imports: USD 0.53 M (12,660 t)	Ultrapure 2800–5500	[56]
China	Jiangsu Pacific Quartz (Donghai)	New project: 60,000 t/yr HPQ sand, 150,000 t/yr semiconductor-grade	EU imports: USD 2.4 M (1786 t)	Crucible sand: 1750–4900 (outer/inner layers)	[58,59]
Turkey	Multiple, Aydln	n/a (not ultrapure)	EU imports: USD 8.7 M (38,758 t)	Mostly medium-purity 300–600	[56]
Russia	Kyshtym Mining, Kyshytm	n/a	EU imports: USD 1.4 M (221 t)	Medium-purity 400–800	[56]
Brazil	Unimin/Sibelco JV, Jaguaruna	n/a	EU imports: USD 2.3 M (2322 t)	Medium-purity 300–600	[56]
India	Gujarat Mineral Dev. Corp., Ahmedabad	~8–10 kt est.	Limited to regional trade	2000–3500	[60]

) (especially from the U.S. and Norway). (e.g., ~USD 427.6 million market size in 2024, with a 7% CAGR to 2030) [56]. European policy efforts aimed at achieving strategic autonomy in raw materials and promoting circular economy practices open opportunities for local purification, recycling, and downstream value creation. Nonetheless, high energy costs, permitting challenges, and strict purity standards required by advanced electronic and solar applications continue to pose significant obstacles to increasing local HPQ production.

2.4. Evaluation Rules Used

Silica (SiO₂) materials are classified based on their purity into respective grade bands. Metallurgic-grade Si (MG Si) feedstock typically contains some 98.5 wt.%–99.5 wt.% SiO₂, while high-purity quartz (HPQ) precursors range from about 99.0 to 99.9 wt.% SiO₂ prior to encouraged upgrading. The nature of impurities importantly influences the processing methods that are compulsory. Superficial films and the heavy minerals involved are comparatively easier to remove through corrosion or leaching, whereas inclusions and mineralized intergrowths involve more middle-of-the-road methods such as floatation or attractable interval followed by leaching. The most challenging impurities are those that are latticework bound within quartz glass such as Al and Ti, which often take high-temperature treatments or chlorination in combination with leaching. The scale of an resourcefulness endowment fund can vary from low to medium or high, referring to the order of magnitude tunnage useable. Abstraction routes depend on the deposit type, with dredging or wet/dry mining typically used for sedimentary deposits; exclusive quarrying practical to pegmatites and quartzites; and vein mining or quarrying used for hydrothermal quartz. Correspondingly, the processing intensity necessary to achieve desired purity levels can range from low to high.

3. Types of Quartz Deposits in Europe

Quartz can be present in different types of deposits, with the most important being as follows: (1) in magmatic plutonic rocks, (2) pegmatites, (3) hydrothermal veins, (4) metamorphic deposits, (5) and sedimentary deposits.

3.1. Magmatic Quartz

Minerals crystallize from melts in magmas following a sequence according to their melting temperature. Quartz is the last mineral to crystallize. Thus, quartz is present in most magmatic rocks and is especially abundant in the last-formed or granitic rocks associated with other minerals. The later a magmatic rock forms, the more quartz it usually contains.

Granites are abundant in Europe, mainly forming the Variscan Belt across the entire continent. The Variscan Belt extends as far as Romania and Bulgaria, with abundant granitic bodies [61]. The end of the belt is in Turkey, where granitic bodies also occur [62].

The Iberian Massif is located in the westernmost part of Europe. It is made up of granitic rocks from the Variscan orogeny (Figure 5) and runs along the whole western side of the Iberian Peninsula [63]. In some cases, these granites have large grains, and the quartz can be easily separated from the other minerals. One example is the granite from Porriño, in Galicia, on the border between Spain and Portugal. This granite is currently used as an ornamental rock [64].

The Cornubian Batholith in southwest England is a significant granitic intrusion formed during the Variscan orogeny. It features coarse-grained granites rich in quartz, feldspar, and mica [65,66]. The magmatic quartz is notable for its geological and historical significance. It has importance in tin and copper mining.

The French Central Massif has several Variscan granitic bodies, including some late-forming granitic domes with an abundance of pegmatites and rare metal deposits [67]. In addition, Variscan granites occupy an important part of the north-eastern part of the island of Sardinia [68].

In the Bohemian massif area along the Czech–German border, there is a no-table granite suite that, in Sn-W-Li mineralizations, shows similar features to Zinnwald [69]. The area features both magmatic and hydrothermal quartz occurrences. The special features under the cathodoluminescence and trace element pattern of magmatic quartz in the region aid in distinguishing magmatic from hydrothermal genesis [70]. A cathodoluminescence study of magmatic quartz reveals information not only on the nature of the primary conditions for its crystallization but also on further geological processes affecting the granite after its formation [71].

