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Article

Characterization of the Stone Masonries and Evaluation of the Environmental Impact in Panamá Viejo: A Contribution for the Conservation of the Monumental Complex

by
Chiara Ciantelli
1,*,
Silvia I. Arroyo Duarte
2,3,
Carmela Vaccaro
4 and
Alessandra Bonazza
5
1
ENEA Brasimone Research Centre, Camugnano, 40032 Bologna, Italy
2
Art Department, Facultad de Arquitectura, Universidad de Panamá, (Campus Universitario Octavio Méndez Pereira), Ciudad Universitaria Estafeta Universitaria, Apartado 3366, Panama
3
Sistema Nacional de Investigación (SNI), Panama 01001, Panama
4
Department of Environmental and Prevention Science, University of Ferrara, C.So Ercole I d’Este 32, 44121 Ferrara, Italy
5
Institute of Atmospheric Sciences and Climate, National Research Council of Italy, Via Gobetti 101, 40129 Bologna, Italy
*
Author to whom correspondence should be addressed.
Heritage 2023, 6(10), 6526-6546; https://doi.org/10.3390/heritage6100341
Submission received: 26 July 2023 / Revised: 2 September 2023 / Accepted: 12 September 2023 / Published: 25 September 2023
(This article belongs to the Special Issue Challenges in Stone Heritage Conservation)
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Abstract

:
A fundamental step in the best preservation of heritage materials is investigating their chemical and physical characteristics, and understanding how they interact with the surrounding environment. For this reason, the stone masonry of the monumental UNESCO site of Panamá Viejo was subjected to a thorough study to characterize the materials and evaluate their state of conservation. Additionally, potential outcrops were explored in order to identify sites for the supply of raw materials. The methodological approach encompassed mineralogical-petrographic investigations using stereomicroscopy, polarized light microscopy (PLM), X-ray powder diffraction (XRPD), scanning electron microscopy and energy dispersive X-ray spectrometry (ESEM-EDS) and X-ray fluorescence (XRF). The results revealed that the masonries primarily consists of polygenic breccia, basaltic andesite, rhyodacite, tuffite, and rhyolite. In addition, at the potential quarries, breccia and basaltic andesite were identified. The porous structure was studied using mercury intrusion porosimetry (MIP). Possible issues due to salt dissolution/crystallization cycles were considered. Consequently, ion chromatography (IC) was conducted on samples exhibiting alteration patinas to study the presence of soluble salts. In assessing the state of conservation, prevalent forms of deterioration included biological colonization, detachments, material loss, potential salt weathering, and chromatic alteration. In conclusion, the outcomes of this work provide a valuable resource for the current and future preservation of this site.

1. Introduction

Nowadays, the Republic of Panama is mostly known for its renowned Canal, an immense engineering work of significant global trade importance. Situated in the narrowest part of the isthmus of the American continent, Panama has held its role as a strategic crossroad for commercial routes since the 16th century. During this period, it has served as a crucial link between the “New World” and the “Old World”.
It hosted the first Spanish settlement on the Pacific Coast, presently referred to as the “Monumental Complex of Panamá Viejo”, which is nationally used by law, while internationally, it is known as the “Archaeological Site of Panamá Viejo”. Founded more than 500 years ago, precisely on the 15th of August 1519, and due to its exceptional significance, the site was included as an extension of the Historic District of Panama on the World Heritage List in 2003 [1,2].
A few years before, a private, autonomous, non-profit organization of public interest was established: the Patronato of Panamá Viejo. Its mission aims at managing, preserving, and promoting the site [3]. In the pursuit of supporting the conservation and valorization of this unique heritage site, a collaboration started in 2014 among the Patronato, the Institute of Atmospheric Sciences and Climate of the Italian National Research Council (ISAC-CNR), and the Department of Earth Sciences of the University of Ferrara. The central focus of this work was investigating the effects of climate and pollution on the construction materials [4].
In 2014, a sampling campaign was performed to gather representative specimens of the stone masonry buildings and identify potential quarries for the supply of raw materials. Additional information regarding the sampling approach and the analytical techniques are reported in the “Section 2. Materials and Methods” paragraph. Therefore, this study represents an innovative field of research in this region. It offers an exploration on the lithologies utilized as construction materials at the Panamá Viejo site. Moreover, it assesses their state of preservation, considering the interaction between the materials and the environment.

1.1. Historical Background and Site Location

The Monumental Complex of Panamá Viejo, which was originally 60 hectares in size, now encompasses 28 hectares, i.e., when considering the protected area. It extends along the Pacific Coast, situated between the río Algarrobo on the west side and the río Abajo (originally known as the río Gallinero) on the east side, as depicted in Figure 1.
Before becoming the first European outpost on the American Pacific, this area hosted a fishing village belonging to the indigenous Cueva population, with its settlement dating back to approximately 500 AD.
Following the foundation of Panamá Viejo in the 16th century by Pedrarias Dávila, the significance of this site grew over the course of a century and a half. The town was structured with a main square, called Plaza Mayor, located near the sea. The urban layout was characterized by an almost rectilinear grid, an example of early European colonial urbanism [5,6,7].
During the 17th century, the site faced two traumatic events: in 1621, the town was struck by an earthquake and, in 1671, a devasting fire broke out at the site. Subsequent to the latter catastrophe, the settlement was relocated to the current Historic District of Panama, also known as Casco Antiguo. This is situated close to the Ancón Hill, with a superior and more strategic position. The original town was destructed and abandoned, with many of its remains used as a quarry for constructing the “new” Casco Antiguo [5,8,9,10,11].
Today, the site hosts the remnants of buildings constructed during the period between the late 16th century and the 17th century. The majority of these are stone masonry structures belonging to monastic complexes, public and private constructions, each serving particular and/or strategic functions. The custom of exclusively using natural stone for government buildings, churches, convents, and the finest houses began in the late 16th century. However, according to the literature, there were three distinct construction styles: entirely wooden structures, entirely stonework buildings, and a mixed type featuring stone on the lower floor and wood on the upper floor [12]. Only the stonework type has survived to the present day, which was constructed with rocks and mortars. Consequently, the focus of this study is on the stone of this typology of masonry, while the mortar elements were investigated in a previous work [13].
Finally, it is important to mention that it is highly likely that the stone used in the construction was sourced directly from the surrounding area, considering the proximity of quarries [14]. This is documented in a letter dated 1608, from Bartolomé Morquecho to the King, stating: “there is stone in the suburbs of this city, it is very good and at little cost” [15]. The transport of stone from Panama to Peru during the 17th century has also been examined, revealing the abundant availability of the material [12]. For this reason, three outcrops, i.e., potential quarries for the materials used in the stone masonry, were identified and studied.

