To What Extent Are the Type Localities of Minerals Part of Geological Heritage? A Global Review and the Case of Spain as an Example

Abstract

Currently, approximately 6000 mineral species have been identified, and every year, approximately 100 more are discovered. The discovery of a new mineral has a close relationship with geological heritage. It involves the definition of both the type mineral (the specimen from which the sample used for the description of the new mineral species was obtained) and the type locality (the location where the corresponding specimen was found). All type minerals constitute elements of movable geological heritage and must be kept in a museum or a reference research center. However, not all type localities are recognized as geological heritage sites (geosites), despite their connection to a heritage interest. This article discusses these different considerations regarding type minerals and type localities as geological heritage in a general context. In addition, the situation in the case of Spain is analyzed, which, for various reasons, can serve as a model at the international level. It is concluded that type localities should be considered part of the geological heritage, and that the number of type minerals is always greater than that of type localities.

1. Introduction

“A mineral is an element or a chemical compound that is normally crystalline and that has been formed as a result of geological processes” [1]. It is a natural inorganic substance that has an internal structure and a characteristic chemical composition and form of crystallization, which determines certain physical properties. In mineralogy, the term “mineral species”, which is defined by differences in the chemical composition and crystalline structure of minerals and can be determined via characterization methods, is also commonly used. The number of known mineral species on Earth as of September 2023 [2] is 5975. This number is constantly changing, since approximately 100 new mineral species are discovered each year, and reclassifications are also made that modify the total number.

The place where a specimen that gave rise to the first scientific description of a mineral species was collected is called the “mineral-type locality”, and the specimen constitutes the “type mineral”. The number of type localities is somewhat lower than the number of type minerals since there are some places where more than one mineral species has been described for the first time. The authors of [3] compiled an inventory of type localities in which more than three mineral species had been discovered up to the end of the 1990s, with more than 200 places meeting this condition. It is unknown when the term type locality was first used, since it is not mentioned in the oldest publications, but its use has become common since the second half of the 20th century [4].

Geological heritage is formed by geological formations and/or structures, landforms, minerals, rocks, meteorites, fossils, soils, and any other aspects resulting from geological processes that have scientific and educational value [5]. It is evident that minerals and their deposits are part of geological heritage; they have, therefore, been regularly included in geological heritage inventories [6,7,8,9,10,11]. However, as stated by Ruban [12], paradoxically, the relationship between minerals and (geosites) is not yet well conceptualized and requires more related research, especially with respect to type localities and type minerals.

Meanwhile, localities and reference elements that serve as correlation patterns are widely accepted as part of geological heritage, especially at the international level; these include stratotypes, type series, holotypes, or type localities [7,13], whether of mineralogical, paleontological, stratigraphic, or other interest. Ruban [12] reflects on the role of the “geosites of new mineral discoveries”, that is, of type localities.

According to the above, the definition of a new mineral species is related to the geological heritage, both in relation to the specimen (type mineral) and the outcrop (type locality) (Figure 1). In relation to the type mineral, the International Mineralogical Association (IMA) stipulates that it must be deposited in a museum or reference research center, whose location must be specified [14]. In this way, the specimen forms part of the movable geological heritage, that is, the heritage that is outside the original outcrop, and is part of a public or private collection. In relation to the outcrop, the IMA also records information regarding the location of the deposit in which the type mineral was obtained, at the levels of (1) field/mine/outcrop, (2) locality, and (3) country. In this sense, the type locality represents part of immovable or in situ geological heritage, as Ruban [12] also considers.

However, there are some issues that need to be accounted for when considering mineral-type localities as geological heritage. On the one hand, the type locality of a mineral does not have to be where the most and best samples of a given mineral species are found, but rather where the species was defined for the first time. Therefore, in the consideration of the type localities and type minerals as part of the geological heritage, historical aspects, in addition to scientific aspects (uniqueness, representativeness, etc.), should be taken into account. In addition, the original deposit may be exhausted or have disappeared, or its location may be unknown (in the case of old type localities). New minerals have also been discovered in meteorites (and, therefore, their location is decontextualized from the geological evolution of the area) or even in soundings hundreds of meters deep below the surface or under the sea.

Given the above, several questions arise: Does it make sense to consider thousands of locations as part of the geological heritage simply because new mineral species were discovered there? If the mineral deposit is exhausted, does it make sense to consider an outcrop as part of the geological heritage when the element that makes it unique can no longer be found? Does it make sense to consider as part of the geological heritage an outcrop that was once a reference but currently (in some cases) does not provide particularly unique information because better deposits have been found? What is significant from the perspective of the geological heritage: is it the type locality, the type specimen, or both? These aspects are discussed in this paper. The objectives of this study are (1) to analyze the role of mineral-type localities from the perspective of geological heritage and to debate to what degree they are part of geological heritage; (2) to analyze the relationships between type localities and type minerals and movable geological heritage; and (3) to discuss the management needs regarding the type localities of minerals. For this purpose, the process of declaring a new mineral species is contextualized within the framework of geological heritage and the current situation of the type localities around the world. Special emphasis is placed on the case of Spain, since although this country has a moderate number of mineral-type localities, they have high representativeness and can serve as examples for study and management in other areas. In addition, Spain has a long tradition in the study and conservation of geological heritage, which started in the 1970s and was strongly promoted by legislation that remains very supportive of geoconservation in the 21st century [15]. It can, thus, serve as an example for other countries.

There are few previous studies that delve into this matter, although it is worth noting the contribution of Ruban [12], whose conclusions are analyzed in the context of this research.

2. Materials and Methods

This study of mineralogical type localities was conducted comprehensively, covering all countries where at least 10 type localities have been described. Subsequently, special emphasis was placed on the case of Spain, since, although this country has a moderate number of mineral-type localities, they have high representativeness and can serve as examples for study and management in other areas. In addition, Spain has a long tradition in the study and conservation of geological heritage, which started in the 1970s and was strongly promoted by legislation that remains very supportive of geoconservation in the 21st century [15]. It can, thus, serve as an example for other countries.

The methodology adopted in this study was based on a bibliographic review of the presence of minerals in the world according to the IMA and MINDAT databases, as well as a review of inventories and works on geological heritage, visits to outcrops (Spanish type localities) (Figure 2), visits to collections (of museums and individuals), and the revision and update of information referring to Spanish type localities (many of them erroneous, especially those before 1950). Data on minerals and type localities from the IMA and Mindat databases were accessed in October 2023.

