The Use of Dolostone in Historical Buildings of Coimbra (Central Portugal)

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Article The Use of Dolostone in Historical Buildings of Coimbra (Central Portugal)

Lidia Catarino 1,2,* , Roque Figueiredo 2, Fernando Pedro Figueiredo 1,2, Pedro Andrade 1,2 and João Duarte 1 1 Geosciences Center, University of Coimbra, 3030-074 Coimbra, Portugal 2 Department of Earth Sciences, University of Coimbra, 3030-074 Coimbra, Portugal * Correspondence: [email protected]; Tel.: +351-239860530

Received: 20 June 2019; Accepted: 30 July 2019; Published: 1 August 2019

Abstract: In this paper, the importance of the dolostone (a carbonate sedimentary rock where the dominant carbonate mineral is dolomite) in monuments and urban buildings of the city of Coimbra, Portugal, is highlighted. Old quarries are not visible in the nucleus of the city, due to the sequential occupation by houses, and can only be identiﬁed by documentation (draws, contract letters and purchase orders). However, on the southern side of Mondego River (Santa Clara) some outcrops can be observed and were exploited until the mid-20th. It is presented a list of the old quarries and monuments made with this rock. The characterization of dolostones from the Coimbra Formation is also presented. It is made the connection between the local geology and the “identity” of Coimbra, putting in evidence the stone as a symbol that characterize the gilded aspect of the buildings. For restoration and rehabilitation works, a small number of blocks could be extracted from the Carvalhais quarry if were eventually necessary.

Keywords: dolostone; quarries; Coimbra Formation; heritage

1. Introduction Ever since the beginning of humanity, stone has always been an essential and emblematic element, constituting one of the supports for the development of society, including its connection to the discovery and control of fire by Homo Erectus, as well as the first utensils used for hunting and gathering food. With the Neolithic Revolution humankind stopped the hunter-gatherer lifestyle adopting sedentary habits, giving rise to great technological advances, one of the most important aspects being the establishment of and in communities. Over time, this new form of organization gave rise to the concept of state, and to the development of large cities, which would become major commercial centers [1]. With this evolutionary explosion, the demand for geological resources became higher, giving rise to the increase of stone exploitation. Due to the characteristics of different types of rock, and their advantage for construction, stone has always been the most required and used material—from the construction of communication routes to the ostentatious monuments that have been developed over the centuries. However, most of the times, quarries were established in a local exploitation perspective, since transporting stone blocks over hundreds or thousands of kilometers was very difficult to achieve [2]. From this perspective, it is possible to create a link between interconnected local geology and heritage with the identity of a region. The city of Coimbra, Portugal, is provided with several buildings in the historic center and some of them going back to the Roman occupation made with dolostone (a carbonate sedimentary rock where the dominant carbonate mineral is dolomite) and, sometimes, with dolomitic-limestone rocks [2]. Over the centuries these buildings became monuments and were the object of masonry conservation

Sustainability 2019, 11, 4158; doi:10.3390/su11154158 www.mdpi.com/journal/sustainability Sustainability 2019, 11, 4158 2 of 17 or modifications. However, from an architectural point of view, most of them preserve some or all the characteristics that marked the periods in which they were built [3]. Stone has always been used in several different ways in construction. One of the biggest uses was stonework to made ashlars when the buildings presented stone facades. However, the carbonated rocks were also calcined to produce lime, used in mortar or renders. In Coimbra, lime was of dolomitic composition, due to the presence of dolomite in the stone used for this purpose. In current residential buildings, stone blocks with smaller dimensions were used in masonry, bonded by mortar and covered with one or two layers of render and generally painted as well. In fact, stone can be one of the characteristic symbols of a region’s singularity, in terms of color and features, but also in terms of the urban landscape. Coimbra is internationally known as a city where the university presents a great preponderance after the 13th century and, since 2013, integrate the UNESCO World Heritage List with the designation “University of Coimbra—Alta and Sofia”. A tourist will generally observe the monuments from an architectural/emblematic perspective, often forgetting the history behind each block that constitutes the monuments or decorative pieces. This work highlights the use of dolostone and its influence on the building heritage in the municipality of Coimbra. The main objective is to understand the linkage of local geology with the most emblematic monuments that characterize the historical patrimony of the city and its proximity with old quarries. It is also important for the identification of locals with the exploitation potential of blocks to be used in rehabilitation and restoration.

2. Study Area

2.1. Geological Overview The municipality of Coimbra is situated in the Central region of Portugal, belonging to the Baixo Mondego sub-region, presenting an area of 319.4 km2. The old city is located in a hill with approximately 25 ha and 99 m higher altitude. Coimbra municipality is located in the contact between two major lithological groups: The Hesperic Massif with Pre-Cambrian and Paleozoic Formations, and the Meso-Cenozoic western border. The Hesperic Massif, also denominated as Iberian Massif, is mainly composed by schist and hercinic granites [4]. In Coimbra region, the schists are dominant and impose a signiﬁcant contrast in the morphology presenting higher altitudes than the sedimentary rocks. The Meso-Cenozoic western border belongs to the Lusitanian Basin [5], which is located on the Iberian Western Margin and is a non-volcanic passive margin rift [6]. The Basin occupies an area of 20,000 km2, with a length of 200 km in the NNW-SSE direction and 100 km of extension in the perpendicular direction, corresponding to 2/3 of the continental emerged area [7]. Since the 19th century, the region of Coimbra aroused the curiosity of national and foreign geologists. Over time, the records obtained from the investigations correspond to several designations for the various lithostratigraphic units. In this work, the main geological object corresponds to the Lower Jurassic dolomitic-limestone succession of Lusitanian Basin outcropping in the old urban area of Coimbra where most of the monuments can be found, commonly named with the informal designation of “Coimbra Group”. In the most recent lithostratigraphic deﬁnition of the Lower Jurassic dolomitic-limestone succession from Lusitanian Basin [8], the previous informal Coimbra Group designation [7,9,10] was abandoned and replaced by the joint of two formal units—the essentially dolomitic Coimbra Formation (Fm.), at the base, and the more calcareous and marly-limestone (when not dolomitized) S. Miguel Fm., at the top. As previously mentioned, the “Coimbra Group” was always subdivided into two diachronic units. However, according to Reference [8] with the normative imposed by the International Sustainability 2019, 11, 4158 3 of 17