1.2. Environmental Context

Considering the environmental setting, the site is situated directly facing the ocean, which has led to progressive coastal erosion over the past five centuries [16,17,18]. Presently, the ruins of Panamá Viejo stand approximately 100 m away from the sea [19]. The nearest complex to the shoreline on the western side, Casas Reales, has experienced erosion from tides (Figure 2). In 2008, the consolidation of Casas Reales was performed using traditional materials and construction methods. The walls facing the sea were consolidated and a buttress was built to replace and counter the material loss, preventing the collapse of the wall. Reintegration, waterproofing, and injections were also executed. Additionally, the area surrounding the monument’s ruins was backfilled with soil to mitigate the impact of the sea [20]. It should be noted that the Pacific coast experiences a daily average tidal range of 1.5 m, which occurs twice daily and exhibits periodic peak values of 6.7 m [17].
According to the “thermal zones of the Earth”, a climate classification developed by Köppen–Geiger and validated for the latter half of the 20th century by Kottek et al. [21], the Panamanian region falls under the A category, indicating an equatorial climate zone characterized by two distinct seasons: the dry and rainy season. The latter is the longer of the two, approximately covering the period from April until November/December. For that reason, annual precipitation amount is notably high, with values reaching 2300 mm along the Pacific littoral. Regarding temperature, minimal fluctuations occur throughout the year, maintaining an annual mean of 27 °C. The monthly average relative humidity, recorded at Tocumen (near Panama City), from 1979 to 2008, was approximately between 70% and 85% [22]. Given these thermo-hygrometric conditions, stone masonry can potentially undergo salt weathering, which could lead to disintegration and detachments due to internal material stresses [23].
Furthermore, in Panama, rainfall tends to be intense and of a short duration. This, coupled with the growth of urbanization, has caused the increase in surface runoff. Such runoff has the potential to carry dissolved contaminants, including salts and pollutants, representing a possible further source of danger for the materials [24]. In addition, the high intensity of rainfall can trigger related effects on exposed monuments, such as heightening mechanical erosion and chemical deterioration, due to water permeating the structures [25]. Moreover, the changing of climate can trigger deterioration phenomena in a different way in comparison with nowadays. Phenomena closely linked to precipitation amounts have been previously examined, revealing that the Panamá Viejo area could experience an increment of surface recession on carbonate rocks and the biomass accumulation on hard acid stones could be fostered in the near and distant future [22].
Lastly, the anthropic context should be considered. Panamá Viejo is totally embedded in the urban context of Panama City. Between 1950 and 2013, the monumental site was crossed by one of the city’s major traffic routes, Avenida Cincuentenario, connecting significant locations such as the airport. Currently, this street runs along the northern part of the archaeological site, providing better protection for the monuments against the impact of pollution.

1.3. Geological and Geomorphological Setting

The complex region formation is due to multifarious interactions among five plates: two continental, the North and South American plates, and three oceanic shelfs called Caribbean, Cocos, and Nazca. The latter one is still subducting beneath the Panamanian portion of the Caribbean Plate [26].
As it is justifiable and in line with to the statement of Cunningham et al. [27], nearly 70 percent of the isthmus consists of volcanic rocks. Observing the surroundings of Panamá Viejo, the formations present are Panamá, marine facies (tuffaceous sandstone and siltstones, algal and foraminifera limestones) and volcanic facies (agglomerates, generally andesitic in fine-grained tuffs, and streamed deposited conglomerates). Moreover, there is La Boca formation (with siltstones, sandstone, tuff, and limestones). Lastly, there are alluvium or fill sediments, along with basalts and andesites.
Focusing specifically on the Panamá Viejo site, a thesis research performed specific analysis on the geology of the archaeological site. It realized a characterization of the superficial soil in order to establish a geological pattern of the area where the colonial structures are erected [28]. The study showed the presence of a volcanic eruption on the coast near the Casas Reales complex. Specifically, the rocks, showing an aphanitic texture, are mainly andesite, displaying surface oxidation. In addition, andesitic agglomerates were detected. Finally, pyroclastic outcrops were also identified near the complex of the Torre de la Catedral. In Panama, rock outcrops are present throughout almost the entire coastal area. They can be seen by the naked eye at the archaeological site, in areas close to the cathedral, the convent of Santo Domingo, and even in Casas Reales. In both cases of Casas Reales and the Torre de la Catedral, these outcrops were used also as foundations, offering stable ground [14].