In numerous instances, errors stem from the misattribution of the mineral’s geographic origin. For example, although many minerals are often named after the population from which they come, in Spain, there are several that have been named after other localities or regions by mistake. So, despite their names, neither andalusite was discovered in Andalusia, nor aragonite in Aragón.

3. Results

3.1. Global Situation

The formal and authorized approval of a mineral species is given by the Commission of New Minerals Nomenclature and Classification (CNMNC), which belongs to the IMA and, in turn, is attached to the International Union of Geological Sciences (IUGS). The CNMNC is the competent authority for the definition, approval, nomenclature, and classification of an already known or new mineral. Both the IMA and the CNMNC are composed of professional mineralogists appointed by the mineralogical societies of different countries. The CNMNC periodically publishes the list of accepted minerals on the IMA [2]. This work is based on the September 2023 list, which includes a total of 5975 mineral species.

Before a new mineral can be accepted in the scientific literature, it must be approved by the CNMNC. The process of approval of a new mineral by the CNMNC involves three steps: (1) the discovery and characterization of the new mineral species; (2) the presentation of the new species proposal to the CNMNC; and (3) the approval of the new mineral by the CNMNC. After approval by the CNMNC, the authors of the request have two years to publish the description of the new mineral in a scientific journal. If the description of the new mineral has not been published by the end of this period, the proposal will no longer be considered approved. The description of the new mineral species should include information on its occurrence in relation to its (1) geographical location, (2) geological environment, (3) paragenesis, and (4) list of associated minerals, particularly those in apparent equilibrium with the new mineral [16]. In this way, the type mineral and its name are determined, and information on the type locality or the place where the specimen was found is recorded.

The IMA began to use the concept of type mineral and type locality in 1959, and since then, the CNMNC has been in charge of approving all new minerals. As of that date, it is necessary to keep the specimen that gave rise to the first description of a mineral in a museum or an important collection and to allow access to other researchers, in case of later reconsiderations. Therefore, from the beginning, minerals form part of the movable geological heritage.

Thus, two clearly differentiated stages in the history of mineral types can be considered: the pre-IMA era (until 1959) and the IMA era (from 1959 to the present). Before 1959, the information conserved and known was limited, and the mineral species that already existed in the literature and that were accepted in the scientific field were accepted by the CNMNC without revision or change. These minerals constitute the “grandfathered” category, abbreviated as “G”. During the nineteenth century, approximately 600 mineral species were described, and in the first half of the twentieth century, in the pre-IMA era (until 1959), approximately 570 were identified. The total number of valid mineral species described up to 1959 was 1226.

The vast majority of minerals have been described since 1959, in the IMA era. In just over 60 years, more than 4700 mineral species have been incorporated. The number of new minerals described has increased gradually, exceeding an average of 100 samples per year in the last decade (Figure 3). Specifically, between 2010 and 2020, the number of approved mineral species was 1095, including new discoveries and species that have been renamed or redefined.

The distribution of type minerals worldwide is very uneven. Thus, between the USA and Russia alone, more than 1800 mineral species have been described, representing just over 30% of all those in the world. In addition, there are 15 countries where more than 100 species have been described, the sum of which exceeds 72% of the total (Figure 4).

There are 51 countries that have more than 10 type minerals defined in their territory (

Table 1. Type minerals defined in each country and their relationships with the surface area and the mineral species present in the country, including countries with more than 10 type minerals. TM: type mineral. MS: mineral species existing in each country according to the MINDAT database. RTM: ranking by number of type minerals. RMS: ranking by mineral species. Ratio 1: number of species described in a country for each mineral type. Ratio 2: number of type minerals per 10,000 km². * Antarctica should be considered a specific geographical area, not a nation.

Country	TM	RTM	MS	RMS	Area (S) (km2)	Ratio 1 (MS/TM)	Ratio 2 (MT × 104/S)
USA	908	1	2810	1	9,826,675	3.09	0.92
Russia	894	2	2701	2	17,098,242	3.02	0.52
Italy	397	3	1824	4	301,338	4.59	13.17
Germany	384	4	1916	3	357,121	4.99	10.75
Canada	260	5	1736	5	9,984,670	6.68	0.26
Sweden	194	6	946	18	450,295	4.88	4.31
Australia	189	7	1538	6	7,692,024	8.14	0.25
China	182	8	1478	7	9,596,961	8.12	0.19
Japan	161	9	1412	8	377,944	8.77	4.26
Czech Republic	155	10	1389	9	78,866	8.96	19.65
Chile	147	11	816	25	756,096	5.55	1.94
France	128	12	1357	10	564,690	10.6	2.27
UK	120	13	1079	13	243,610	8.99	4.93
Namibia	109	14	858	23	825,515	7.87	1.32
Dr Congo	103	15	469	37	2,345,410	4.55	0.44
Switzerland	94	16	902	20	41,285	9.6	22.77
Mexico	91	17	806	26	1,972,550	8.86	0.46
Norway	89	18	985	16	385,178	11.07	2.31
Denmark	87	19	573	33	2,210,401	6.59	0.39
South Africa	84	20	965	17	1,221,037	11.49	0.69
Kazakhstan	79	21	744	28	2,724,900	9.42	0.29
Brazil	78	22	942	19	8,515,767	12.08	0.09
Tajikistan	64	23	458	38	143,100	7.16	4.47
Israel	58	24	260	50	20,770	4.48	27.92
Argentina	55	25	861	22	2,780,400	15.65	0.2
Austria	53	26	1183	12	83,855	22.32	6.32
Bolivia	51	27	546	34	1,098,581	10.71	0.46
Greece	47	28	1,000	15	131,957	21.28	3.56
Spain	37	29	1262	11	505,992	34.11	0.73
Finland	36	30	730	29	338,424	20.28	1.06
Romania	35	31	852	24	238,391	24.34	1.47
Poland	32	32	1048	14	312,679	32.75	1.02
Peru	32	33	427	41	1,285,216	13.34	0.25
Morocco	30	34	581	32	446,550	19.37	0.67
Slovakia	28	35	872	21	49,035	31.14	5.71
Kyrgyzstan	25	36	294	48	199,951	11.76	1.25
India	22	37	648	31	3,287,590	29.45	0.07
Madagascar	18	38	389	42	587,041	21.61	0.3
Belgium	18	39	363	44	30,230	20.17	5.95
North Macedonia	18	40	299	47	25,713	16.61	7.00
Antarctica *	17	41	383	43	14,000,000	22.53	0.01
Uzbekistan	17	42	329	45	447,400	19.35	0.38
Portugal	15	43	769	27	92,090	51.27	1.63
Tanzania	15	44	300	46	947,303	20	0.16
Jordan	15	45	194	51	89,342	12.93	1.68
New Zealand	14	46	495	36	268,021	35.36	0.52
Turkey	13	47	431	40	783,562	33.15	0.17
Hungary	12	48	684	30	93,090	57	1.29
Ukraine	12	49	524	35	603,500	43.67	0.20
Iran	12	50	448	39	1,648,195	37.33	0.07
Myanmar	11	51	269	49	676,578	24.45	0.16