Implications for purity and processing of magmatic granites across the Variscan Belt commonly host coarse quartz that can be physically liberated from feldspar/mica, enabling magnetic/electrostatic sorting and selective flotation; however, magmatic quartz may carry trace-element signatures and intergrowths, so light leaching is sometimes required for high-grade products [21,64,65,70,71]. Cathodoluminescence and trace-element tools help separate magmatic from hydrothermal overprints when designing flowsheets. Overall, achievable purity is moderate—high with moderate processing intensity (crushing/screening → magnetic/electrostatic sorting → targeted flotation ± mild leaching) [27,34].

3.2. Pegmatitic Quartz

Pegmatites are rocks formed in the last stages of magmatic crystallization. Pegmatites are lenticular to tabular bodies that occur in clusters, forming pegmatitic fields, usually associated with a granite body. Pegmatites exhibit a zoned structure, with several concentric zones and a central quartz core [67,72]. Quartz derived from pegmatites can form highly pure large crystals. In Europe, pegmatites are widely distributed (Figure 6). In the Iberian Massif, they are important deposits, often found associated with granites [73]. This region hosts a variety of granitic pegmatites, many of which contain lithium-bearing minerals such as spodumene and petalite. These pegmatites have been the focus of targeted research on their mineral composition, geochemical development, and formation processes, emphasizing their potential as sources of lithium and other rare elements [54]. An extensive list of the pegmatites found in the central part of the Iberian Massif is given in [74]. Among them, the following stand out: those of the Barroso–Alvão pegmatite field in northern Portugal [75] and the Fregeneda–Almendra pegmatite field in Spain [76].

In southern Ireland, many pegmatites are linked to the Leinster granite [77]. In Austria, the Wolfsberg region, part of the Alpine geological complex, is recognized for Alpine-type pegmatites [78]. Further north, the extensive ancient rock regions of Sweden, Finland, and Norway host some of Europe’s oldest pegmatites. These deposits are commonly mined for quartz, feldspar, and rare earth elements. Most of these regions have comparable geological records, including vintage, energetic tectonic areas that help create massive, coarse pegmatite bodies rich in quartz. The Evje–Ivelang district, located in southern Norway, is well-known for its wide granitic pegmatites, which have been mined for quartz, feldspars, and rare minerals. Studies have examined trace factors, which include lithamum, germanium, aluminum, and titanium in quartz obtained from one hundred fifty-five granitic pegmatites. This investigation reveals the extent of melt fractionation and the crystallization temperatures, offering full insight into the petrogenesis of these pegmatites [28].

In Northern Norway, the Tysfjord area contains NYF-type (niobium–ittrium–fluorine) pegmatites distinguished by high-purity, coarse-grained quartz and feldspar. Drilling efforts from the 1970s to the 1990s, along with more recent research, have examined these pegmatites for their potential to supply materials needed for the energy transition, such as rare earth elements and HPQ [79,80].

The Härsbacka mine, a Sweden’s leading quartz mine, extracted a large pegmatite dyke mainly composed of quartz and feldspar. The mine produced about 230,000 tons of quartz before shutting down in 1946. The pegmatite here is notable for its thickness and purity, making it an important historical source of quartz in Europe [81].

Implications for purity and processing of pegmatitic quartz commonly forms from highly fractionated, slowly cooled melts, yielding large, well-developed crystals that contain fewer mineral/fluid inclusions and show limited intergrowth with feldspar and mica compared with vein or metamorphic quartz [28,72,79,80,81]. These traits provide higher starting purities and facilitate physical liberation so that upgrading can follow shorter, cleaner flowsheets crushing/screening, magnetic/electrostatic sorting, limited flotation, and mild leaching rather than repeated aggressive chemical or thermal treatments [34,35]. In Europe, pegmatite fields such as Evje–Iveland and Tysfjord demonstrate coarse HPQ with correspondingly lower reagent/energy demand and reduced waste generation, making them priority feedstocks for HPQ where tonnage and zoning permit [28,79,80,81].

3.3. Hydrothermal Quartz

Hydrothermal quartz is formed from hydrothermal fluids circulating within the Earth’s crust in open spaces where quartz precipitates to form veins. It is an HPQ, although it may contain numerous inclusions of other minerals, such as pyrite, hematite, micas, and other silicates, as well as fluid inclusions [27,82]. Quartz veins are widespread across Europe and are often associated with mineralizing systems (Figure 7) that have many ore deposits.

In Europe, base metal and tungsten deposits are abundant. As tungsten is critical to the EU, several mines exploit this metal. About 285 deposits and occurrences have been reported in Portugal [83], and a high number of deposits occur in Spain. Tungsten can be exploited in different types of deposits. The most important are vein and stockwork, greisen, skarns, and stratabound. Usually, grisen-type and vein-stockwork deposits coexist in the same area.

Two examples that have been exploited for several decades are Mittersill in Austria and Panasqueira in in the Central Iberian Zone, Portugal. This is a greisen-type deposit, formed during the last stages of magmatic crystallisation. Due to high fluid pressure, a large number of quartz-filled veins developed in the apical part of a granitic intrusion. The mineralization consists of a dense swarm of sub-horizontal quartz veins [84], usually between 20 cm and 1 m wide, hosted mainly by schists. Another vital deposit of this type, located in the Central Iberian area, in this case in Spain, is that of La Parrilla, which has promising quantities of quartz. Greisen deposits are related to the development of fractures that occur near or in the apical parts of the granitic intrusions during their crystallization. These fissures are frequently filled with quartz and ore minerals as W-ores. This type of deposit accounts for more than 50% of world tungsten production [85]. Scheelite wolframite is commonly the principal tungsten ore, but ferberite and sheelite are the main minerals in some deposits.