2. Materials and Methods

Among the monuments of the complex, eight structures were carefully chosen for investigation. The selection was based on their significance and with the aim of providing a comprehensive representation of the entire site, in accordance with the patronage [4,13]. For evaluating different environmental conditions, structures situated in different positions were considered, such as those near the sea, those farther away, those adjacent to roads, and those that are not. The selected monuments are outlined below, ordered from the site’s eastern side to its western side. Their respective locations are illustrated in Figure 3.
  • Fortín de la Natividad: Constructed during the 17th century on the eastern side of the site. Currently located near the new Vía Cincuentenario and in front of a gas station;
  • Convento de San Francisco: The construction began in 1603, situated in the eastern part of the archaeological site, adjacent to the new Vía Cincuentenario. It was one of the largest convents in Panamá Viejo, initially occupying around 5000 m2, which is now reduced to 3000 m2;
  • Hospital de San Juan de Dios: Initially known as the “Saint Sebastian Hospital”, built two years after the foundation of the town. Renamed San Juan de Dios from 1620 onwards, it was named after the order that took over the hospital. The original area of the convent was 2500 m2, and is now reduced to 1500 m2. It consisted of a large stonewall structure incorporating a church, cloisters, rooms, patios, and the military hospital;
  • Convento de las Monjas de la Concepción: Occupies an area of 1500 m2 on the western side of the town. The church was constructed a century later than the town’s foundation. In the 20th century, its ruins were damaged by the construction of a street perpendicular to Vía Cincuentenario, dividing the complex and the church in half;
  • Convento de la Compañía de Jesús: Established in 1578 and located near the Plaza Mayor. Originally made of wood, but from the beginning of the 17th century, the convent was converted into stone masonry. The remaining structures include the church and the primary cloisters, dating back to after the 1621 earthquake;
  • Casa Terrín: Overlooking the Plaza Mayor, this structure was constructed around 1600 by Francisco Terrín, one of the most powerful inhabitants of the town;
  • Torre de la Catedral: Functioned as a belfry and watchtower, this stone masonry tower was built between 1619 and 1626, facing Plaza Mayor;
  • Casas Reales: The most important architectural complex in the town, it held a prominent position in the public hierarchy. Built on bare rock foundations, its strategic location was the most salubrious, with a dominant position in the town and in relation to the sea. The complex was subjected to constant remodeling after it was seriously damaged during the 1621 earthquake. Following the town’s abandonment, the walls endured tidal erosion.
The sampling procedure was performed according to the UNI EN 16085:2012 norm [29], European standard, equivalent to the UNE-EN 16085:2014 already utilized in Latin America [30]. The collection of the specimens was performed in agreement with the indications of the patronage experts, with original material being selected that was not altered by restoration, in order to have the most complete representativeness of all the lithotypes utilized in the masonry. Furthermore, sampling points were chosen on the basis of particular deterioration phenomena, visually detected, in order to evaluate the environmental impact. Finally, possible quarries at the site were also identified and sampled. Specifically, twenty-four samples from the masonry of eight monuments and three samples from outcrops were collected and listed in Table 1.
In order to characterize and evaluate the state of preservation of these materials, the following analyses were performed:
-
Stereomicroscope observations were performed by an Optika SZ6745TR, equipped with a webcam, MOTICAM 2005 5.0 Mp,. The Moticam Image Plus 2.0 software was utilized for preliminary analyses of the bulk samples;
-
Polarized light microscopy (PLM) was utilized for the observation of the thin sections, using an Olympus BX 51 microscope, equipped with scanner and the MICROMAX software “Primoplus_32” vers. 8.11.02;
-
X-ray powder diffraction (XRPD) was used for determining the mineralogical phases present, through a Philips PW 1730 diffractometer equipped with a copper anticathode and a nickel filter. The measurement conditions had a diffraction interval of 2θ, between 5° and 50°, a 2°/minute step at 40 kV voltage, and a 30 mA current intensity. In addition, further analyses were performed in order to verify the clay minerals present in several samples, utilizing a Bruker AXS D8, in Bragg–Brentano geometry, equipped with a X-ray tube and a SolX solid state detector, working in low-temperature through a Peltier cooling system. The samples for this technique underwent the powdering process, utilizing two mills: firstly, a jaw crusher and secondly a mortar grinder with agate jar and pestle. For materials with a high hardness, the process was finished by manual grinding with an agate mortar. Moreover, in order to examine the clay minerals in detail with the second diffractometer, analyses were repeated three times for each sample: the first one on a random mount sample (measurement conditions: time = 2 h 14′; slits = 1, 1, 0.2); then on iso-oriented powder (measurement conditions: time = 1 h 33′; slits = 0.6, 0.6, 0.2; 2θ = 2–30°); and finally, the latter one underwent ethylene glycol solvation (measurement conditions: time = 1 h 33′; slits = 0.6, 0.6, 0.2; 2θ = 2–30°).
-
Environmental scanning electron microscopy and microchemical investigations by energy dispersive X-ray spectrometry (ESEM-EDS) were carried out to determine the elemental composition of specific areas of interest, already observed in the PLM investigation. The instrument utilized was a ZEISS EVO LS 10 with LaB6 source;
-
X-ray fluorescence (XRF) on powder pellets (see the XRPD section for the powdering process), using a wavelength-dispersive automated ARL Advant’X spectrometer, was utilized. The accuracy and precision for major elements were estimated to be 2–5%; for trace elements (above 10 ppm), they were above 10%;
-
X-ray Fluorescence non-invasive micro-analysis (µXRF) performed using an ARTAX 200 μEDXRF spectrometer equipped by Mo X-ray tube and using a Peltier cooled Si (Li) detector, with a collimator with a diameter from 1 mm, a voltage of 50 kV, and a current of 700 μA (live time: 300 s), on bulk samples in order to evaluate the nature of the chromatic alterations;
-
Mercury intrusion porosimetry (MIP) was used for understanding the porosimetry features of the materials and the index of their state of conservation, using a porosimeter “PASCAL 240, THERMO SCIENTIFIC”;
-
Ion chromatography (IC) was used in order to evaluate the possible presence of soluble salts present in the masonry. IC analyses were performed using a DIONEX ICS 900. Anions analysis: Column S23 Pre-column G23; Cations analysis: Column CS12 Pre-column CG12.

3. Results and Discussion

3.1. Materials Characterization—Outcrops

Three outcrops, i.e., potential quarries, were identified at the site. Specifically, polygenic breccia, mainly composed of volcanic clasts, and basaltic andesite are the lithotypes detected.
In proximity of the Casas Reales complex, near the sea side, two outcrops, one of breccia and one of basaltic andesite, were sampled (Figure 3g). These findings are in agreement with a previous investigation by Grajales Saavedra [28], which identified andesite and agglomerates outcrops in this area. Another outcrop of basaltic andesite was found near the Convento de Santo Domingo and the Plaza Mayor, in the southern part of the site. This outcrop showed digging traces, as shown in Figure 3h; therefore, it is feasible that it was a quarry.
Polarized light microscopy (PLM) observations showed that the volcanoclastic breccia is mainly characterized by pyroxenes clusters and amygdales filled with secondary minerals due to hydrothermal phases. The basaltic andesites showed the presence of pyroxenes clusters, zoned plagioclases, several amygdales with secondary minerals, and traces of hydrothermal activity.