). Notably, the two countries that contain the most type minerals are very large (Russia is the largest country in the world, and the USA is the fourth largest behind Russia, Canada, and China). A priori, the larger the surface area is, the more likely it is that mineralogical resources will be found, and the greater the geological diversity. However, as is evident, surface area is only one factor that conditions the geodiversity of a territory. Thus, according to the number of minerals present per 10,000 km² of surface area, the top-ranking countries are small: Israel (with almost 28 type minerals/10,000 km², ranked 149th in the world by national surface area), Switzerland (with 22.77, ranked 132nd), the Czech Republic (with 19.65, ranked 115th), Italy (with 13.17, ranked 71st), and Germany (with 10.75, ranked 62nd), to name only those with more than 10 type minerals per 10,000 km².

The relationships between the surface areas of different countries and the number of type minerals are analyzed to determine a range of species densities [4]. In contrast, to analyze the relationships between type minerals and mineralogical diversity, we introduce an index that relates the mineral species cited in a country (MSs) with the type minerals described in the same place (TMs) according to data obtained from the MINDAT database (Table 1). In general, the countries with the highest numbers of type minerals are those with the lowest ME/TM ratios. According to this index, the countries with low index values are Russia and the USA, in which one out of every three minerals present is a type mineral. Some countries draw attention. For example, in Israel, 1 out of every 4.48 minerals described is a type mineral; the DR Congo presents an MS/TM ratio of 4.59, and Italy is consistently ranked in the top 5 positions according to any index due to its strong tradition in the study of minerals [13].

In general, the data regarding MSs come from the contributions of amateur mineralogists and informative works, in addition to research works, while those of TMs come from scientific works; thus, the lower the MS/TM ratio is, the greater the amount of research devoted to the description of new minerals in that country.

With respect to the relationships between new mineral species and type localities, places where several new mineral species were discovered, that is, type localities of several minerals at the same time, must be considered. An example of such a location is the Khibiny–Lovozero complex on the Kola Peninsula (Russia), which is a type locality for 136 species [3]. The opposite also occurs, although to a much lesser extent; that is, a mineral species may be defined from findings in several places. This is the case for fluorapatite, which shares type localities in deposits in Austria, Germany, Spain, and Switzerland [2]. In addition, 108 mineral species (1.81%) have been defined in meteorites (such as adrianite or bridgmanite), so they are not related to the geology of the area where they were found, and the location of the type locality is not significant. Meanwhile, other mineral species have been defined from small samples collected in wells and boreholes. Examples of this are earlandite, which was defined based on samples included in marine sediments located at a 2580 m depth on the Antarctic continental shelf [17], and ernstburkeite, which was defined from solid inclusions of a few microns in size included in an ice sounding [18]. In 68 cases (1.14%), the origin of a type mineral is unknown; this is especially common among the mineral species defined in the pre-IMA era, which are referred to as “grandfathered” (G). These minerals have been used and known since ancient times and include some native elements (gold, silver, iron, copper, sulfur, and mercury), metallic ores (cinnabar, galena, and pyrite), minerals used for ornamental use (beryl, diamond, malachite, opal, and topaz), and other minerals used daily (borax, chalcanthite, gypsum, nitro, and talc). Thus, having been accepted for their use or traditional knowledge, in many cases, they do not meet the current standards of the IMA, which require the characterization of the mineral and its type locality. In contrast, despite having been discovered a long time ago, some very common minerals exist for which information regarding the year of discovery and/or the country of origin is preserved. These minerals include almandine, andalusite, aragonite, chalcopyrite, corundum, dolomite, staurolite, graphite, and trona.

Mineralogical research is very active. In addition to the discovery of new mineral species, there are continuous reclassifications of samples and even groups that entail changes in nomenclature, and the total number of type minerals, and, therefore, type localities, changes. These changes are due to the following factors [16]: (1) redefinition; (2) discussion, if it can be demonstrated that the mineral is identical to another that has priority or if the name is misleading; and (3) revalidation, if it is observed again in the sample that the mineral meets the normal criteria for crediting that it constitutes a new mineral species or that it is a mixture that contains a new mineral species.

Thus, the status of mineral species according to the IMA can be described as follows: approved (A), which applies to minerals approved after the establishment of the IMA in 1958; grandfathered (G), which applies to minerals discovered before the establishment of the IMA that are generally considered valid species; redefined (Rd), for existing minerals that were redefined during the IMA era; renamed (Rn), for existing minerals that were renamed during the IMA era; and questionable (Q), for poorly characterized minerals, whose validity is doubtful. These are mostly from the pre-IMA era.

As a consequence of these factors, some minerals that once constituted type minerals have changed names or have even been discredited throughout history, and the type locality from which they originated has lost its significance.

With respect to the legal and environmental protection of type localities, although there are several thousand throughout the world, few enjoy a protection regime. Thus, there are not many examples in the world of type localities that have been protected. In this sense, the declaration as an Antarctic Specially Protected Area (ASPA) of the Larsemann Hills in East Antarctica stands out. As part of the recognized value driving the concession of such protection, the area is the type locality of three minerals: boralsilite, hopinite, and tassieite. Another example is the type locality of spriggite, within the Arkaroola Protection Area in South Australia.

Although this example can be considered an exception, the presence of mineralogical type localities is one of the characteristics that the IUCN considers key elements of a geoheritage protected area [19].