Skarn deposits mentioned in Figure 8 comprised roughly 30% of global tungsten production in 1986 [85]. There are a large number of these in Western Europe [86]. Los Santos is an open-pit scheelite-bearing skarn deposit located 50 km from Salamanca; it has been extensively studied [87]. W-skarns of interest are Salau and Costabonne in the French Pyrenees and Gelbe Birke in Germany, among others [86].

Epithermal base metal and gold deposits are other possible sources of hydrothermal quartz. One of the most important is the Mokrsko Variscan gold deposit in the Bohemian Massif, Czech Republic, consisting of a 200 m thick assemblage of densely spaced, several mm thick, lamellar quartz veins [88]. Some outstanding deposits are found in the Carpathians, such as Baia Mare in Romania [89]; Nová Baňa, Slovakia [90]; Kremnica; Rozalia; and Biely Vrchy [91].

Several epithermal deposits occur in Italy, such as the Au deposits of Furtei and Osilo in Sardinia and Larderello, Amiata, and Latera, in southern Tuscany [92]. The Rodalquilar deposit, in the Cabo de Gata, Southeast Spain, was a vital mineral deposit of low-sulfidation Pb-Zn-(Cu-Ag-Au) quartz veins and high-sulfidation Au-(Cu-Te-Sn) ores [93]. As a result of its exploitation, extensive tailing dumps with an extremely high quartz content remain in the field.

France has several epithermal deposits. The French Massif Central exploits chalcedony from alteration processes produced by epithermal fluids. It consists of three microcrystalline quartz facies: black chalcedony, locally rich in pyrite; grey-brown chalcedony; and white chalcedony [94].

The Enåsen gold deposit in central Sweden is a metamorphosed, Paleoproterozoic analogue to fanerozoic high-sulfidation epithermal Au deposits. The ores are chalcopyrite and gold, and the deposit is hosted by quartz-feldspar and quartz-mica gneisses [95].

Implications for the purity and processing of hydrothermal vein quartz involve achieving high purity where crystals are massive and inclusion density is low, enabling shorter flowsheets (sorting with limited leaching); however, typical impurity carriers—fluid inclusions, sulfides/Fe-oxides, mica/feldspar intergrowths, and lattice-bound Al/Ti—each require specific treatments. Fluid inclusions (H₂O–CO₂) cause bubble and optical defects during melting; the preferred mitigation is calcination followed by water-quenching to rupture inclusions, then acid leaching to remove newly exposed impurities [30,82]. Where sulfides/Fe phases (e.g., pyrite, hematite, pyrrhotite) are present, magnetic/electrostatic separation and/or flotation are required before leaching [24,34]. Intergrowth with feldspar/mica is handled by selective flotation using appropriate silicate collector systems [34,96]. When trace Al/Ti are lattice-bound, achieving ultra-low impurity levels may necessitate stronger leach chemistries or chlorination-assisted roasting. In European greisen/stockwork W systems (e.g., Panasqueira, Mittersill), paragenesis and alteration mapping should occur before flowsheet selection to predict inclusion density and sulfide overprint—factors that differentiate beneficial (short) circuits from challenging (long, reagent-intensive) ones [83,84,93,94,95].

3.4. Metamorphic Deposits

Metamorphic deposits include quartzites and metamorphic remobilizations formed under high-pressure and high-temperature conditions, often resulting in high-density, hard quartz with some impurities like iron oxides, feldspars, and clay minerals [25,97]. Metamorphic quartz is found in many parts of Europe, especially in areas shaped by mountain-building events from the Paleozoic and Mesozoic eras, like the Variscan and Alpine orogenies. These quartz deposits are usually found in metamorphic rocks such as quartzite, gneiss, and schist, and they often appear near critical tectonic zones [98,99].

In the Rhenish Massif in western Germany, quartz veins form because of processes linked to widespread metamorphism and the interaction between rocks and fluids during the Variscan mountain-building period [100].

Another big area is the Bohemian Massif, which covers parts of the Czech Republic, Germany, and Austria. This region has high-grade metamorphic rock areas with familiar quartzite and quartz-rich gneisses. Some researchers [26] found a lot of metamorphic activity here, connecting the growth of quartz to multiple tectonic and heating events during the Variscan mountain-building period. These rocks reflect prolonged crustal evolution, with quartz crystallization occurring during amphibolite to granulite facies metamorphism.