3.2. Materials Characterization—Masonry

Through the preliminary macroscopic observations of the masonry, sedimentary and volcanic rocks were identified. These findings are in agreement with previous studies that identified these rock types as construction materials [33,34].
Mineralogical and petrographic characterization highlighted that the most diffused lithotype is polygenic breccia, which is present in nearly all of the sampled monuments. The breccia’s origin is related to sedimentary processes. In this case, the sediments produced fragments of both volcanogenic and marine origin. Additionally, volcanic rocks, such as basaltic andesite, rhyolite, and tuffite, were found as well.
In more detail, when observing thin sections of polygenic breccias under polarized light microscopy (PLM), clasts deriving from effusive rocks (such as andesites and basalts) and from marine fossils (such as foraminifera, corals, echinoderms, etc.) were detected. In addition, microscopic analysis identified several inner alterations of the volcanogenic fragments. Plagioclases exhibiting zonation and/or sericitization, features associated with hydrothermal alteration, were observed. These alterations derive from the stone formation process [35]. Furthermore, in almost all samples of tuffite and volcanic clasts within breccias, a diffused zeolitization was detected. Lastly, a few samples (PV FC 6, PV FC 9, and PV SJdD), showing a very fine texture and a creamy aspect under the naked eye, were recognized as altered volcanic rocks. Examples of PLM micrographs are shown in Figure 4.
In order to more precisely classify the lava stones, X-ray fluorescence (XRF) analysis was performed, confirming the presence of basaltic andesites, rhyolites, and determining the altered volcanic rocks as rhyodacites (Figure 5 and Figure 6).
Specifically, masonry mainly composed of polygenic breccias was identified at the Convento de las Monjas de la Concepción, Convento de la Compañia de Jesús, and Casas Reales. At the Fortín de la Natividad, the stones detected were polygenic breccia and basaltic andesite. Furthermore, at the Convento de San Francisco, both polygenic breccia and rhyodacite were identified. Rhyodacite was also detected at the Hospital de San Juan de Dios. The Torre de la Catedral was predominantly composed of tuffite, while the wall examined at the Casa Terrín complex was entirely constructed from rhyolite.
It was observed that this rhyolite was characterized by sanidine alteration and the presence of iron oxides and/or hydroxides. These formations have a reddish hue, which is often observed to be more concentrated in the external part of the specimens. These alterations were also detected in polygenic breccias and in rhyodacites (e.g., Figure 4c). In sample PV CT 1, a rhyolite fragment, different oxidation in the outer part and the inner part was clearly visible to the naked eye. Non-invasive X-ray fluorescence micro-analysis showed the different intensity of the Fe peak, highlighting higher external oxidation (Figure 7).
Contextually, X-ray powder diffraction analysis was performed on almost all samples, with the exception of specimens that exhibited an insufficient amount of material to carry out all the analyses planned. Nevertheless, each rock typology was studied, confirming and/or clarifying the previous investigations and obtaining a complete representation of the mineralogy of the lithotypes under study. In Table 2, the results of the X-ray powder diffraction (XRPD) analysis are summarized, with the crystallographic phases identified in each rock, showing a representative sample per type.
Thanks to this investigation, traces of hematite were confirmed within the rhyolite, in addition to traces of kaolinite, a possible symptom of an initial hydrothermal alteration process of the stone and/or weathering during the rock formation [39,40]. Moreover, the aforementioned zeolitization process, observed in breccias and tuffites, was confirmed, detecting clinoptilolite and mordenite. These zeolites were demonstrated to be the main product of alteration caused by hydrothermal processes on vitric tuffs and perlites [41,42]. The rhyodacite samples are characterized by clinoptilolite as the dominant phase (PV FC 9 and PV SJdD) and mordenite (PV FC 6) as the abundant phase, followed by the presence of feldspars.
The finding of clinoptilotite is also in accordance with that of Mumpton [43], who stated that, in Panama, clinoptilolite is one of the most diffused zeolites in rocks originating from volcanic sediments. The presence of zeolites in altered volcanic tuffs is widespread across Latin America. These zeolites give softness to the stone, making them easily workable and lightweight. These features have made them common construction materials for centuries in Central America [44,45,46], such as in Mexico, at the Mayan pyramids at Monte Alban and Mitla. Moreover, in this latter example, the pyroclastic sediments show the presence of abundant mordenite and clinoptilolite formed by the alteration of pre-existing glass shards [44], as is also assumable for our samples.
The zeolitized areas underwent scanning electron microscopy and energy dispersive X-ray spectrometry (ESEM-EDS) analysis, performed on thin sections, confirming the previous results obtained by PLM observations and the X-ray powder diffraction (XRPD) analysis. Moreover, in these areas, this investigation identified the possible presence of iron oxides, since the zeolites can exchange ferrous and ferric ions [47], and of silicates of Al, Mg, and Fe attributable to chlorite. In addition, amygdaloidal structures detected in the basaltic andesites were also investigated, revealing that they were mainly filled with radial aggregate of chlorite. This is another mineral that can result from hydrothermal modifications from primary Fe-Mg minerals, such as mica, pyroxene, amphibole, garnet, and olivine. Nevertheless, the formation of chlorite can also be caused by weathering of these mineral precursors [48].