Stratigraphic Guide, the transition between both is now placed at a diﬀerent level when compared to Sustainability 2019, 11, x FOR PEER REVIEW 3 of 17 previous publications. ThisThis dolomitic-limestone dolomitic-limestone succession, succession, cropping cropping out in in the the Coimbra-Penela Coimbra-Penela region, region, ranging ranging in in age age fromfrom the the Early Early Sinemurian Sinemurian to to the the Early Early Pliensbachia Pliensbachiann ([8]; ([8]; and and references references herein), herein), is is fit ﬁt between the the essentiallyessentially pelitic pelitic units units of of the the Pereiros Formation (Hetangian) and and the the marly-limestone units units of of the the Vale das Fontes Formation (Figure 1 1).). ItIt isis geographicallygeographically locatedlocated betweenbetween thethe NorthNorth ofof CoimbraCoimbra andand 2 Penela,Penela, and and occupies occupies an area of 210 km 2 withwith a a combined combined thickness thickness of of ca. ca. 110 110 m, m, presenting presenting a a W-NW W-NW orientationorientation dip, dip, with an irregular relief and tops around 300 m [[8].8].

FigureFigure 1. SyntheticSynthetic lithostratigraphic loglog forfor the the Coimbra Coimbra and and S. S. Miguel Miguel Formations Formations cropping cropping out out in thein theCoimbra-Penela Coimbra-Penela region: region: (1) Limestone; (1) Limestone; (2) dolomitc-limestone; (2) dolomitc-limestone; (3) calcareous-dolomite; (3) calcareous-dolomite; (4) dolostone; (4) dolostone;(5) impure ( dolostone5) impure (argilaceousdolostone (argilaceous/ferruginous);/ferruginous); (6) breccia ( calco-dolomitic;6) breccia calco-dolomitic; (7) dolomitic (7) sandstonedolomitic sandstone(detritial/biodetritic); (detritial/biodetritic); (8) carbonaceous (8) carbonaceous limestone; ( 9limestone;) marly limestone; (9) marly (10 limestone;) marl; (11 )( pelite10) marl;/clay; ( (1112)) pelite/clay;quartzarenite (12 (adapted) quartzarenite fromReference (adapted [from8]). Reference [8]). The Coimbra Fm. is dated from the Early to Late Sinemurian, and is on apparent continuity with The Coimbra Fm. is dated from the Early to Late Sinemurian, and is on apparent continuity with the Pereiros Fm. [11]. The upper limit of this unit corresponds to the passage between the layers of the Pereiros Fm. [11]. The upper limit of this unit corresponds to the passage between the layers of microcrystalline limestone or dolomitic limestone for the more marly-limestone layers above, deﬁned microcrystalline limestone or dolomitic limestone for the more marly-limestone layers above, defined by a discontinuity surface [8]. From bottom to top, it is possible to identify layers of massive orange by a discontinuity surface [8]. From bottom to top, it is possible to identify layers of massive orange dolomites interspersed with gray to black laminate pelitic rocks, levels of marly dolomites and low dolomites interspersed with gray to black laminate pelitic rocks, levels of marly dolomites and low fossiliferous masses presenting weak bioturbation and impure massive dolomites with a greyish fossiliferous masses presenting weak bioturbation and impure massive dolomites with a greyish color to the top. Following these are strata of dolomitic limestone and micritic dolostone with an color to the top. Following these are strata of dolomitic limestone and micritic dolostone with an orange-yellowish color, sometimes fossiliferous and bioturbated. orange-yellowish color, sometimes fossiliferous and bioturbated. In the Coimbra Fm., it is possible to recognize spathic calcite veins linked to dissolution phenomena In the Coimbra Fm., it is possible to recognize spathic calcite veins linked to dissolution with successive (or contemporaneous) recrystallization and reduced content of fossils [8]. phenomena with successive (or contemporaneous) recrystallization and reduced content of fossils [8]. The S. Miguel Fm. is dated from the Upper Sinemurian to the base of the Pliensbachian, presenting The S. Miguel Fm. is dated from the Upper Sinemurian to the base of the Pliensbachian, a thickness of 40 10 m, with more regular strata and apparent coherence when compared with the presenting a thickness± of 40 ± 10 m, with more regular strata and apparent coherence when compared Coimbra Formation. The upper limit between the S. Miguel Fm. and the Vale das Fontes Fm. represents with the Coimbra Formation. The upper limit between the S. Miguel Fm. and the Vale das Fontes Fm. the main discontinuity surface of the lithostratigraphic succession. From bottom to top, it is composed represents the main discontinuity surface of the lithostratigraphic succession. From bottom to top, it of gray and whitish dolomitic limestone, sometimes fossiliferous and bioturbated, interspersed by gray is composed of gray and whitish dolomitic limestone, sometimes fossiliferous and bioturbated, interspersed by gray or yellowish marls with little thickness (Figure 1). Finally, are identified limestones gray to orange, followed by biodetritic/fossiliferous marls and marly-limestones with a very small thickness [8]. Sustainability 2019, 11, 4158 4 of 17 or yellowish marls with little thickness (Figure1). Finally, are identiﬁed limestones gray to orange, followed by biodetritic/fossiliferous marls and marly-limestones with a very small thickness [8].