Norway has many big quartzite deposits formed under medium to high heat and pressure, mainly during the Proterozoic and Caledonian mountain-building events. One of the most important is the Tana quartzite in Finnmark. It is a thick, natural quartzite from historic sandstone from the Proterozoic technology. This form of quartzite is heavily mined to make silicon steel and ferrosilicon. In southeastern Norway, the Solør location has fine-grained quartzites that contain kyanite, found at Gullsteinberget and Knøsberget [100]. These deposits formed under high-pressure, medium-temperature conditions typical of the amphibolite facies. They include minerals such as quartz, kyanite, muscovite, and feldspar. While these rocks could serve as a source of high-purity silica, processing them is challenging because of the grain size and accessory minerals. Similar kyanite rocks are found mentioned in Figure 9 in northern Norway at Sørmbua and Kjeksberget in Hedmark, Skjomen, and Nasafjell. These quartzites illustrate a complex metamorphic history and hold promising but technically demanding resources for future industrial applications.

Implications for purity and processing metamorphic quartzites across Norway and Central Europe can attain very high SiO₂ levels, but structural defects and accessory minerals (Fe oxides, feldspar, clays; locally kyanite-bearing fine grains) complicate upgrading [98,99,100]. Coarse, clean quartzites (e.g., Tana) are promising for high-end uses, whereas fine-grained/kyanite-bearing types increase comminution losses and reagent/energy needs; expected flowsheets are more energy- and chemistry-intensive than for pegmatites (deep grinding, magnetic separation, advanced leaching/thermal steps) [27,34,101].

3.5. Sedimentary Quartz

Sedimentary quartz deposits include sandstones and quartz sands that form when older rocks are worn down by erosion.

The Elbe Sandstone, dating from the Cretaceous period, is located in Saxony, Germany, and northern Bohemia, the Czech Republic. It is one of the most studied rock formations. Those quartz-wealthy sandstones, known as diagenesis, undergo modifications over the years and are located in some parts of Europe. They shape a sedimentary belt spanning several intervals, especially during the Pleistocene. This belt consists of environments formed by glaciers, rivers, wind, and shallow seas, stretching from Western to Central Europe.

The conditions contributed to the rocks’ increased strength, making them suitable for creation and restoration. Another tremendous kind is the Jotnian sandstone in the Baltic area, extensively in Sweden and Finland, which is related to Mesoproterozoic technology. These reddish, specifically quartz rocks were fashioned on land. Because they have undergone minimal alteration, they are treasured for their place in analyzing early terrestrial geological tactics [102,103].

Quartz-rich rocks are common throughout Europe and form a sedimentary area that stretches from the west to the north and central parts of the continent, mainly formed during the Pleistocene. Glaciers, rivers, wind, and shallow seas formed these rocks. They played a role in creating metamorphic quartzite and show how Pleistocene periglacial processes helped build up quartz sands in Western Europe. The study [104] focuses on the aeolian and cryogenic reworking of quartz sediments in Central and Eastern Europe. Similarly, the sources [105,106] document large deposits of quartz sand in the lowlands of the Netherlands and Germany, primarily resulting from glaciofluvial and riverine processes over time. Quartz-rich sandstones from Central Europe are used in construction because they are high-quality and easy to find, according to source [107]. These findings show a continuous area of sedimentary quartz deposits across Europe, which helps explain where much of the continent’s HPQ comes from.

In northern Poland, high-purity silica sands from the Tertiary and Cretaceous periods are essential for making glass. These sands mainly have smooth, rounded quartz grains. Studies of the sand show they were formed in river and shallow sea environments, and the grains are well-sorted [108]. Furthermore, fluvial terraces along the Guadalquivir River in southern Spain also supply quartz-rich sediments from upstream bedrock. These sediments assist scientists in understanding how climate and landforms evolved during the Pleistocene [109,110]. These examples show how crucial quartz-based sediment systems are for the economy and learning about past environments in Europe.

Implications for purity and processing of well-sorted silica sands and quartz sandstones (Elbe, Jotnian; high-purity Polish sands) offer good baseline purity and large quantities, but grains often have surface coatings or weathering films [102,103,104,105,106,107,108]. Therefore, surface-focused treatments (scrubbing/attrition, desliming) combined with acid leaching are most effective; extensive bulk purification is generally unnecessary. Processing suitability is high for glass-grade products and selected HPQ precursors, depending on coatings and heavy-mineral content [27,34,35].

3.6. Case Studies

Case Study 1: Evje–Iveland Pegmatites, Norway

The Evje–Iveland pegmatite field in (Table 2) southern Norway is renowned for its large feldspar–quartz–mica pegmatites. These deposits contain significant quartz veins and lenses with relatively low levels of harmful impurities such as Fe and Ti oxides [28]. Historically, mining mainly focused on feldspar and rare minerals, but recent research has emphasized the potential of the quartz fraction for high-purity applications. Beneficiation studies have shown that a combination of hand sorting, magnetic separation, and acid leaching can produce quartz concentrates exceeding 99.9% SiO₂, with additional potential for HPQ feedstock after advanced refining [111]. The close proximity to established HPQ refining facilities in Norway [112] further increases the strategic importance of this district.