3.3. Evaluation of the State of Conservation

In situ macroscopic analyses allowed us to carry out a first analysis of the deterioration phenomena, summarized in Figure 8.
On tuffites and polygenic breccias of the masonries, and in an outcrop of basaltic andesite, black patinas were observed by the naked eye. Then, they were investigated under stereo and scanning electron microscopy, revealing bio-deterioration activity, ascribable to cyanobacteria colonization (Figure 9).
The presence of black algae on these monuments was already observed in the work of Torres Montes [33], where “alga negra”, a cyanobacteria (Oscillatoria sp.) [49], was described. The algal presence is facilitated by the bio-receptivity of the substrate, determined by features such as porosity, surface roughness, and hygroscopicity [50]. These characteristics can also indicate a material prone to wettability. Considering the impact on the stone, the “alga negra” does not represent a direct danger for the material, but it can be a substrate for other bio-deteriogens, and it can trap and retain pollutants. Furthermore, it suggests the presence of high moisture.
On rhyolite and rhyodacite, lichens were observed. These deteriogenic organisms can damage the stone substrate through the production of oxalic acid and other organic acids.
Both macroscopic and microscopic analyses showed the presence of chromatic alteration due to external oxidation, such as iron oxides detected in rhyolites and rhyodacites. These areas represent possible aesthetical damage. Moreover, they could represent a potential point of differential deterioration phenomena, since they show different physical-chemical features in comparison with the core of the rock.
In addition, the presence of clay minerals, in particular montmorillonite and vermiculite, and zeolites can contribute to a significant sensitivity to expansional processes due to the moisture cycles and salt crystallization [51]. Furthermore, microscopic analyses showed that altered parts (such as zeolitized areas) can feature cracks. These aspects can be co-responsible for the observed macroscopic weathering phenomena, such as cracks, flaking, exfoliation, and detachments.
The rhyodacite of the PV SJdD sample, mainly formed by clinoptilotite—M3-6(Si30Al6) O72 · 20H2O, where M = Ca, K or Na [52]—showed a detached part. Along the internal surface, a whitish patina was identified as well (Figure 10). Under polarized light microscopy (PLM), the aspect was irregular, showing decohesion and a different thickness. The mechanical stress due to the reaction process, responsible for the patina formation, is clearly visible by scanning electron microscopy (ESEM) (Figure 10b). In addition, the microchemical investigation, performed by energy dispersive X-ray spectrometry (EDS), identified Ca as the principal element present in the patina, also with the presence of O, suggesting a composition mainly formed by calcium carbonate (Figure 10c). The development of calcite, as a precipitated secondary mineral, was also supported by its identification in the masonry mortars previously studied [13].
Analyzing the samples using mercury intrusion porosimetry (MIP), it was noticed that all the samples showed an average pore diameter of less than 0.2 μm, which is the threshold for micropores. Considering the accessible porosity, tuffite and rhyodacite registered the highest values: between 26% and 31%. Polygenic breccia showed variability from approximately 12% to 29.5%; while basaltic andesite and rhyolite had the lowest values, equal to or less than 12%. Detailed results are shown in Table 3.
From a preservation point of view, the porous structure could potentially increase the substrate’s bio-receptivity, as previously mentioned. Furthermore, it can undergo possible salt damage, due to the dissolution/crystallization cycles. The salt’s solubility and crystallization pressure on the pore walls can be influenced by the size of the pore [53]. The produced stress can cause several forms of damage, depending on where the crystallization occurs. For instance, salt sub-florescence, occurring within the porous stone, can lead to higher decay compared to efflorescence, where the crystallization takes place on the stone’s surface [54,55]. The mobility of saline solutions within the material is regulated by several factors. These factors include the structural characteristics of the stone, such as the open porosity, pore size distribution and connectivity, the mechanical and petrographic features, and salt concentration [56].
In order to investigate the possible presence of soluble salts, ion chromatography (IC) analysis was performed on samples showing alteration patinas. The highest values registered belonged to calcium, followed by chloride and sodium, nitrate, sulphate, magnesium, and, rarely, acetate and potassium. Concerning anions, the chloride, nitrate, and sulphate concentration was always <2%, as reported in Table 4, which displays the IC data. The low concentration found explains why salts were not detected by X-ray powder diffraction (XRPD), which has a detection limit of <3–4%.
Considering the Panamanian thermo-hygrometric conditions and the ions detected, possible salt compounds that can crystallize in these circumstances were identified and reported in Table 5, according to the studies of Arnold and Zehnder [23]. For instance, chlorides and nitrates of potassium and sodium, as well as sodium and magnesium sulphates, can be formed under these conditions, since these compounds crystallize easily in humid climates. Considering the potential origin, the presence of halite is feasible due to the proximity with the sea. While sulphates and nitrates can derive from both natural and anthropogenic sources, such as pollution, other building materials and rising damp should also be considered [56,57]. Hydratable salts, such as mirabilite and thernadite, can cause salt weathering caused by the change of volume. Possible pathologies due to their action are decohesion, alveolation, flaking, scaling, and delamination, all phenomena visible in Figure 8 [56].
Lastly, in the presence of water, the ions can create an aggressive environment, forming acids, such as hydrochloric, sulfuric, or nitric acid. The chemical action of these compounds can cause the dissolution of carbonate-based stones and mortars [13]. The calcite of secondary precipitation can crystallize within pores (causing internal tensions) and/or on the surface. This can form superficial patinas, such as the one previously observed in Figure 10, and salt encrustations, as shown in Figure 8.

4. Conclusions

The aim of this research work was to thoroughly characterize the stone masonry structures and assess their vulnerability to environmental impact at the UNESCO “Monumental site of Panamá Viejo”, located in Panama. For this objective, the identification of the various lithotypes was performed and their state of conservation was analyzed. In addition, potential quarries for the supply of raw materials were identified.
Nowadays, the site hosts buildings constructed during the period between the end of the 16th century and the following century. This study selected eight stonework masonry monuments, which belong to monastic complexes and public and private constructions with a particular and/or strategic function.
Through the analyses performed, stereo, polarized light (PLM) and electronic microscopy (ESEM-EDS), X-ray powder diffraction (XRPD), and X-ray fluorescence (XRF), it was possible to realize a classification of the lithotypes present in the monuments under study. The results revealed that the masonry structures are mainly composed of sedimentary rocks, such as polygenic breccia, formed by fragments of both volcanic and marine origin. Volcanic rocks were also identified, specifically tuffite, rhyodacite, basaltic andesite, and rhyolite. Considering the outcrops, basaltic andesite and breccia, mainly formed by volcanic clasts, were detected.
Concerning the state of conservation, bio-deteriogens were observed, such as black algal patina, potentially a cyanobacteria (Oscillatoria sp.). This was mostly diffused on the tuffite and breccia masonry. Furthermore, it was observed on basaltic andesite from an outcrop. On the rhyolite and rhyodacite samples, lichens were detected. Both these organisms potentially represent a source of damage for the stone. Lichens can cause damage through the production of oxalic acid and other organic acids. Considering the black alga, it does not represent a direct danger for the stone, but it can act as a substrate for other bio-deteriogens, and it can trap and retain pollutants. Furthermore, it can be indicative of a high moisture presence and of a material prone to wettability.
The bio-receptivity of the substrate can also be determined by other factors, such as its porosity, studied through mercury intrusion porosimetry (MIP) analysis. Additionally, the porous structure can be affected by salt damage, due to the dissolution/crystallization cycles. Therefore, ion chromatography (IC) investigations were performed in order to determine the potential soluble salts present in the samples. Considering the results and the Panamanian environmental conditions, the formation of chlorides and nitrates of potassium and sodium is feasible, as the formation of sodium and magnesium sulphates. The salt weathering due to hydratable salts can cause mechanical stress within the structure. This can cause decohesion, alveolation, flaking, scaling, and delamination, all phenomena visible in the studied monuments. In addition, in presence of water, the ions can chemically affect the structure, forming an acid environment. This can cause the dissolution of carbonate-based stones and mortars. In fact, the crystallization of secondary calcite was observed.
A further potential source of mechanical stress is the presence of clay minerals and zeolites, detected by PLM, scanning electron microscopy and energy dispersive X-ray spectrometry (ESEM-EDS) and XRPD investigations. These materials are susceptible to moisture cycles. They can undergo expansional–shrinking processes, contributing to cracks, flaking, exfoliation, and detachments.
Lastly, chromatic alteration was observed. This is due to an oxidation process, such as those related to the iron oxides detected in the outer part of rhyodacite and rhyolite samples. These areas represent aesthetic damage; furthermore, they can undergo differential deterioration phenomena, since they show different physical-chemical features in comparison with the core of the rock.
In conclusion, this work represents a fundamental step for the current and future preservation of this site. Indeed, it represents an instrument for organizing and enhancing the maintenance and restoration works. It allows the operators aimed at preserving the site to know the compositions of the building materials and to understand the problems related with their interaction with the environment. Moreover, it helps limit and prevent the causes of damages, having identified them. In addition, it can be used in the selection of the most suitable and compatible restoration materials, such as consolidants, protective treatments, restoration mortars, etc. Lastly, it will aid in choosing the most similar materials for possible replacements/integrations in the masonries, utilizing the outcrops identified.