In the IUGS Geological Heritage Sites inventory, which began in 2022, some areas were included for being a type locality of several minerals: the Tsumeb ore deposit (Namibia, a type locality of 72 minerals), Broken Hill (Australia, a type locality of 26 minerals), The Kalahari Manganese Field (South Africa, a type locality of 29 minerals), and Mont Sant Hilaire (Canada, a type locality of 73 minerals). While inclusion in the inventory does not entail legal protection, it means international recognition.

3.2. Case of Spain

The relationship between the geological heritage and the type localities of minerals in Spain is interesting because it can provide some insights for consideration on a global scale. The Spanish case presents particularities in relation to (1) the existing mineralogical diversity, (2) the high representativeness shown by its type localities, (3) the long mining/mineralogical tradition, and (4) the existing experience in geoconservation.

Spain has a moderately high number of mineral types. According to the IMA data, 42 species have been defined (Figure 5), which places the country in 29th place in the global ranking by number of type minerals (Table 1). However, despite this position, Spain has great mineralogical diversity, ranking 11th in terms of the presence of mineral species in its territory (Table 1; MINDAT).

Historically, the first minerals defined in Spain date back to the 18th century (

Table 2. Type minerals described in Spain. These minerals, as explained in the text, can be classified into the following types: approved (A), grandfathered (G), redefined (Rd), renamed (Rn), and questionable (Q).

	Mineral	Composition	Type	Year	Type Location (Reference)
1	Aragonite	Ca(CO3)	G	1791	Molina de Aragón, Guadalajara [20]
2	Andalusite	Al2SiO5	G	1798	El Cardoso de la Sierra, Guadalajara [21]
3	Rutile	TiO2	G	1803	Horcajuelo de la Sierra, Madrid [22]
4	Glauberite	Na2Ca(SO4)2	G	1808	Villarrubia de Santiago, Toledo [23]
5	Linarite	CuPb(SO4)(OH)2	G	1822	Linares, Jaén [24]
6	Calomel	HgCl	G	1825	Almadén, Ciudad Real [25]
7	Conichalcite	CaCu(AsO4)(OH)	G	1849	Hinojosa del Duque, Córdoba [26]
8	Morenosite	Ni(SO4)·7H2O	G	1851	Cedeira, A Coruña [27]
9	Zaratite	Ni3(CO3)(OH)4·4H2O	Q	1851	Cedeira, A Coruña [28]
10	Zinkosite	Zn(SO4)	G	1852	Cuevas del Almanzora, Almería [29]
11	Ferberite	Fe2+(WO4)	G	1863	Cuevas del Almanzora, Almería [30]
12	Bolivarite	Al2(PO4)(OH)3·4H2O	Q	1921	Pontevedra [31]
13	Cervantite	Sb3+Sb5+O4	Rd	1962	Cervantes, Lugo [32]
14	Rodalquilarite	H3Fe3+2(Te4+O3)4Cl	A	1967	Nijar, Almeria [33]
15	Yagiite	NaMg2(AlMg2Si12)O30	A	1968	Colomera meteorite [34]
16	Westerveldite	FeAs	A	1971	Ojen, Malaga [35]
17	Jarosite	KFe3+3(SO4)2(OH)6	Rd	1987	Cuevas del Almanzora, Almería [36]
18	Aerinite	(Ca,Na)6(Fe3+,Fe2+,Mg,Al)4(Al,Mg)6Si12O36 (OH)12(CO3)·12H2O	Rd	1988	Estopiñán del Castillo, Huesca [37]
19	Villamaninite	CuS2	Rd	1989	Cármenes, Leon [38]
20	Saliotite	(Li,Na)Al3(Si3Al)O10(OH)5	A	1990	Nijar, Almeria [39]
21	Barquillite	Cu2(Cd,Fe)GeS4	A	1996	Villar de la Yegua, Salamanca [40]
22	Moganite	SiO2·nH2O	Rn	1999	Mogán, Las Palmas [41]
23	Calderonite	Pb2Fe3+(VO4)2(OH)	A	2001	Santa Marta, Badajoz [42]
24	Cobaltarthurite	CoFe3+2(AsO4)2(OH)2·4H2O	A	2001	Mazarrón, Murcia [43]
25	Barahonaite–(Al)	(Ca,Cu,Na,Fe3+,Al)12Al2 (AsO4)8(OH,Cl)x·nH2O	A	2006	Mazarrón, Murcia [44]
26	Barahonaite–(Fe)	(Ca,Cu,Na,Fe3+,Al)12 Fe3+2(AsO4)8(OH,Cl)x·nH2O	A	2006	Mazarrón, Murcia [44]
27	Suhailite	(NH4)Fe2+3(Si3Al)O10(OH)2	A	2007	Mijas, Malaga [45]
28	Natropharmacoalumite	NaAl4(AsO4)3(OH)4·4H2O	A	2010	Nijar, Almeria [46]
29	Chlorapatite	Ca5(PO4)3Cl	Rn	2010	Cabo de Gata, Almeria [47]
30	Fluorapatite	Ca5(PO4)3F	Rn	2010	Cabo de Gata, Almeria [47]
31	Hydroniumpharmaco-alumite	(H3O)Al4(AsO4)3(OH)4 ∙4.5H2O	A	2012	Nijar, Almeria [48]
32	Ferri-pedrizite	NaLi2(Mg2Fe3+2Li)Si8O22(OH)2	Rd	2012	Manzanares el Real, Madrid [49]
33	Clino-ferro-ferri-holmquistite	Li2(Fe2+3Fe3+2)Si8O22(OH)2	Rd	2012	Manzanares el Real, Madrid [50]
34	Ferro-ferri-pedrizite	NaLi2(Fe2+2Fe3+2Li)Si8O22(OH)2	Rd	2012	Manzanares el Real, Madrid [50]
35	Potassic-ferro-taramite	K(NaCa)(Fe2+3Al2)(Si6Al2)O22 (OH)2	Rd	2012	Bédar, Almeria [51]
36	Abellaite	NaPb2(CO3)2(OH)	A	2014	Torre de Cabdella, Lleida [52]
37	Clino-ferri-holmquistite	Li2(Mg3Fe3+2)Si8O22(OH)2	A	2014	Manzanares el Real, Madrid [53]
38	Thenardite	Na2(SO4)	Rn	2014	Ciempozuelos, Madrid [54]
39	Fehrite	MgCu4(SO4)2(OH)6∙6H2O	A	2018	Pechina, Almeria [55]
40	Alcantarillaite	[Fe3+0.5(H2O)4][CaAs3+2(Fe3+2.5W6+0.5)(AsO4)2O7]	A	2019	Balalcázar, Cordoba [56]
41	Ermeloite	Al(PO4)·H2O	A	2021	Moaña, Pontevedra [57]
42	Colomeraite	NaTi3+Si2O6	A	2021	Colomera meteorite [58]

), so there is a long tradition regarding the study of minerals. However, for approximately a century beginning in 1860, only two minerals were discovered, while in the 25 years before 2020, half of the new minerals with type localities described in Spain were discovered (Figure 6).