Case Study 2: Panasqueira Greisen Veins, Portugal

The Panasqueira mine in central Portugal (Table 2) is one of Europe’s most renowned tungsten deposits, but its extensive quartz–muscovite–topaz greisen veins also serve as a major source of quartz [113]. Although quartz has traditionally been seen as a gangue mineral here, detailed geochemical analysis shows that parts of the veins contain low levels of Fe, Al, and Ti, making them good candidates for beneficiation studies [114]. Pilot flotation and leaching tests have demonstrated that high-purity quartz products can be produced from Panasqueira quartz, emphasizing the potential to revalorize by-products from ongoing tungsten operations. This supports EU circular economy goals by converting a waste stream into a strategic raw material.

Together, these case studies illustrate how both pegmatite-hosted and greisen-related quartz deposits can contribute to Europe’s HPQ supply, complementing imports from the U.S. and Norway.

Table 2. Comparative case studies of European quartz deposits relevant to HPQ [111,114].

Parameter	Evje–Iveland Pegmatites (Norway)	Panasqueira Greisen Veins (Portugal)
Deposit type	Feldspar–quartz–mica pegmatite field	Quartz–muscovite–topaz greisen veins in a tungsten deposit
Geological age	Precambrian pegmatites	Variscan hydrothermal system
Primary minerals	Quartz, feldspar, mica	Quartz, muscovite, topaz, wolframite
Quartz characteristics	Coarse-grained, relatively low Fe/Ti impurities	Fine- to medium-grained, low Fe/Al/Ti
Historic mining focus	Feldspar and rare mineral extraction	Tungsten (wolframite); quartz treated as gangue
Beneficiation studies	Magnetic separation + acid leaching → quartz > 99.9% SiO2	Flotation + acid leaching → upgraded quartz suitable for high-purity trials
HPQ potential	Proximity to Norway’s drag refining plants enhances viability	By-product valorization aligns with EU circular economy goals
Strategic relevance	Possible domestic European HPQ feedstock	Adds value to waste streams from active tungsten mine

Table 2. Comparative case studies of European quartz deposits relevant to HPQ [111,114].

Parameter	Evje–Iveland Pegmatites (Norway)	Panasqueira Greisen Veins (Portugal)
Deposit type	Feldspar–quartz–mica pegmatite field	Quartz–muscovite–topaz greisen veins in a tungsten deposit
Geological age	Precambrian pegmatites	Variscan hydrothermal system
Primary minerals	Quartz, feldspar, mica	Quartz, muscovite, topaz, wolframite
Quartz characteristics	Coarse-grained, relatively low Fe/Ti impurities	Fine- to medium-grained, low Fe/Al/Ti
Historic mining focus	Feldspar and rare mineral extraction	Tungsten (wolframite); quartz treated as gangue
Beneficiation studies	Magnetic separation + acid leaching → quartz > 99.9% SiO2	Flotation + acid leaching → upgraded quartz suitable for high-purity trials
HPQ potential	Proximity to Norway’s drag refining plants enhances viability	By-product valorization aligns with EU circular economy goals
Strategic relevance	Possible domestic European HPQ feedstock	Adds value to waste streams from active tungsten mine

4. Quartz Purification Methods

4.1. Extraction Methods

High-purity quartz (HPQ) is initially produced through selective open-pit or underground mining of pegmatites and vein deposits. Precise geological mapping and controlled blasting are used to minimize contamination from feldspar, mica, and other gangue minerals. The mined quartz then undergoes hand sorting and optical sorting to remove visible impurities and discolorations [115,116,117,118,119]. Contamination control is vital at this stage; therefore, low-iron equipment and selective block recovery methods (such as diamond wire cutting) are often used [120].

In the beneficiation stage, crushing and grinding are used to produce particles with a controlled size distribution. Next, magnetic separation removes iron-rich impurities, while froth flotation separates quartz from feldspar and mica by exploiting differences in surface chemistry. Additional chemical purification steps are necessary to achieve electronic- and solar-grade purities (>99.995% SiO₂). These steps include acid leaching (using HF, HCl, or H₂SO₄) to dissolve trace oxides of Fe, Al, and Ti, as well as thermal treatment at 800–1000 °C to volatilize residual impurities and repair structural defects. Advanced purification may also involve chlorination, roasting, or plasma techniques to reach ultra-high purities required for semiconductor crucibles. Together, these mining, beneficiation, and refining steps ensure the production of ultrapure quartz feedstock suitable for semiconductors, photovoltaics, specialty glasses, and optical fibers.

Beyond mechanical beneficiation and chemical leaching, high-temperature extraction methods are essential for achieving ultra-high-purity grades (>6 N, 99.9999% SiO₂). These processes leverage the thermodynamic behavior of silica and its impurities. Carbothermal reduction smelting occurs at temperatures above 1800–2000 °C, where silica reacts with carbonaceous reductants according to the strongly negative Gibbs free energy at these temperatures, which makes the reaction thermodynamically favorable [121]. Careful control of the furnace atmosphere and residence time is necessary to minimize the formation of silicon carbide (SiC) inclusions.