2.2. Historical Urban Development The city’s origin dates back to the Roman occupation, during Emperor Augustus domain (27 BC – AD 14). The civitas Aeminium was organized in an orthogonal configuration, in which the cardo maximus (N-S) and the decumanus maximus (E-W) intersected in the forum, which is a political, religious and mercantile center of the city [12]. One of the biggest roman remains is a cryptoportic, in the present day integrating the Machado de Castro Museum. After the Roman Empire fell off in the fifth century, Aeminium became part of the Suevian domain and with the fall of these in the sixth century, of the Visigoth domain. With the weakening of the Visigothic kingdom and coinciding with the Muslim campaigns that ran between 711 and 715, the city fell into Muslim rule in 714 and was later conquered by Christians in 1064 [13]. After the formation of the kingdom of Portugal (1139) and until 1260, the city of Coimbra was the capital of the territory. The construction of new churches and rebuilding of the old ones is related to city development. The number of constructions dated from 11–12th century is larger than the precedent and subsequent periods. At the time, the city had a military function but also corresponded to a dynamic commercial town connected with two important trade routes. Therefore, the twelfth century is considered as the golden period of the city’s history [13]. In the Middle Ages the existence of a defensive wall was fundamental for the preservation of the people and the city. The Coimbra city walls no longer exist, but they are represented in pictures, and some of the medieval defensive towers are still preserved. The construction of the Old Cathedral began in the early 1160s, and was completed in the 13th century. It was built in the same place as an existing mosque of the 9th century, due to the privileged location. The main facade presents a defensive structure, organized in a tripartite form, with central body advanced and incorporating military features, such as two towers. In the 16th century the construction of the Porta Especiosa by the architect João de Ruão using Ançã Stone [14,15], contributing to the aesthetics of the building. Despite some remodeling, its interior presents the same characteristics of its original configuration [16]. The Santa Cruz Monastery is one of the biggest constructions of the golden period. It was founded in 1131 and completed in 1228. Initially, the church was composed by one nave, reinforced by two lateral naves structured in chapels connected to the central nave and by a tower in the facade. The Santa Cruz Monastery underwent several rebuilding and modifications elaborated throughout the centuries, particularly those of the first half of the 16th century. Between 1522 and 1526, it was included the portal in Ançã Stone, created by Diogo Castilho and produced by Nicolau de Chantereine, and the cloister [17]. On the southern side of the Mondego River, Santa Clara-a-Velha Monastery started being built in 1286. The original building was supervised by the architect Domingos Domingues. The church is constituted by three naves of seven sections, without a transept and with a tripartite chapel of the polygonal apse. Floods caused by the Mondego River over the years led to several problems. Despite some restructuring, life in the monastery became unsustainable which led to its abandonment in 1677, and the nuns were installed in the Santa Clara-a-Nova Monastery, located at a higher altitude on the same side of the river [18]. The Royal Palace, with the original construction as the Alcáçova (fortified palace where the governor of the city lived during the period of Muslim rule), was built under the orders of Almançor in the late 10th century [19]. During the 20th century, archaeological excavations were carried out, which identified roman structures and mosaics stressing the importance of the local (Figure2). After the conquest of the city, the Royal Palace became the residence of Afonso Henriques (the first king of Portugal), and today is the main building of the University of Coimbra, including the S. Miguel chapel and the opulently decorated Baroque Library (1716–23) [20]. Sustainability 2019, 11, 4158 5 of 17 Sustainability 2019, 11, x FOR PEER REVIEW 5 of 17

Figure 2. Roman mosaics retrieved from the RoyalRoyal PalacePalace duringduring archaeologicalarchaeological excavations.excavations. The yellow tesserae correspond to dolostone.