With respect to the relationships between the 42 new minerals described from Spanish samples and their type localities, there are certain peculiarities. On the one hand, there are several places that are type localities of various mineral species. Thus, the following species were discovered in the same localities: (1) two mineral species, namely, jarosite and zinkosite; chlorapatite and fluorapatite; morenosite and zaratite; and natropharmacoalumite and hydroniumpharmacoalumite; (2) three mineral species, namely, cobaltarthurite, barahonaite–(Al), and barahonaite–(Fe); and (3) four mineral species, namely, clino-ferri-holmquistite, clino-ferro-ferri-holmquistite, ferri-pedrizite, and ferro-ferri-pedrizite. In addition, two new mineral species were defined from samples that came from meteorites (yagiite and colomeraite) and are, therefore, unrelated to the geological environment in which they were found. In addition, for seven other minerals, the locations where the type minerals were first found are not precisely known; this is the case for andalusite, cervantite, chlorapatite, conichalcite, fluorapatite, linarite, and rutile. Finally, the type locality of morenosite and zaratite has been hidden under a landslide in a littoral area and is practically inaccessible. Thus, the total number of known and existing mineral-type localities in Spain is 24.

Minerals are often named after the population from which they come. However, as a curiosity, in Spain, two specimens of new minerals were misplaced when they were being studied and were named after other Spanish populations or regions. Thus, andalusite was discovered in Guadalajara (Castilla La Mancha), not in Andalusia, and aragonite was discovered in Molina de Aragón, also located in the province of Guadalajara (Castilla La Mancha), and, thus, not in Aragon.

With respect to the distribution of the type localities in relation to the geological units (Figure 7), there is a high concentration in the southeastern Iberian Peninsula, where mining operations have abounded given the knowledge of these minerals since ancient times, and where complex tectonics have resulted in numerous mineralizations. However, a singular fact is that the minerals discovered in Spain come from both orogenic variscal fields (units 1, 6, 8, and 11 in Figure 7) and alpine fields (units 7, 9, and 10 in Figure 7), as well as nonorogenic fields (units 12 and 13 in Figure 7).

On the other hand, Spain has long experienced the study and conservation of geological heritage, dating back to the 1970s [8]. Geosites of mineralogical interest can be found in the inventories carried out in those early years. Thus, the Spanish Inventory of Places of Geological Interest (IELIG) establishes assessment criteria that include the possibility of being a type locality of a mineral species for inclusion [59]. This inventory, which has more than 3000 records [60] and is not yet finished, includes the type localities of cervantite (AL094), thenardite (TM038—Salinas de Espartinas), glauberite (TM086—sodium sulfate mineralization of El Castellar, Villarrubia de Santiago), andalusite (CI148—andalusite mineralizations associated with the Detachment of El Cervunal, in El Cardoso), morenosite and zaratite (GM005—Vixía Herbeira-Sierra da Capelada coastal cliffs and Manolita mine deposit), and aragonite (IB118—Río Gallo aragonite deposit). This inventory attributes a higher score to a geosite that is considered a “type or reference locality” of a mineral.

In addition to the national inventory, the IELIG, there are other regional inventories of places of geological interest. Thus, the Andalusian inventory also considers the possibility that an area constitutes a type locality. To assess the scientific interest of a place, 4 possibilities are considered: representativeness (max. 40 points), type locality (30 points), bibliometric index (20 points), and observation conditions (10 points) [61]. The LIG inventory of Aragon includes the type locality of aerinite (“Diapiro, ofitas and aerinite deposit of Estopiñán”), but curiously, it does not refer to the location as a type locality. Meanwhile, Spain also has an excellent legal framework in place to protect its geological heritage [15]. Twenty-seven percent of the national territory is protected under some regional, national, or international environmental category [62]. Many mineralizations of interest are included in Spanish protected areas, but they are rarely the main reason for the declaration. Some examples are the Natural Monuments of the Montera de Gossam (Huelva, SW Spain), the Place of Scientific Interest of the Sierra del Cordel and Minas de Burguillos del Cerro (Badajoz), and the Natural Monument of the Jayona Mine (Badajoz), to mention just three examples. This also occurs with type localities. Therefore, the deposits of 24 type minerals are included in protected areas:

-

Andalusite: although the location of the type locality is not exactly known, it is known to be in El Cardoso de la Sierra (Guadalajara), within the Sierra Norte de Guadalajara Natural Park.

-

Aragonite: in the UNESCO World Geopark of Molina–Alto Tajo (Figure 8).

-

Cervantite: although the exact location of the mine where the specimens that led to its discovery were extracted is unknown, the municipality is included in the UNESCO Biosphere Reserve of Los Ancares Lucenses and Montes de Cervantes, Navia, and Becerreá.

-

Clino-ferri-holmquistite, clino-ferro-ferri-holmquistite, ferri-pedrizite, and ferro-ferri-pedrizite: in Guadarrama National Park.

-

Calomel: in Almadén Mining Park, inscribed on the UNESCO World Heritage list under the name of Mercury Heritage: Almadén and Idrija.

-

Chlorapatite, fluorapatite, hydroniumpharmacoalumite, natropharmacoalumite, and rodalquilarite: in the Natural Park, Biosphere Reserve, and UNESCO World Geopark of Cabo de Gata.

-

Fehrite: in the Natural Park of Sierra Alhamilla.

-

Ferberite, jarosite, and zincosite: in the Spatial Conservation Zone (Natura 2000 Network) of Sierras Almagrera, de los Pinos, and el Aguilón.

-

Moganite: in the Gran Canaria Biosphere Reserve.