Metallic impurities such as Al, Fe, and Ti oxides are specifically volatilized at temperatures of 1000 °C or higher. This process also anneals lattice defects in quartz, improving the structural stability of semiconductor crucibles [122]. In plasma purification and chlorination roasting, advanced techniques utilize plasma arcs or chlorination at high temperatures to selectively eliminate trace impurities with lower reagent usage [123]. Plasma heating (>3000 °C) allows for the rapid volatilization of refractory oxides, while chlorination aids in removing alkalis and transition metals. Consequently, although initial feedstock is prepared through conventional mining and beneficiation, and high-temperature extraction and refining are crucial for reaching the extreme purity levels required in the semiconductor and photovoltaic industries. High-temperature quartz extraction involves reducing SiO₂ at elevated temperatures, usually with carbon-based reductants. The main thermodynamic pathway can be summarized as

SiO₂ (s) + 2C (s) → Si (l) + 2CO (g).

The Gibbs free energy for this reduction drops further below zero above 1800 °C, showing that high temperatures are essential for the reaction to occur spontaneously [121]. During industrial smelting, furnace temperatures are kept between 1850 and 2000 °C, with controlled oxygen partial pressures to promote CO formation and reduce SiC inclusions. Key process parameters such as furnace atmosphere, reductant type, and residence time collectively determine the yield and impurity levels.

In hydrometallurgical flowsheets, quartz purification mainly involves the selective removal of impurities like Fe, Al, and Ti oxides. Acid leaching using HF, HCl, or H₂SO₄ occurs under Eh–pH conditions designed to stabilize silica and dissolve metallic oxides. For example, Fe³⁺ ions are soluble in oxidizing, acidic conditions, while TiO₂ requires fluoride complexation [122]. An Eh–pH diagram (Figure 10) shows the stability zone of quartz compared to soluble Fe³⁺/Fe²⁺ and Al³⁺ species, indicating that optimal leaching happens below pH 2 and above +0.5 V (SHE) [124]. This thermodynamic insight helps remove impurities while limiting silica dissolution.

Therefore, high-temperature smelting and hydrometallurgical purification depend on an exact balance of thermodynamic driving forces. Smelting uses strongly negative ΔG° at high temperatures to break down silica, while hydrometallurgy uses acid–redox equilibria to selectively dissolve impurity oxides without disrupting the quartz structure.

4.2. The Main Purification Process of Quartz Sand

Quartz purification methods depend on where the quartz comes from because the way the crystals are structured can differ based on their origin [101]. Quartz minerals have over 15 crystal structures, such as tridymite, hexagonal quartz, coesite, stishovite, and amorphous quartz. When heated, quartz can change its structure at specific temperatures, such as beta-quartz at 573 °C, tridymite at 870 °C, and beta-cristobalite at 1470 °C. These transformations influence quartz’s purifiability. The physical and chemical inclinations, impurities, and different traits of quartz affect how properly the purification strategies work. Even when it is cooled and solidified quickly, it creates a form that helps iron removal the usage of acid. However, some research suggests that adjustments inside the tri-dymite and hexagonal quartz systems do not enhance the purification much [26]. From the viewpoint of quartz ore processing mineralogy, preparing HPQ requires combining multiple purification techniques because of the variety and complexity of impurities in the ore. This complexity makes the processing flow more intricate. The usual process for producing HPQ includes (i) pretreatment steps like crushing, scrubbing, desliming, screening, and grinding; (ii) physical separation methods, such as radiometric sorting, dense media separation, gravity separation, magnetic–electric separation, and flotation (physicochemical process); (iii) chemical treatments, such as (iv) advanced treatments, including vacuum refining, roasting, and chlorination; and (iv) calcination, water quenching, and leaching [34,35,96]. The principles, functions, and characteristics of conventional purification methods are outlined Figure 11. Research on purification techniques mainly concentrates on the following physical and chemical processes because the pre-treatment procedures are relatively simple.

Research on cleaning quartz across Europe is focused on creating new and better ways to obtain pure quartz, which is very important for making advanced materials, electronics, and solar products. The main topics being studied are as follows: (1) new cleaning methods, which use chemicals, heat, and plasma to get rid of impurities such as iron, titanium, and aluminum; (2) eco-friendly approaches, which focus on making the process better for the environment by using fewer harmful substances and saving energy; (3) precision and automation, which uses AI and machine learning to improve control and accuracy; and (4) quality control and standards for materials like quartz, feldspar, and rare minerals. Scientists also look at small amounts of elements like lithium, germanium, aluminum, and titanium in quartz from 155 granitic pegmatites to understand how magma changes and crystals form. In northern Norway, the Tysfjord region hosts NYF-type pegmatites containing HPQ and feldspar. Drilling from the 1970s to 1990s, along with recent research, evaluates their potential for rare earth elements and HPQ for energy use. The Härsbacka mine, once Sweden’s leading quartz source, helped establish standards for HPQ in applications such as semiconductors.

Quartz processing (Figure 12) usually begins with comminution, where run-of-mine quartz is crushed and milled to release mineral particles, followed by classification to remove slimes. The material is then subjected to magnetic separation, where low- and high-intensity magnets eliminate iron oxides and weakly magnetic titanium-bearing impurities. Next, flotation is used to selectively remove mica, feldspar, and iron-bearing silicates, improving concentrate quality. The cleaned quartz goes through acid leaching with HCl, H₂O₂, or HF solutions to dissolve trace metallic impurities like Fe, Al, and Ti. Finally, the product undergoes thermal treatment (500–900 °C or plasma-based processes) to volatilize residual contaminants, producing ultra-high-purity quartz (UHPQ) suitable for high-tech applications such as semiconductors, solar cells, and optical devices.