With thethe permanentpermanent settlement settlement of of the the university university in Coimbrain Coimbra in 1537 in 1537 by order by order of Joã ofo III,João the III, urban the urbanspace registeredspace registered significant significant growth. growth. The construction The constr ofuction many of colleges many colleges to host studentsto host students that want that to wantbecome to become enlightened, enlightened, was one was of the one significant of the signific developmentsant developments for the city. for Onethe city. example One example is the S. Bentois the S.College, Bento locatedCollege, near located the S.near Sebasti the ãS.o Aqueduct,Sebastião Aqueduct, which was which rebuilt was in the rebuilt same in epoch, the same but maintainedepoch, but maintainedthe same layout the same of the layout previous of the one, previous that dates one, th backat dates to the back Roman to the period Roman [13 period]. The [13]. Botanic The GardenBotanic wasGarden constructed was constructed in a nearby in a nearby area of area the S. of Bento the S. CollegeBento College for educational for educat purposes.ional purposes. According According to its toimportance, its importance, the university the university was nominated was nominated to belong to tobelong the UNESCO to the UNESCO World Heritage World ListHeritage in 2013 List with in 2013the designation with the designation “University “University of Coimbra—Alta of Coimbra—Alta and Sofia”. and Sofia”. The construction of the Santa Clara-a-Nova Mo Monasterynastery began in 1649 and was completed in the 18th centurycentury withwith the the conclusion conclusion of of the the cloister, cloister, gateway gateway and and aqueduct. aqueduct. The The plant plant was was designed designed by Frei by JoFreião João Turriano Turriano and supervisedand supervised by Mateus by Mateus do Couto. do Couto. By 1696 By 1696 occurs occurs the consecration the consecration of the of church the church with withthe works the works partially partially completed, completed, but part but of thepart building of the wasbuilding already was occupied. already For occupied. the construction For the constructionof this monument, of this a monument, simplified plant a simplified and straight plant lines and werestraight used lines in accordancewere used within accordance the Mannerist with themovement. Mannerist The movement. rectangular The nave rectangular is divided nave into is five divided sections into separated five sections by framing separated Doric by pilastersframing Doricand altarpieces pilasters and of golden altarpieces carvings, of golden designed carvings, by Mateus designed do by Couto Mateus and do built Couto by and Ant óbuiltnio Gomesby António and GomesDomingos and Nunes Domingos in 1692 Nunes [21]. in 1692 [21]. In this short description,description, itit isis onlyonly mentioned mentioned few few of of the the principal principal buildings buildings referred referred below, below, due due to toits its relevance relevance in relationin relation with with the the quarries. quarries.

3. Methodology Methodology The methodology used to perform this work is expressedexpressed inin thethe flowchartflowchart ofof FigureFigure3 .3. TheThe identificationidentification of of monuments monuments was was ma madede by by bibliographic bibliographic research research and and fieldtrip fieldtrip in order in order to verify to verify the existencethe existence of dolostone of dolostone as asstonework stonework in infacades facades or or other other constructive constructive elements. The The quarries identificationidentification ofof the the non-visible non-visible was was made made using usin references,g references, consulting consulting aerial photographyaerial photography and Google and GoogleEarth Pro Earth application Pro application to verify to its verify existence, its existence, according according to the actual to the morphology actual morphology of the surface of the followed surface followedby field survey.by field survey. Alongside Alongside the field the research field resear of thech of abandoned the abandoned quarries, quarries, thedistribution the distribution of the of thelithological lithological types types was was identified, identified, and and some some characterization characterization assays assays were were carried carried out—allowing out—allowing the thefuture future to complement to complement the assessment the assessment of its of potential its potential to be usedto be inused rehabilitation in rehabilitation and restoration and restoration works. Theworks. strength, The strength, deformability deformability and durability and durability of the selectedof the selected rocks can rocks be determinatecan be determinate using several using severaltests. Density tests. Density and porosity and porosity can be obtainedcan be obtained following following EN 1936 EN (1999) 1936 [ 22(1999)] or ISRM[22] or (1981, ISRM 2007) (1981, [23 2007),24]. [23,24].Soundvelocity, Sound Schmidtvelocity, reboundSchmidt hardness, rebound slake hardness, durability slake tests durability can be performed tests can inbe accordance performed with in accordance with ISRM (1981, 2007) [23,24], uniaxial compressive strength and deformability can be carried out in line with ISRM (1981, 1999) [23,25], point load strength can be obtained following ISRM (1985) [26]. Sustainability 2019, 11, 4158 6 of 17

Sustainability 2019, 11, x FOR PEER REVIEW 6 of 17 ISRM (1981, 2007) [23,24], uniaxial compressive strength and deformability can be carried out in line with ISRMThis (1981, procedure, 1999) [in23 conjunction,25], point load with strength the use canof other be obtained characterization following methods, ISRM (1985) will [be26 important]. toolsThis to procedure, select areas in with conjunction similar rock with types, the use to th ofose other used characterization in the building methods, of monuments, will be conservation, important toolsand to restoration. select areas with similar rock types, to those used in the building of monuments, conservation, and restoration.

Figure 3. Flowchart of the methodology used.

4. Results The monuments mentioned above corresponds to some of the more relevant in the city of Coimbra. Figure 3. Flowchart of the methodology used. However, taking in consideration the presence of dolostone in monuments and urban buildings, were identiﬁed4. Results a total of 27 monuments of particular importance, which were constructed between the seventh and eighteenth centuries, proving the reputation of the dolostone during several centuries in variousThe urban monuments buildings mentioned and in other above useful corresponds or defensive to some structures of the onmore the relevant city and in surrounds the city of (FiguresCoimbra.4–6 and However, Table1). taking in consideration the presence of dolostone in monuments and urban buildings, were identified a total of 27 monuments of particular importance, which were constructed 4.1.between Location the of Ancientseventh Quarries and eighteenth centuries, proving the reputation of the dolostone during several centuriesFollowing in thevarious logic urban that the buildings ancestors and take in advantage other useful of theor localdefensive geology, structures due to logisticalon the city and and economicsurrounds aspects, (Figures research 4–6 and was Table carried 1). out in order to identify old quarries in Coimbra. Until the middle of the 20th century, some small quarries were still in progress, but nowadays no dolostone 4.1. Location of Ancient Quarries quarry is active in the surrounding area of the city. The red sandstone was also quarried and permitted to obtainFollowing blocks used the inlogic masonry. that the One ancestors of the take quarries advantage was exploited of the local in the geology, city until due 1895 to logistical when the and areaeconomic was transformed aspects, research into an arboreal was carried park out [27]. in order to identify old quarries in Coimbra. Until the middleRelated of tothe this 20th subject century, and usingsome thesmall local quarries toponymy were it canstill bein identiﬁedprogress, verybut nowadays close to the no university dolostone (Royalquarry Palace) is active a place in thatthe preservesurrounding the wordarea quarryof the (incity. Portuguese The red sandstone language: wasPedreira also) inquarried a church and (Santopermitted António to daobtain Pedreira blocks church), used in and masonry. an alley One in theof the corner quarries of the was same exploited building in (Figurethe city7 until). This 1895 quarrywhen was the active area was from transformed 13th century into to 1773an arboreal [15,28]. park [27]. Related to this subject and using the local toponymy it can be identified very close to the university (Royal Palace) a place that preserve the word quarry (in Portuguese language: Pedreira) in a church (Santo António da Pedreira church), and an alley in the corner of the same building (Figure 7). This quarry was active from 13th century to 1773 [15,28].