-

Morenosite and zaratite: although the place was buried under a coastal landslide, it is included in the UNESCO World Geopark of Cabo Ortegal.

-

Rutile: although the exact location of the type locality is unknown, it is known to be within the Sierra del Rincón Biosphere Reserve.

-

Thenardite: in the Well of Cultural Interest (category of protection of the Cultural Heritage) of the Salinas de Espartinas.

-

Villamaninite: in the Los Argüellos Biosphere Reserve.

-

Westerveldite: in the Sierra de las Nieves Biosphere Reserve and its surroundings.

However, with the exception of aragonite, none of these mineral localities are marked, nor do they have any infrastructure for dissemination or protection.

Figure 8. Poster located in the type locality of aragonite, in the town of Molina de Aragón, in the UNESCO World Geopark of Molina–Alto Tajo.

Figure 8. Poster located in the type locality of aragonite, in the town of Molina de Aragón, in the UNESCO World Geopark of Molina–Alto Tajo.

4. Discussion

4.1. Global Situation

Given the state of mineralogical research, more than one hundred new mineral species are discovered each year. Most of these are increasingly rare mineral species that are relatively small in size and are distinguishable only by complex mineralogical techniques. This is due to two factors: (1) most of the common minerals have already been described, and (2) with the development of modern analytical techniques, it is possible to characterize crystalline structures of nanometric sizes, which allows the description of very small species.

There are fewer type localities than defined mineral species since, at a minimum, there are almost 200 sites that are type localities of more than three mineral species (Evseev, 2003) [3]. This is due, in part, to the fact that there are deposits with rare paragenesis, where several new minerals have been described, and because there are exploitations where minerals have been obtained for decades or even centuries, which increases the possibility of several species appearing in the same place.

The analysis of the mineral species defined in the different countries reflects that geological diversity has an influence, but above all, the wealth and investment in mineral resources are not necessarily made by the country of origin but by the mining companies that operate in that country (national or otherwise). Figure 9 shows that some countries, despite having a moderate diversity of mineral species (RMS), have a high number of type minerals (RTM), such as the DR Congo (15), and fall above the line in the graph. Moreover, other countries with high geodiversity, such as Spain (29) or Poland (32), which are below the line, have few type minerals.

With respect to the relationship between new minerals and geological heritage, all definitions of geological heritage include minerals as prominent elements. In the same way, type localities are also considered part of the geological heritage, be they paleontological, stratigraphic, mineralogical, petrological, etc. Therefore, the discovery of a new mineral species is related to the geological heritage in relation to (1) the original specimen or type mineral and (2) the place where it was found, that is, the type locality. In fact, the IMA declares the type mineral, not the type locality, although it requires information about the latter. Therefore, the discovery of a new mineral is important both from the point of view of the movable geological heritage (type mineral) and from the perspective of the immovable geological heritage (type locality), and the two aspects are inseparable.

The mineral-type localities are clearly part of the geological heritage. Jiménez Martínez [11] noted that being a type locality is a sufficient condition for a place to be selected for evaluation in the Spanish Inventory of Places of Geological Interest (IELIG). Ruban [18] specified that new mineral localities (NMD localities) should be considered geosites for two main reasons: (1) such localities have played an outstanding role in the development of geosciences, and finding new minerals in nature extends our understanding of the Earth’s diversity and complexity, and (2) such localities provide unique opportunities for further research, and new mineral discovery localities are the main target objects for in-depth research linked to such rare minerals.

In accordance with these ideas, in a general way, a series of aspects related to the relationship between mineral-type localities and geological heritage must be clarified:

(1)

Not all the new mineral species define a type locality, since the origin of the sample that gave rise to the first determination may be unknown. Thus, there is a unique equivalence between mineral species and type minerals but not between mineral species and the type locality, such that not all mineral species have a type locality that can be a geosite; instead, there are several possible cases.

(2)

Type localities do not always offer the opportunity for new studies, as stated by Ruban (2018). This is particularly the case for those discovered in recent decades because material for determinations has been obtained and exhausted. In other words, there may be no more minerals remaining in the type locality; therefore, no further studies can be carried out.

(3)

Sometimes, the specimen from which the new mineral species was extracted is not related to the geological environment, as with the type minerals described from meteorites, such that the place where it was found is completely decontextualized and not geological or paragenetic. In this case, the concept of type locality is meaningless from the heritage point of view, and no geosite is defined.

(4)

Advances in mineralogy have led to reclassifications that modify the status of mineral species. In such cases, the type locality of a certain mineral species may lose its significance when the species is reclassified and loses its status as a new species. Such problems can occur at any type of locality, and as stated by Ruban [12], if a mineral species was described from a specimen, it means that at the time, it was a milestone in geological knowledge and was assigned special value. Brocx and Semeniuk [7] also insist on the idea of the patrimonial value of “historically significant sites where original contributions to the understanding of geological processes or principles were inspired” and argue that such sites should be part of geological heritage, regardless of whether their status is later revoked by advances.

(5)

Some minerals have been discovered in deep boreholes and inaccessible areas, so they do not define a geosite.

(6)

Are there some type localities that are dumps? A dump is an anthropically modified place, so it should not constitute a geosite or a type locality. However, in some cases, the deposit is completely depleted, and the only place where the type specimens can be observed is in the dumps of mining operations; thus, in this case, these places show paragenesis of the type locality and can be used as reserves of type samples.

(7)

An important aspect is to evaluate the degree of relevance of the type localities. Not all the elements of geological heritage have the same degree of interest, and they are frequently categorized as local, regional, national, or international [7]. Ruban [12] proposed that, at a minimum, type localities should have national relevance since they represent the place where a new mineral was discovered for the scientific community worldwide. The problem with assigning them international relevance is that the concept of world geological heritage makes sense when the elements that compose it are exclusive and relatively limited in number. Type localities can be considered exclusive, but in number, they would amount to several thousand geosites of international relevance. If thousands of other geosites from different earth science disciplines were added, the concept of geological heritage of global relevance would be distorted by the excessive number of sites. Therefore, it seems appropriate that the type localities are included in national inventories and that this characteristic is valuable, although not definitive, when proposing geosites of international relevance.

(8)

Is it necessary to consider the type locality as part of the geological heritage, or is it preferable to look for the best deposit of the mineral in question? The declaration of the type mineral includes scientific, historical, and geographical aspects inherent to the type locality; therefore, it is this aspect that must be considered in heritage inventories.