4.2.1. Deposit-Specific Suitability of Purification Methods

Magmatic quartz (granites): Coarse grains but more frequent feldspar/mica intergrowths and trace-element signatures than pegmatites; baseline purity moderate–high. The best results come from a flowsheet of crushing/screening, followed by magnetic/electrostatic sorting (removing Fe-oxides/feldspars), optionally selective flotation, and light leaching as needed [27,34,64,65,70].

Pegmatitic quartz: Large, well-formed crystals with low inclusion density and limited intergrowth produce high baseline purity. The most effective methods are liberation combined with optical, magnetic, or electrostatic sorting, with minimal flotation and gentle acid leaching; intensive chemical or thermal processes are generally unnecessary, resulting in a relatively low environmental impact [25,27,28,34,72].

Hydrothermal quartz (vein/greisen/epithermal): Purity potential is high but commonly affected by fluid inclusions and sulfide/Fe-oxide overprints. Preferred sequence: flotation (sulfides/silicates) and magnetic/electrostatic separation (Fe phases), followed by acid leaching; add calcination–water quench when inclusion density is problematic, and employing chlorination-assisted roasting for lattice-bound Al/Ti when ultra-low impurities are necessary [23,27,30,34,82,84,93].

Metamorphic quartzites: These quartz sources have a high SiO₂ potential, but often they contain fine-grained kyanite with structurally bound defects and accessory Fe-oxides, feldspars, and clays. Then, the surface cleaning alone is insufficient; most effective are deeper comminution to liberate fine intergrowths, high-intensity magnetic separation, and stronger leach chemistries (HF/HCl/H₂SO₄) and/or thermal steps (calcination; in some cases, chlorination/vacuum/plasma for ultra-high purity). Expect higher energy/reagent demand and yield loss from over-grinding [27,34,98,99,100,101].

Sedimentary quartz (silica sands/sandstones): Large tonnages with good baseline purity; impurities are dominated by grain-surface coatings and heavy-mineral fines rather than lattice defects. Most effective are scrubbing and attrition, desliming, and gravity/magnetic removal of heavies, then acid leaching to remove iron films; extensive bulk purification is rarely needed—hence, surface-focused flows outperform deep thermal or strong-leach routes here (in contrast to metamorphic quartzites) [27,34,103,104,105].

Why methods differ by deposit type:

The decisive factor is where the impurities reside: (i) on grain surfaces (sedimentary deposits follows attrition/desliming/acid leach); (ii) in intergrowths (magmatic/metamorphic deposits depends on comminution + magnetic/electrostatic + flotation); (iii) in fluid inclusions and sulfide overprints (hydrothermal deposits depends upon flotation + magnetic/electrostatic + calcination–quench + leach); or (iv) largely absent (pegmatitic depends on light sorting + mild leach). This mapping aligns with the Section 4 framework (pretreatment; gravity/magnetic/electrostatic separation; flotation as a physico-chemical step; calcination–quenching; acid/chlorination leaching) and supports deposit-specific flowsheet design [23,24,25,27,30,34,101].

Sedimentary basins and quartzite belts provide ample, continuous resources with established extraction (dredging; drill-blast quarrying). Pegmatite and hydrothermal districts are node-rich but discontinuous, requiring selective quarrying/vein mining and strict QA/QC. Matching extraction and impurity style reduce processing intensity and risk.

4.2.2. Waste Management

Waste management and water control are essential challenges in HPQ processing. Flotation of quartz from feldspar and mica, along with other gangue minerals, produces slimes (<30 µm) characterized by a high specific surface area, which increases reagent adsorption and can cause long-term instability of tailings [125]. Methods such as dry stacking, paste thickening, and selective reprocessing for feldspar recovery can reduce environmental impacts and improve material recovery [96]. Proper water management is equally important, as beneficiation circuits often operate with high pulp densities and depend on efficient gas dispersion. Flotation and magnetic separation of HPQ generate fine tailings rich in feldspar, mica, and quartz, which may show geochemical instability over time [126]. Technologies like dry stacking and paste thickening help lower seepage risks and land disturbance [127]. Advanced water recirculation systems, including high-efficiency thickeners, dissolved air flotation, and membrane technologies (UF/RO), are increasingly adopted to reduce freshwater use [128]. These methods also support compliance with the EU Water Framework Directive (2000/60/EC) and the Mining Waste Directive (2006/21/EC), aiding HPQ production in meeting the EU Green Deal’s sustainability and resource efficiency goals [129]. Closed-loop recycling systems using high-capacity thickeners, clarifiers, and membranes can cut freshwater consumption by over 70% [130]. To keep flotation selectivity with recycled water, ongoing monitoring of dissolved silica, ionic strength, and residual reagents is essential [96]. Implementing these strategies ensures that HPQ processing aligns with EU environmental policies and advances the broader sustainability objectives of the EU Green Deal.