Table 1. Principal buildings where dolostone is observed in the city of Coimbra (adapted from Reference [29]). Sustainability 2019, 11, 4158 7 of 17

Sustainability 2019, 11, x FOR PEER REVIEW 7 of 17 Table 1. Principal buildings where dolostone is observed in the city of Coimbra (adapted from Reference [29]). Name Construction Date Conservation Works/Rebuild Name Construction Date Conservation Works/Rebuild Cryptoporticus of Aeminium 1st or 2nd century CryptoporticusS. Bartolomeu Church of Aeminium 1st 7th or century 2nd century 12th and 13th S.Almedina Bartolomeu Tower Church (city wall) 7th 9th century century 16th 12th and and 20th 13th Almedina Tower (city wall) 9th century 16th and 20th Old Cathedral 9th century several from 11th to 20th centuries Old Cathedral 9th century several from 11th to 20th centuries S. Salvador Church 11th century 12th, 16th, 17th and 18th centuries S. Salvador Church 11th century 12th, 16th, 17th and 18th centuries S.S. Jo Joãoão de de Almedina Almedina Church Church 11th 11th century century 12th, 12th, 17th 17th and and 18th 18th centuries centuries SantaSanta Justa Justa Church Church (old) (old) 11th 11th century century 16th, 16th, 18th 18th and and 20th 20th centuries centuries − S.S. Tiago Tiago Church Church 11 1112th12th century century severalseveral from from 16th 16th to to 20th 20th centuries centuries − MozarabeMozarabe Arch Arch 12th 12th century century AlmedinaAlmedina Arch Arch and and Gate Gate (city (city wall) wall) 12th 12th century century 15th, 15th, 16th, 16th, 20th 20th and and 21st 21st centuries centuries SantaSanta Cruz Cruz Monastery Monastery 12th 12th century century 15th, 15th, 16th, 16th, 17th 17th and and 19th 19th centuries centuries S.S. Miguel Miguel Chapel Chapel 12th 12th century century seve severalral from from 16th 16th to to 21st 21st centuries centuries AntoAnto Tower Tower (city (city wall) wall) 12th 12th century century 16th 16th century century ContendaContenda Tower Tower (Sub-ripas (Sub-ripas Palace) Palace) (city (city wall) wall) 12th 12th century century 16th 16th and and 20th 20th centuries centuries CelasCelas Monastery Monastery 13th 13th century century severalseveral from from 16th 16th to to 20th 20th centuries centuries Santa Clara-a-Velha Monastery 13th century several from 14th to 21st centuries Santa Clara-a-Velha Monastery 13th century several from 14th to 21st centuries S. Bento College 16th century 18th and 20th centuries S. Bento College 16th century 18th and 20th centuries S. Jerónimo College 16th century 18th, 19th and 20th centuries S.S. Sebasti Jerónimoão Aqueduct College 16th 16th century century 18th, 20th 19th and and 21st 20th centuries centuries SantoS. Sebastião António Aqueduct da Estrela Church * 16th 16th century century 20th 18th and and 21st 20th centuries centuries S.Santo Francisco António Convent da Estrela Church * 17th16th century century 18th 19th, and 20th 20th and centuries 21st centuries SantaS. Francisco Clara-a-Nova Convent Monastery 17th 17th century century 19th, several 20th from and 21st 17th centuries to 21st centuries BaroqueSanta Clara-a-Nova Library Monastery 18th 17th century century several 19th, 20thfrom and 17th 21st to 21st centuries centuries GrilosBaroque Palace Library 18th 18th century century 19th, 20th 20th century and 21st centuries SantaGrilos Clara Palace Aqueduct 18th 18th century century 20th century CatholicSanta Clara Major Aqueduct Seminary of Coimbra 18th 18th century century 19th and 20th centuries BotanicCatholic Garden Major Seminary of Coimbra 18th 18th century century 19th 19th, and 20th 20th and centuries 21st centuries Botanic Garden* Actual parish council building of Sé Nova, 18th century Santa Cruz, Almedina19th, and20th S. and Bartolomeu. 21st centuries * Actual parish council building of Sé Nova, Santa Cruz, Almedina and S. Bartolomeu.