(9)

Does it make sense to consider as heritage an exhausted type locality, or a type locality where it is no longer possible to find specimens of the mineral that gave rise to its classification as such? Regardless of the existence of these minerals, the type locality includes the elements of scientific interest that motivated the declaration, such as the genetic environment and the paragenesis present in the description of the mineral, in addition to the historical and geographical aspects collected in the declaration; therefore, the inclusion of the locality in the national inventories of geosites is recommended.

Regarding the possible parallelism between the type localities of minerals and the stratotypes of world relevance, the discovery of a new mineral in a place represents a milestone in the knowledge of geology, as mentioned by Ruban [12], but this does not mean that it is the best or most complete outcrop. Instead, its importance is due to the fact that, at a certain moment, the first described specimens were extracted from that location. Here, the mineral-type localities and the stratigraphic-type localities differ greatly. The latter, called the Global Standard Stratotype Section and Point (GSSP) when they are global in scale and are defined by the International Commission on Stratigraphy (ICS) of the International Union of Geological Sciences (IUGS), indicates the best world section for a certain time period [63], regardless of whether it was discovered first or not. In other words, the fundamental criterion is quality. However, for the type localities of minerals, the first appearance is considered; therefore, historical and nonscientific criteria are taken into account. Meanwhile, it is also necessary to consider the different numbers of mineral-type locations (approximately 6000) and GSSPs (approximately 130), which indicate different degrees of exclusivity. Another important difference between the GSSP and the mineral-type localities is that in the former, the place is essential and is what the ICS declares, while in the discovery of a mineral species, the essential aspect is the type mineral and the IMA declaration of a new mineral species. In the latter case, the place of discovery is an important fact but is only associated with the specimen. Finally, and derived from the above, the ICS requires the legal protection of the GSSP and ensures its conservation so that it maintains its status, but the IMA does not require the protection of the mineral-type locality.

The protection of type localities should be a priority since they are prominent geosites and can suffer pillage or destruction by exploitation of the outcrop. Many type minerals have been discovered in active mining operations, so their protection can be complex and even problematic. However, in a vast majority of cases, these are places where mining, if any, has ended. Therefore, in geosites susceptible to looting, assigning a protection regime is important. In certain cases, it could be appropriate to install educational and/or tourist resources.

4.2. Case of Spain

The Spanish case has characteristics that may offer lessons applicable on an international scale. One particularity is that it has fewer type localities than would be expected on the basis of the number of mineral species cited in Spain. In fact, as shown in Figure 9, Spain is one of the countries with the worst relationship between mineralogical diversity and type minerals identified in its territory. Among the 51 countries with more than 10 type minerals (represented in Table 1 and Figure 9), Spain has the worst relationship. Portugal, a country with many geological, geographical, and cultural similarities, presents a similar situation. This is striking because the first minerals discovered in Spain date back to the 18th century, and although few new minerals have been discovered, some of them are very common, such as aragonite, andalusite, or rutile. Slightly more than 1/3 of the minerals found in Spain have been identified in the last 20 years. This reflects a certain parallelism with the world trend, given that 43.9% of the known mineral species have been discovered in the last two decades. This is due to both the improvement in analytical techniques and the development of mineral collecting, which allows many amateurs to show great dedication to the search for specimens and promote the description of new species. The fact that few new minerals have been discovered is due to three factors: a low economic investment in this matter, the absence of working groups dedicated specifically to the discovery of minerals and the lack of interest on the part of researchers owing to the cost of the research, considering the difficulty of describing a new species and, therefore, of generating impact publications.

The type localities in Spain are widely representative in terms of the potential scenarios regarding such localities. Thus, of the forty-two new mineral species defined in Spain,

-

Fifteen species were collected from localities with several type minerals per locality.

-

In seven cases, the place of origin of the type mineral is unknown; therefore, only approximate information is available on the type locality.

-

Two minerals come from meteorites and, therefore, cannot generate geosites.

-

The type locality of two mineral species is inaccessible because it is hidden by a landslide.

-

Two type localities (potassic-ferro-taramite and ermeloite) do not contain more mineralization because they have been depleted.

-

Twenty-four types of minerals are located within a protected natural space.

-

Only one type locality is marked (Figure 8).

This means that of the 42 type minerals, 24 could be defined as geosites, understood as specific, known, delimitable, and physically accessible places (

Table 3. Minerals discovered in Spain and their characteristics. Generated geosite: its type locality corresponds to a specific, known, delimitable, and physically accessible place. Threatened conservation: there are real threats of degradation due to industrial exploitation or looting. In protected areas, the type locality is included within the perimeter of a protected area or similar area and its category. Educational and/or tourist potential: due to the characteristics of the place, it is possible to design educational activities in the locality or carry out geotourism initiatives, although they are currently not carried out or may not be carried out in the specific place of the type locality. The numbering corresponds to that of Figure 5 and Figure 7.

	Mineral	Generated Geosite	Threatened Conservation	In Protected Space	Educational and/or Tourist Potential
1	Aragonite	1	No	World Geopark of UNESCO	Yes; signposted
2	Andalusite	No	No	Natural Park	Yes
3	Rutile	No	No	Biosphere Reserve	Yes
4	Glauberite	2	No	No	Yes
5	Linarite	No	-	No	-
6	Calomel	3	No	UNESCO World Heritage	Yes
7	Conichalcite	No	-	No	No
8	Morenosite	No	Yes	World Geopark of UNESCO	-
9	Zaratite	No	Yes	World Geopark of UNESCO	-
10	Zinkosite	4	Yes	Natural area	Yes
11	Ferberite	5	-	Spatial Conservation Zone (Red Natura 2000)	Yes
12	Bolivarite	6	Yes	No	-
13	Cervantite	No	-	Special Protection Area for Natural Values	-
14	Rodalquilarite	7	No	UNESCO Global Geopark Natural Park Biosphere Reserve	Yes
15	Yagiite	No	-	-	-
16	Westerveldite	8	Yes	Biosphere Reserve	Yes
17	Jarosite	4	Yes	Natural area	Yes
18	Aerinite	9	No	No	Yes
19	Villamaninite	10	No	Biosphere Reserve	Yes
20	Saliotite	11	No	No	Yes
21	Barquillite	12	-	No	No
22	Moganite	13	No	Biosphere Reserve	Yes
23	Calderonite	14	No	No	Yes
24	Cobaltarthurite	15	No	No	Yes
25	Barahonaite- (Al)	15	No	No	Yes
26	Barahonaite- (Fe)	15	No	No	Yes
27	Suhailite	16	Yes	No	Yes
28	Natropharmacoalumite	17	No	Idem 14	Yes
29	Chlorapatite	No	-	Idem 14	-
30	Fluorapatite	No	-	Idem 14	-
31	Hydroniumpharmacoalumite	17	No	Idem 14	Yes
32	Ferri-pedrizite	18	No	National Park	Yes
33	Clino-ferro-ferri-holmquistite	18	No	National Park	Yes
34	Ferro-ferri-pedrizite	18	No	National Park	Yes
35	Potassic-ferro-taramite	19	-	No	-
36	Abellaite	20	-	No	Yes
37	Clino-ferri-holmquistite	18	No	National Park	Yes
38	Thenardite	21	No	BIC	Yes
39	Fehrite	22	-	Natural Park	-
40	Alcantarillaite	23	Yes	No	-
41	Ermeloite	24	Yes	No	-
42	Colomeraite	No	-	-	-