Author Contributions

Conceptualization, C.C., A.B., S.I.A.D. and C.V.; methodology, C.C., A.B., S.I.A.D. and C.V.; validation A.B. and C.V.; formal analysis, C.C.; investigation C.C., A.B., S.I.A.D. and C.V.; resources, A.B., C.V. and S.I.A.D.; data curation, C.C.; writing—original draft preparation, C.C.; writing—review and editing, A.B., S.I.A.D., C.V. and C.C.; visualization, C.C.; supervision, A.B., S.I.A.D. and C.V.; project administration, A.B. and S.I.A.D.; funding acquisition, A.B., C.V. and S.I.A.D. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data Availability Statement

Not applicable.

Acknowledgments

The authors kindly acknowledge all the people of the Patronage of Panama Viejo, of the Institute of Atmospheric Sciences and Climate of the Italian National Research Council (ISAC-CNR) and the Department of Physics and Earth Sciences of the University of Ferrara (Italy) for the support, encouragement, and collaboration for the realization of this study. In particular, for the support in performing the analysis, the authors want to thank Annalisa Martucci, Renzo Tassinari, Sabrina Russo, Salvatore Pepi, Franco Corticelli and Orlando Favoni. Finally, for the sampling collection, a special thank goes to Alessandro Sardella and Giacomo Dondi.

Conflicts of Interest

The authors declare no conflict of interest.