FigureFigure 4. Principal 4. Principal monuments monuments and and buildingbuilding where dolostone dolostone was was used. used. (1) (Cryptoporticus1) Cryptoporticus of of Aeminium;Aeminium; (2) S. (2 Bartolomeu) S. Bartolomeu Church; Church; (3) Almedina (3) Almedina Tower Tower (city (city wall); wall); (4) Old (4) Cathedral;Old Cathedral; (5) S.(5 Salvador) S. Church;Salvador (6) Mozarabe Church; (6 Arch;) Mozarabe (7) Santa Arch; Justa (7) Santa Church Justa (old); Church (8) (old); S. Tiago (8) S. Church; Tiago Church; (9) Almedina (9) Almedina Arch and Arch and Gate (city wall); (10) S. João de Almedina Church; (11) Santa Cruz Monastery; (12) S. Miguel Gate (city wall); (10) S. João de Almedina Church; (11) Santa Cruz Monastery; (12) S. Miguel Chapel; (13) Chapel; (13) Anto Tower (city wall); (14) Contenda Tower (Sub-ripas Palace) (city wall); (15) Celas Anto Tower (city wall); (14) Contenda Tower (Sub-ripas Palace) (city wall); (15) Celas Monastery; (16) Monastery; (16) Santa Clara-a-Velha Monastery; (17) S. Bento College; (18) S. Sebastião Aqueduct; (19) Santa Clara-a-Velha Monastery; (17) S. Bento College; (18) S. Sebastião Aqueduct; (19) Santo António da Estrela Church; (20) S. Francisco Convent; (21) Santa Clara-a-Nova Monastery; (22) Baroque Library; (23) Grilos Palace; (24) Catholic Major Seminary of Coimbra; (25) Botanic Garden. Sustainability 2019, 11, x FOR PEER REVIEW 8 of 17 Sustainability 2019, 11, x FOR PEER REVIEW 8 of 17

Santo António da Estrela Church; (20) S. Francisco Convent; (21) Santa Clara-a-Nova Monastery; (22) SustainabilitySanto António2019, 11, 4158da Estrela Church; (20) S. Francisco Convent; (21) Santa Clara-a-Nova Monastery; (22)8 of 17 Baroque Library; (23) Grilos Palace; (24) Catholic Major Seminary of Coimbra; (25) Botanic Garden. Baroque Library; (23) Grilos Palace; (24) Catholic Major Seminary of Coimbra; (25) Botanic Garden.

Figure 5.5. Map of Coimbra at the end of thethe 12th12th century.century. It cancan bebe observedobserved mostmost ofof thethe importantimportant Figure 5. Map of Coimbra at the end of the 12th century. It can be observed most of the important buildings (legend ofof thethe samesame numbernumber asas FigureFigure4 4)) and and the the city city wall wall (adapted (adapted from from Reference Reference [ 14[14]).]). buildings (legend of the same number as Figure 4) and the city wall (adapted from Reference [14]).

Figure 6. Map of the city in the year 1834, with the indication of the existing Colleges and Convents Figure 6. Map of thethe citycity inin thethe yearyear 1834, 1834, with with the the indication indication of of the the existing existing Colleges Colleges and and Convents Convents (in (in brown, legend of the same number as Figure 4) (adapted from Reference [30]). (inbrown, brown, legend legend ofthe of the same same number number asFigure as Figure4) (adapted 4) (adapted from from Reference Reference [30]). [30]). Sustainability 2019, 11, 4158 9 of 17 Sustainability 2019, 11, x FOR PEER REVIEW 9 of 17

FigureFigure 7. 7.IllustrationIllustration of Coimbra of Coimbra made made by byPier Pier Marí Mara Baldiía Baldi in 1669 in 1669 (adapted (adapted from from Reference Reference [31]), [31 ]), wherewhere can can be beobserved observed the the area area of ofSanto Santo Antóni Antóonio da da Pedreira Pedreira qu quarryarry close close to tothe the city city wall. wall.

AlarcãoAlarc ã[2,28]o [2,28 based] based on on draws, draws, contract contract letters letters and and purchase purchase orders orders mentioned mentioned the the presence presence of of otherother quarries quarries located located inside inside the the city city walls, walls, with with the the notice notice that that thousands thousands of ofcubic cubic meters meters of ofstone stone werewere needed needed for for the the construction construction of ofseveral several major major bu buildings.ildings. Some Some of ofthe the quarries quarries were were located located very very closeclose to tothe the main main buildings buildings of ofthe the city city (Figure (Figure 8 8and and Table Table 2):2):