). This confirms, with a real case, the non-equivalence between type locality and geosite establishment. To date, only one of these geosites is marked, and none of them has educational or tourist infrastructure. Although 24 type minerals have their locality included in the perimeter of some type of protected space (national parks, nature reserves, etc.), their existence was not considered in the process of declaring the protected area. Moreover, in none of the cases does this characteristic appear as a value to be highlighted in the declaration document of the protected space in which they are included. This reflects that, despite their didactic potential and importance for the advancement of science, mineral-type localities do not receive much consideration in Spain, despite its advancements in terms of geoconservation and its long tradition in the study of mineralogy.

In relation to the equivalence with the GSSP, in Spain, seven GSSPs have been identified. Among them, four are legally protected under environmental protection, and the other three are not threatened. Meanwhile, five of them are signposted and equipped with information panels, while two have been recently declared. For the latter two, informational infrastructure has not yet been installed, but it is reasonable to expect that it will be. However, while it is required that GSSPs preserve their status, this is not the case for mineral-type locations.

Although type localities are present in inventories of geological heritage carried out in Spain, not all of them are included in the Spanish Inventory of Places of Geological Interest.

In terms of protection and educational and tourist use, of the 24 possible geosites that define the mineral species discovered in Spain, 8 are threatened by looting or destruction. This means that there is a possibility that they will disappear in the short term. Meanwhile, 20 are of interest from the educational or touristic point of view (Table 3). Some of these are in places that are difficult to access or in places where tourism would represent a risk because they are the sites of old mining operations, whose adaptation for visitors would be complex and expensive. Overall, it would make sense to condition or protect only 15 of the 24 potential mineral-type localities defined in Spain. This confirms the general idea that there is no direct equivalence between type localities, geosites, and protected spaces. In addition, it must be considered that some type localities are highly depleted or very small; thus, inviting visitors could entail the danger of looting. Therefore, the potential for public and tourist uses must be studied in each case.

Perhaps the three most significant cases are as follows:

-

Guadarrama National Park, where four new mineral species have been defined, has the highest degree of environmental protection assigned by Spanish legislation, with three million visitors a year and five visitor and interpretation centers, one of which is in the sector where new minerals were discovered (La Pedriza).

-

UNESCO World Geopark of Molina–Alto Tajo, where the aragonite type locality is located, is marked with a sign, and the geopark museum has a space dedicated exclusively to this mineral.

-

The Cabo de Gata UNESCO World Geopark, which is simultaneously a UNESCO Biosphere Reserve and a Natural Park, is a site where five mineral species have been discovered, although the exact locations of two of them are unknown. The geopark has an interpretation center in the area with the greatest mining wealth (Rodalquilar).

5. Conclusions

Each year, more than 100 new mineral species are discovered. To be assigned the status of a new mineral, the IMA requires that some type specimen be deposited as permanent reference material in at least one important museum or nationally recognized mineral collection [16], recognizing an example of movable geological heritage. Moreover, the discovery of a new mineral defines a type locality that does not always generate a geosite. Thus, there is no direct relationship between the type localities of minerals and geosites, and not all mineral species are associated with a type locality that can be considered a geosite. The lack of information on the precise location, geological decontextualization of the environment, degradation of the place, or inaccessibility causes some localities to have no meaning from the perspective of geological heritage. It is also necessary to consider the null patrimonial importance that is given to type localities in the international arena.

In general terms, in countries where there is a greater number of minerals, there are also a greater number of type localities and, therefore, more type minerals. However, other countries with high mineralogical diversity have few new mineral species discovered. This is mainly because the discovery of new mineral species is currently directly associated with investment in research, either by the authorities of the country of origin or by the authorities of other countries that extract specimens and analyze them in the territory where they are discovered.

Spain is a country that is representative of the current situation of the relationship between the discovery of new mineral species and geological heritage. In Spain, 42 new mineral species have been defined, but only 24 geosites could be established. For a type locality to be considered a geosite, its location must be precisely known, it must be physically accessible, and it must be possible to delimit it cartographically. Depending on the actions for public use that may be carried out, the geosite may be of eminently scientific interest or have potential for tourism and educational use. However, very few standard locations around the world are used for these purposes. Thus, the didactic and tourism use of the type localities of minerals is a pending issue on a global scale. With respect to their protection, almost no localities are protected on the sole basis of this characteristic, although some are included within the perimeter of a protected space. The Spanish case offers a good example, as despite its great experience in geoconservation and the existence of favorable legislation for geoconservation, the type localities of minerals are not considered valuable.

Some specimens constituted type minerals for a time, but subsequent analyses revealed that they were erroneously classified; this can lead to name changes and or discreditation. In any case, at the time, they represented an important advancement for science. This reflects that, in many cases, the type localities respond more to cultural or historical factors than to their strictly geological value, since they mark the first discovery, not the best outcrop.

Type localities should be included in the national inventories of geosites in the same way that type minerals are part of movable geological heritage. In any case, it is very difficult to find information on the degree of protection of the type localities in the different countries. We hope that this article will help to disseminate it more widely.