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Figure 1. Google Earth-modified image of the Monumental Complex of Panamá Viejo, surrounded by the urban context of Panama City. The dashed line indicates the current path of the Avenida Cincuentenario.
Figure 1. Google Earth-modified image of the Monumental Complex of Panamá Viejo, surrounded by the urban context of Panama City. The dashed line indicates the current path of the Avenida Cincuentenario.
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Figure 2. Walls of the Casas Reales Complex. The bottom part still shows the erosion due to the tides “carving” effect.
Figure 2. Walls of the Casas Reales Complex. The bottom part still shows the erosion due to the tides “carving” effect.
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Figure 3. (a) Google Earth-modified image of the monumental complex of Panamá Viejo and list of the monuments and outcrops sampled with their locations. (b–f) Monuments sampled and examples of specimens collected: (b) Fortín de la Natividad; (c) Convento de San Francisco, (d) Convento de las Monjas de la Concepción; (e) Torre de la Catedral; (f) Casa Terrin; (g) outcrop sampled near Casas Reales Complex; (h) outcrop showing traces of possible quarrying activities near the Convento de Santo Domingo.
Figure 3. (a) Google Earth-modified image of the monumental complex of Panamá Viejo and list of the monuments and outcrops sampled with their locations. (b–f) Monuments sampled and examples of specimens collected: (b) Fortín de la Natividad; (c) Convento de San Francisco, (d) Convento de las Monjas de la Concepción; (e) Torre de la Catedral; (f) Casa Terrin; (g) outcrop sampled near Casas Reales Complex; (h) outcrop showing traces of possible quarrying activities near the Convento de Santo Domingo.
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Figure 4. Micrographs of thin sections of samples observed by polarized light microscopy (PLM)- cross-polarized light (xpl): (a) PV FN 5 sample: altered pyroxene cluster, amygdale filled with secondary minerals, in a basaltic andesite; (b) PV FC 7 sample: foraminifera bioclast, quartz, plagioclase and pyroxenes fragments in a polygenic breccia; (c) PV FC 9 sample: a chalcedony filling an amygdale, surrounded by iron oxides in an altered volcanic rock; (d) PV CT 2 sample: sanidine and metal oxides in a rhyolite; (e) PV TC 4 sample: diffused zeolitization in a tuffite; (f) PV CC 4 sample: fragments of basaltic/andesitic lithoclasts in a breccia.
Figure 4. Micrographs of thin sections of samples observed by polarized light microscopy (PLM)- cross-polarized light (xpl): (a) PV FN 5 sample: altered pyroxene cluster, amygdale filled with secondary minerals, in a basaltic andesite; (b) PV FC 7 sample: foraminifera bioclast, quartz, plagioclase and pyroxenes fragments in a polygenic breccia; (c) PV FC 9 sample: a chalcedony filling an amygdale, surrounded by iron oxides in an altered volcanic rock; (d) PV CT 2 sample: sanidine and metal oxides in a rhyolite; (e) PV TC 4 sample: diffused zeolitization in a tuffite; (f) PV CC 4 sample: fragments of basaltic/andesitic lithoclasts in a breccia.
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Figure 5. TAS (Total Alkali/Silica) classification [36]. ○ = masonry samples; ◊ = outcrop samples.
Figure 5. TAS (Total Alkali/Silica) classification [36]. ○ = masonry samples; ◊ = outcrop samples.
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Figure 6. Winchester and Floyd [37] classification for altered volcanic rocks. ◊ = masonry samples.
Figure 6. Winchester and Floyd [37] classification for altered volcanic rocks. ◊ = masonry samples.
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Figure 7. Spectra obtained by X-ray fluorescence non-invasive micro-analysis (µXRF) of the PV CT 1 sample. From the outer side (spectrum 1) to the inner part (spectrum 3).
Figure 7. Spectra obtained by X-ray fluorescence non-invasive micro-analysis (µXRF) of the PV CT 1 sample. From the outer side (spectrum 1) to the inner part (spectrum 3).
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Figure 8. Examples of stone deterioration patterns, according to [32], at the monumental site of Panamá Viejo.
Figure 8. Examples of stone deterioration patterns, according to [32], at the monumental site of Panamá Viejo.
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Figure 9. (a) Stereo photomicrograph of PV TC 4 sample, showing a superficial black algal patina; (b) Scanning electron microscopy (ESEM) photomicrographs (left: secondary electrons detector-SE; right: backscattered electrons detector-BSD) of PV TC 4 sample, detail of the superficial black algal patina.
Figure 9. (a) Stereo photomicrograph of PV TC 4 sample, showing a superficial black algal patina; (b) Scanning electron microscopy (ESEM) photomicrographs (left: secondary electrons detector-SE; right: backscattered electrons detector-BSD) of PV TC 4 sample, detail of the superficial black algal patina.
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Figure 10. Thin section of the PV SJdD sample showing an altered patina: (a) PLM-xpl micrograph; (b) ESEM micrograph; (c) ESEM-energy dispersive X-ray spectrometry (EDS) microchemical compositional maps.
Figure 10. Thin section of the PV SJdD sample showing an altered patina: (a) PLM-xpl micrograph; (b) ESEM micrograph; (c) ESEM-energy dispersive X-ray spectrometry (EDS) microchemical compositional maps.
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Table 1. Samples, lithotypes (for the definition of breccia see [31]), deterioration patterns [32], location of sampling, pictures and analyses performed. Samples are grouped by structure, while structures are listed from the eastern side to the western side of the site. Legend: SM = stereo microscopy; PLM = polarized light microscopy; ESEM-EDS = environmental scanning electron microscopy and energy dispersive X-ray spectrometry; ts = on thin section; bm = on bulk material; XRPD = X-ray powder diffraction; XRF = X-ray fluorescence; µXRF = X-ray fluorescence non-invasive micro-analysis; MIP = mercury intrusion porosimetry; IC = ion chromatography.
Table 1. Samples, lithotypes (for the definition of breccia see [31]), deterioration patterns [32], location of sampling, pictures and analyses performed. Samples are grouped by structure, while structures are listed from the eastern side to the western side of the site. Legend: SM = stereo microscopy; PLM = polarized light microscopy; ESEM-EDS = environmental scanning electron microscopy and energy dispersive X-ray spectrometry; ts = on thin section; bm = on bulk material; XRPD = X-ray powder diffraction; XRF = X-ray fluorescence; µXRF = X-ray fluorescence non-invasive micro-analysis; MIP = mercury intrusion porosimetry; IC = ion chromatography.
SampleLithotypeDeterioration PatternsSampling LocationPictureAnalyses Performed
PANAMÁ VIEJO—Masonry
1.
Fortín de la Natividad
PV FN 1BrecciaBiological colonization (algae), partial detachment (exfoliation)S wall—External part, h 100 cm Heritage 06 00341 i001PLM; XRPD; ESEM-EDS (ts); XRF; IC
PV FN 2BrecciaNo evident deterioration was detectedS wall—External part, h 20 cm Heritage 06 00341 i002PLM; XRPD; XRF; MIP
PV FN 4Basaltic andesite Partial erosionW wall—Inner part, h 102 cm Heritage 06 00341 i003PLM; ESEM-EDS (ts); XRPD; XRF; MIP
PV FN 5Basaltic andesite No evident deterioration was detectedInner part of the Fortress, ground levelHeritage 06 00341 i004PLM; XRPD; XRF; MIP
2.
Convento de San Francisco
PV FC 4BrecciaNo evident deterioration was detectedE wall of the navy, ground levelHeritage 06 00341 i005PLM; ESEM-EDS (ts); XRPD; XRF; MIP