- - TheThe stones stones used used for building for building the Old the Cathedral Old Cathedral were extracted were extracted from thefrom construction the construction site (Figure site 9a).(Figure Some 9chapelsa). Some were chapels carved were in the carved rock in massif the rock (12th massif century) (12th [2,14,15,28]; century) [2, 14 ,15,28]; - - TheThe Montarroio Montarroio quarry quarry was was the the property property of ofSanta Santa Cruz Cruz Monastery Monastery since since the the 12th 12th century century [28]; [28 ]; - - TheThe S. Sebastião S. Sebasti ãquarryo quarry near near the the castle, castle, in inthe the place place where where after after was was constructed constructed the the College College of of ArtsArts and and very very close close to the to the aqueduct aqueduct of ofS. Sebastião S. Sebasti ã(14tho (14th century) century) [28]; [28 ]; - The Penedos Street and the Largo da Feira quarries, which disappeared with the University city’s - The Penedos Street and the Largo da Feira quarries, which disappeared with the University city’s remodeling during the second half of 20th century, located in the top of the hill, in front to the remodeling during the second half of 20th century, located in the top of the hill, in front to the New Cathedral, near the Royal Palace and several colleges [2,28] (Figure 9b). New Cathedral, near the Royal Palace and several colleges [2,28] (Figure9b). - S. Cristovão quarry, where today, the Sousa Bastos Theater is situated, close to Belcouce Tower - S. Cristovão quarry, where today, the Sousa Bastos Theater is situated, close to Belcouce Tower inside the city wall [32]. inside the city wall [32]. Outside the city walls other references mentioned the Conchada and Monte Formoso quarries, Outside the city walls other references mentioned the Conchada and Monte Formoso quarries, probably identified in outcrops still observed at the end of the 20th century [15]. probably identiﬁed in outcrops still observed at the end of the 20th century [15]. Sustainability 2019, 11, 4158 10 of 17 Sustainability 2019, 11, x FOR PEER REVIEW 10 of 17

FigureFigure 8. Location 8. Location of old of old quarries quarries in the in the geological geological ma map;p; red red dots dots correspond correspond to non-visible to non-visible quarries, quarries, blueblue dots dots correspond correspond to inactive to inactive quarries, quarries, yellow yellow dot dot correspond correspond to selected to selected quarry; quarry; (1) (1)alluvium; alluvium; (2) (2) colluvialcolluvial deposit; deposit; (3) (3) alluvial alluvial deposit lowerlower terrace; terrace; (4) (4) alluvial alluvial deposit deposit high high terrace; terrace; (5) fluvial-torrential (5) fluvial- torrentialdeposit (reddeposit sands (red of Ingote);sands (6)of conglomeratesIngote); (6) conglomerates and dark pelites; and (7) dark immature pelites; conglomeratic (7) immature sands conglomeraticwith silicified sands horizons with silicified and arcosic horizons sandstones; and arcosic (8) marly sandstones; sandstone (8) marly with fossils; sandstone (9) conglomerates,with fossils; (9)arcosarenites conglomerates, and arcosarenites pelites; (10) marlyand pelites; limestones, (10) limestonesmarly limestones, and marl; limestones (11) dolostones and marl; to dolomitc (11) dolostoneslimestones, to dolomitc pelites/clay, limestones, limestones pelites/clay, to marly limestoneslimestonesand to marly marl (a-Coimbralimestones and Formation; marl (a-Coimbra b-S. Miguel Formation;Formation); b-S. (12) Miguel gray Formation) pelites and; dolostones; (12) gray pelites (13) conglomerate, and dolostones; sandstones (13) conglomerate, and red to whitish sandstones pelites; and(14) red set to of whitish ante-mezozoic pelites; units;(14) set (I) of Fault; ante-mezozoic (II) Probable units; fault (I) and Fault;/or hide; (II) (III)Probable Normal fault fault; and/or (a) Geodesic hide; (III)vertex; Normal (b) thefault; form (a) correspondsGeodesic vertex; to Figure (b) 4the area form (adapted corresponds from Reference to Figure [9 ]).4 area (adapted from Reference [9]). On the left bank of the Mondego River, was used dolostone in both Santa Clara monasteries. In thatOn area the areleft observed bank of the six Mondego quarries, someRiver, of was them used used dolostone for lime productionin both Santa until Clara the monasteries. mid-20th century In that(Figure area are8). observed In 1889, a six book quarries, organized some by of thethem Portuguese used for lime Industrial production Association, until the aboutmid-20th the century reality of (Figurethe mines 8). In and 1889, quarries a book exploitationorganized by at the that Portuguese time, identified Industrial in the Association, urban perimeter about ofthe Coimbra reality of the thequarry mines of and Bordalo quarries (Santa exploitation Clara) and at the that extracted time, identified stone was in used the urban to the productionperimeter of of Coimbra lime, masonry the quarryand stonework.of Bordalo (Santa It is highlighted Clara) and the the resistance extracted tostone weathering was used and to the production “agreeable” of aspect lime, ofmasonry the stone andrefereeing stonework. that It wasis highlighted used in two the bridgesresistance near to weathering the city. The and other the “agreeable” quarry identified aspect isof thethe onestone the refereeingMontarroio that used was forused masonry in two and bridges lime production,near the city. but The with other less importancequarry identified at that is time the [ 33one]. the Montarroio used for masonry and lime production, but with less importance at that time [33].

Sustainability 2019, 11, x FOR PEER REVIEW 11 of 17

Table 2. List of old quarries located in Coimbra, in accordance with Figure 8 (based on field survey and [28]).

Quarry Situation 1 Conchada Abandoned/non-visible 2 Monte Formoso Abandoned/non-visible 3 S. Cristóvão Abandoned/non-visible 4 S. Sebastião Abandoned/non-visible 5 Largo da Feira Abandoned/non-visible 6 Santo António da Pedreira Abandoned/non-visible 7 Montarroio Abandoned/non-visible 8 Porta de Belcouce Abandoned/non-visible a Alto de Santa Clara Inactive/abandoned b Banhos Secos 1 Inactive/abandoned c Banhos Secos 2 Inactive/abandoned d Carvalhais Inactive/abandoned

Sustainability 2019, 11e, 4158Santa Clara-a-Nova Inactive/abandoned 11 of 17 f Bordalo Inactive/abandoned

(a) (b)

FigureFigure 9. 9.ExamplesExamples of ofoutcrops: outcrops: (a) ( aSanta) Santa Maria Maria chapel, chapel, Old Old Cathedral, Cathedral, where where the the in insitu situ stone stone can can be be observed;observed; (b ()b Outcrop) Outcrop in inCollege College of ofArts, Arts, close close to tothe the location location of ofLargoLargo da da Feira Feira quarryquarry (below (below these these locations)locations) and and S. S.Sebastião Sebastiã oquarry. quarry.