4.2.3. Sustainability Impacts

Sustainability in HPQ processing can be assessed using life-cycle assessment (LCA) principles, emphasizing key environmental impact categories such as energy demand, greenhouse gas (GHG) emissions, water usage, and waste production. Each processing route has its own environmental challenges.

• Mining and comminution—Energy-intensive blasting and crushing represent up to 40%–50% of total energy use in mineral processing LCAs [131]. Dust and land disturbance contribute to ecosystem impacts.
• Magnetic separation and flotation—While less energy-intensive, these stages require reagents. Collector and frother usage increase the chemical footprint, with indirect GHG emissions linked to reagent manufacture [96,132].
• Acid leaching—Hydrometallurgical purification contributes most to water consumption and chemical waste, especially with HF- and HCl-based systems. LCAs of comparable leaching processes report acid effluent volumes of 1–2 m³ per ton of concentrate, highlighting the importance of recycling circuits [133].
• Thermal and high-temperature processing—High-temperature refining (>1800 °C) is the dominant contributor to carbon footprint, with electricity consumption translating into 3–5 t CO₂-eq per ton of ultrapure quartz depending on the energy mix [134,135]. Plasma purification, while more selective, may increase electricity use but reduce chemical waste.

These comparisons demonstrate trade-offs between different processing methods: chemical-intensive flowsheets tend to use more water and produce more waste, while high-temperature processes generally consume more energy and have larger carbon footprints. Using closed-loop water systems, renewable electricity, and circular economy practices such as reprocessing tailings and recycling quartz crucibles from PV and semiconductor industries can significantly reduce environmental impacts. Future research should focus on developing comprehensive cradle-to-gate LCA models for HPQ to better understand these trade-offs and ensure alignment with the EU Green Deal and Critical Raw Materials Act goals.

To assess the comparative potential of European HPQ sources, we applied a simple decision matrix approach. Three main criteria were considered: (1) purity (geochemical suitability, Fe/Ti/Al content), (2) tonnage (geological resource size), and (3) processing feasibility (beneficiation test results, infrastructure proximity). Each criterion was scored on a scale of 1 (low) to 5 (high). The results are shown in

Table 3. Scoring matrix for selected European quartz deposits [28,111,113].

Deposit (Country)	Purity (1–5)	Tonnage (1–5)	Processing Feasibility (1–5)	Total (Max 15)	Remarks
Evje–Iveland (Norway)	4	3	5	12	Low impurities; close to drag refining plants) [111].
Panasqueira (Portugal)	3	4	4	11	By-product quartz; beneficiation potential demonstrated [113].
Beauvoir (France)	3	3	3	9	Lithium-bearing granite; moderate impurities [28].
Zinnwald (Germany)	2	3	2	7	Fine-grained greisen quartz; higher impurities [28].
Spain (Galicia pegmatites)	3	2	3	8	Small pegmatite bodies [28].

.

5. Conclusions and Future Perspectives

This review emphasizes new promising deposit types and technological innovations that could transform the sector. These advancements enhance Europe’s resource base and support increased strategic independence. By promoting innovation and utilizing local resources, the EU can lessen reliance on external supply chains and position itself as a leader in sustainable, resilient industrial growth. Although progress has been made in beneficiation and purification, there are still research gaps regarding high-purity quartz (HPQ). Future research should focus on AI-powered sorting and process optimization—using machine learning and sensor-based techniques to improve mining and beneficiation selectivity, reduce waste, and boost feed quality. Incorporating AI into flotation control and reagent dosing could also enhance recovery rates and decrease chemical use.

Plasma and advanced purification technologies—non-traditional methods such as plasma arc treatment, microwave-assisted purification, and novel reagent chemistries promise to achieve ultra-high-purity levels (>6 N) with lower energy consumption than conventional acid leaching and thermal refining.

Circular economy and secondary resources—recycling quartz from tailings, electronic waste, and solar PV end-of-life modules represents an untapped opportunity. Developing flowsheets for reprocessing fine-grained tailings or reclaiming quartz crucibles and glass could reduce dependence on primary mining and align HPQ production with EU sustainability policies.

Thermodynamic and kinetic modelling—more work is needed on detailed thermodynamic modelling of high-temperature and hydrometallurgical pathways, supported by Eh–pH stability analyses, to optimize process parameters and minimize impurity carryover.

Sustainability assessment, such as life cycle assessment (LCA) and carbon footprint modeling for HPQ operations, is currently limited. Implementing these tools could identify key areas of water use, energy consumption, and emissions, helping align policies with the EU Green Deal and Critical Raw Materials Act. Addressing these gaps can encourage future research to develop more efficient, sustainable, and resilient HPQ supply chains, thereby strengthening the mineral’s role in semiconductors, photovoltaics, and advanced glass applications. This review synthesizes mineralogy, geochemistry, and processing technology insights to determine which quartz deposits are best suited for HPQ production. Emphasis is placed on aligning deposit characteristics with Europe’s strategic goals for securing raw materials.