PV FC 5BrecciaExfoliation.E wall of the navy, h 106 cmHeritage 06 00341 i006PLM; XRPD; IC
PV FC 6RhyodacitePartial delamination and discolorationE wall of the Convent, h 170 cmHeritage 06 00341 i007PLM; ESEM-EDS (ts); XRPD; XRF; MIP; IC
PV FC 7BrecciaExfoliation, differential erosion/covingW wall, h 175 cmHeritage 06 00341 i008PLM; ESEM-EDS (ts); XRPD; XRF
PV FC 8BrecciaExfoliation, differential erosion/alveolization, biological colonization (algae)W wall, h 100 cmHeritage 06 00341 i009PLM; XRPD; XRF; IC
PV FC 9RhyodaciteExfoliation, differential erosion/alveolization, partial biological colonization (algae)W wall, h 200 cmHeritage 06 00341 i010PLM; XRPD; XRF; IC
PV FC 11BrecciaBlackening/biological colonization (algae)S-W side of the wall of the complex 9.70 m from the new via Cinquentenario, h 140 cmHeritage 06 00341 i011PLM; XRPD; XRF; IC
3.
Hospital de San Juan de Dios
PV SJdDRhyodaciteBiological colonization (lichens) and a whitish thin-encrustation on the internal surfaceWall facing the old Via Cinquantenario, h 120–130 cmHeritage 06 00341 i012PLM; ESEM-EDS (ts); XRPD
4.
Convento de las Monjas de la Concepción
PV CC 4BrecciaDifferential erosion/covingN side of the chapel, h 140 cmHeritage 06 00341 i013PLM; XRPD; XRF; MIP
PV CC 5BrecciaErosion, biological colonization (algae)N wall of the nave, h 365 cmHeritage 06 00341 i014PLM; XRPD; XRF
PV CC 6BrecciaDifferential erosion/coving, biological colonization (algae)Outer wall of the Church, near an eaves, faced S and exposed to the old Via Cinquantenario, h 165–170 cmHeritage 06 00341 i015PLM; XRPD; XRF; IC
5.
Convento de la Compañia de Jesús
PV JC 1BrecciaNo evident deterioration was detected (previously covered by plaster, noticed also a bush-hammered surface)W façade, internal side, inner part of the arch, h 345 cmHeritage 06 00341 i016PLM; XRPD; XRF; MIP
PV JC 2BrecciaBiological colonization (algae), probably bush-hammeredW façade, internal side, inner part of the arch, h 300 cmHeritage 06 00341 i017PLM; XRPD; XRF
PV JC 3BrecciaNo evident deterioration was detectedNear the N façade, ground levelHeritage 06 00341 i018PLM; XRPD; XRF; MIP (2 specimens for MIP analysis have been obtained, thus the results’ labels show a and b)
PV JC 4BrecciaNo evident deterioration was detectedW wall, h 293 cmHeritage 06 00341 i019PLM; XRPD; XRF; MIP; IC
6.
Casa Terrin
PV CT 1RhyoliteBiological colonization (lichens) and discoloration (?).Wall on the W side of Casa Terrin. Sample collected from the N side, h 165 cmHeritage 06 00341 i020SM; PLM; XRPD; XRF; µXRF; MIP
PV CT 2RhyoliteNo evident deterioration was detectedWall on the W side of Casa Terrin. Sample collected near the S-E corner, ground levelHeritage 06 00341 i021PLM; XRPD; XRF; MIP
7.
Torre de la Catedral
PV TC 3TuffiteExfoliationW wall, h 109 cmHeritage 06 00341 i022PLM; XRPD; XRF; MIP
PV TC 4TuffiteBiological colonization (black algae)S wall, h 127 cmHeritage 06 00341 i023SM; PLM; ESEM-EDS (bm); XRPD; XRF; MIP; IC
8.
Casas Reales
PV CR 4BrecciaBiological colonization (algae), erosion/delaminationS wall, h 160 cmHeritage 06 00341 i024PLM; XRPD; XRF; IC
PANAMÁ VIEJO—Outcrops
PV Q 1Breccia (volcanoclastic)Biological colonization (black algae)Outcrop near Casa RealesHeritage 06 00341 i025PLM; MIP
PV Q 2Basaltic andesite Biological colonizationQuarry near the Santo Domingo ConventHeritage 06 00341 i026PLM; XRPD; XRF; MIP
PV vic. CR Basaltic andesite Biological colonization (black algae)Outcrop near Casa Reales-Location: Lat. 9°0′20.720″–Long.–79°29′0728″Heritage 06 00341 i027PLM; XRPD; XRF; MIP
Table 2. Legend: Cal: calcite; Fsp: feldspar; Px: pyroxenes; Qtz: quartz; Zeo: zeolite; Hem: hematite; Kln: kaolinite; Mnt: montmorillonite; Vrm: vermiculite [38]. +++ = dominant; ++ = abundant; + = present, traces; - = absent.
Table 2. Legend: Cal: calcite; Fsp: feldspar; Px: pyroxenes; Qtz: quartz; Zeo: zeolite; Hem: hematite; Kln: kaolinite; Mnt: montmorillonite; Vrm: vermiculite [38]. +++ = dominant; ++ = abundant; + = present, traces; - = absent.
Lithology e.g., SampleCalFspPxQtzZeoHemKlnMntVrm
Basaltic andesitePV FN5-+++++----tr/+-
RhyolitePV CT1-+/++-+++-trtr--
RhyodacitePV FC6-++-++++++----
Polygenic BrecciaPV FC7+++++-+++---tr
TuffitePV TC4++++++++++----
Table 3. Data of porosity and pore diameter (Ø) of the different samples, gathered in accordance with the same rock typology.
Table 3. Data of porosity and pore diameter (Ø) of the different samples, gathered in accordance with the same rock typology.
Accessible PorosityInaccessible PorosityAverage Pore ØMedian Pore ØModal Pore Ø
LithotypeSample%%μmμmμm
PolygenicPV CC 421.210.160.110.603.31
brecciaPV FC 412.320.090.060.090.05
PV FN 225.900.050.100.190.14
PV JC 124.090.010.080.150.19
PV JC 3A27.090.020.110.702.44
PV JC 3B22.430.140.060.110.13
PV JC 415.960.330.040.050.06
PV Q 129.521.920.130.381.16
TuffitePV TC 330.700.250.100.330.82
PV TC 426.501.110.110.270.47
BasalticPV FN 410.520.160.060.170.04
andesitePV FN 512.140.080.070.220.29
PV Q 211.510.020.050.140.20
PV vic. CR5.231.320.050.080.06
RhyolitePV CT 111.570.230.130.200.22
PV CT 210.310.480.100.160.17
RhyodacitePV FC 627.390.150.050.070.06
Table 4. Anion and cation concentrations (ppm) in Panama Viejo samples.
Table 4. Anion and cation concentrations (ppm) in Panama Viejo samples.
Lithology SampleC2H3O2−PO43−C2O4=CHO2−NO2−NO3−SO4−Cl−NH4+K+Mg2+Na+Ca2+
Polygenic Breccia PVFN187026811118382211125732534310,0760
PVFC5703193702585764992524428920772490
PVFC8642244201294435651912319911783038
PVFC111400531671736408935436957319,930
PVCC617703701155723820224112385027,884
PVJC430031113551284838210015287341
PVCR 46012256391625792731482324348845
TuffitePVTC 4003475626352309810,67599237294530633,039
RhyodacitePVFC 6419901727103377517392525028815181787
PVFC 9108814304126105163413343524435336721775
Table 5. Equilibrium thresholds of RH (%) and T (°C) of some soluble salts that can affect the masonry. Here, we selected the T (°C) range and highlighted the RH values that are most suitable for Panama according to Arnold and Zehnder [23].
Table 5. Equilibrium thresholds of RH (%) and T (°C) of some soluble salts that can affect the masonry. Here, we selected the T (°C) range and highlighted the RH values that are most suitable for Panama according to Arnold and Zehnder [23].
Salt Temperature (°C)
NameFormula202530
Panamanian rangeNitratiteNaNO375.474.373.1
HaliteNaCl75.575.375.1
ThenarditeNa2SO48282.884.3
SylviteKCl85.184.383.6
EpsomiteMgSO4 •7H2O90.188.388
NatronNa2CO3 •10H2O97.988.283.2
MirabiliteNa2SO4 •10H2O93.691.487.9
NiterKNO394.693.692.3
ArcaniteK2SO497.697.397
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MDPI and ACS Style

Ciantelli, C.; Arroyo Duarte, S.I.; Vaccaro, C.; Bonazza, A. Characterization of the Stone Masonries and Evaluation of the Environmental Impact in Panamá Viejo: A Contribution for the Conservation of the Monumental Complex. Heritage 2023, 6, 6526-6546. https://doi.org/10.3390/heritage6100341

AMA Style

Ciantelli C, Arroyo Duarte SI, Vaccaro C, Bonazza A. Characterization of the Stone Masonries and Evaluation of the Environmental Impact in Panamá Viejo: A Contribution for the Conservation of the Monumental Complex. Heritage. 2023; 6(10):6526-6546. https://doi.org/10.3390/heritage6100341

Chicago/Turabian Style

Ciantelli, Chiara, Silvia I. Arroyo Duarte, Carmela Vaccaro, and Alessandra Bonazza. 2023. "Characterization of the Stone Masonries and Evaluation of the Environmental Impact in Panamá Viejo: A Contribution for the Conservation of the Monumental Complex" Heritage 6, no. 10: 6526-6546. https://doi.org/10.3390/heritage6100341

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