Table 2. List of old quarries located in Coimbra, in accordance with Figure8 (based on ﬁeld survey and [28]). 4.2. Dolostone Characteristics The dolostone quarriedQuarry in the layers belonging Situationto the Coimbra Fm. is characterized by heterogeneous properties,1 Conchada which provides a differential Abandoneddegradation/non-visible by its surface [34] and is much more difficult to work 2thanMonte the Formoso Ançã Stone, which is oftenAbandoned used in the/non-visible city of Coimbra for decorative 3 S. Cristóvão Abandoned/non-visible pieces, due to the white4 S. color Sebasti andão the easy cut. In monuments Abandoned dating/non-visible back to the 12th and 13th centuries, dolostone was5 Largo used da as Feira stonework on the exteriorAbandoned walls /andnon-visible also in the interior as vaults and columns. For current6 Santo buildings, António dolostone da Pedreira was adopted Abandoned in masonry/non-visible for structural purposes [35]. The chemical composition7 Montarroio of the dolostone and calcareous-dolomite Abandoned/non-visible of Coimbra Formation obtain from ashlars used8 Porta in the de Old Belcouce Cathedral presents a Abandoned content of/ non-visibleCaO of 23 to 31%, MgO from 16 a Alto de Santa Clara Inactive/abandoned to 21%, Fe2O3 vary fromb Banhos0.8 to 4% Secos and 1 residual quantities Inactive of other/abandoned oxides [15]. Analyses of dolostone from outcrops far fromc theBanhos nucleus Secos of 2 the city presents a Inactivecontent/abandoned in MgO lower than 18%, frequently d Carvalhais Inactive/abandoned e Santa Clara-a-Nova Inactive/abandoned f Bordalo Inactive/abandoned

4.2. Dolostone Characteristics The dolostone quarried in the layers belonging to the Coimbra Fm. is characterized by heterogeneous properties, which provides a diﬀerential degradation by its surface [34] and is much more diﬃcult to work than the Ançã Stone, which is often used in the city of Coimbra for decorative pieces, due to the white color and the easy cut. In monuments dating back to the 12th and 13th centuries, dolostone was used as stonework on the exterior walls and also in the interior as vaults and columns. For current buildings, dolostone was adopted in masonry for structural purposes [35]. The chemical composition of the dolostone and calcareous-dolomite of Coimbra Formation obtain from ashlars used in the Old Cathedral presents a content of CaO of 23 to 31%, MgO from 16 to 21%, Fe2O3 vary from 0.8 to 4% and residual quantities of other oxides [15]. Analyses of dolostone from outcrops far from the nucleus of the city presents a content in MgO lower than 18%, frequently between 9.5 and 15% [36]. In addition, the high content in Fe2O3 gives a yellowish color to the stone [15,36]. Sustainability 2019, 11, 4158 12 of 17

With different objectives, several drilling holes were made in the nucleus of the old town close to the location of S. Sebastião and Largo da Feira quarries. Physical and mechanical characterization aiming to define strength, deformability and durability (Table3), was carried out using 85 samples [ 37]. Dolostone with different degrees of weathering (W1, W2 and W3) was studied and classified according to its results.

Table 3. Results physical and mechanical tests (mean values) of dolostones (adapted from Reference [37]).

Vp Vs Density Porosity Is(50) UCS Ed Es Id2 1 1 3 R [m.s− ] [m.s− ] [kg.m− ] [%] [MPa] [MPa] [GPa] [GPa] [%] W1 3661 2213 2465 13.6 36.7 3.50 67.0 19.74 25.29 99.2 W2 3551 2004 2310 19.0 32.9 1.79 34.6 13.30 16.87 98.3 W3 3214 1657 1954 30.7 25.9 0.96 18.9 8.83 13.48 80.1

Where Is(50) corresponds to point load strength index corrected to a diameter of 50 mm; UCS to uniaxial compressive strength; R to Schmidt rebound hardness; Ed to Dynamic elastic moduli; Es to static elastic moduli; Id2 to slake-durability index of the second cycle; Vp and Vs to velocity of the longitudinal and transversal waves ultrasonic velocity of propagation, respectively. Tests performed with samples obtained in existing old quarries in Santa Clara area present values of density and porosity similar to the ones identified as W2 and W3 [38]. Dolostone weathering corresponds to powdering and flacking and presents differential erosion associated with the heterogeneities and the presence of recrystallized calcite filling fractures, more resistant than the dolomite [15,34]. The areas of lower quality present degrees of degradation that are more pronounced. Seco et al. [39] carried out data in outcrops of the Coimbra Formation from natural gamma-ray spectrometry measurements (total counts, K, Th and U contents). These concentrations can be used for the indirect evaluation of parameters, such as the clay minerals content, grain size variation, porosity and content of total organic carbon, among others. They observed a reduction of the gamma-ray flux from the base to the top. The dolomitic limestone and dolostone (Coimbra Fm.) varying in the base between 140 and 247 cps, in the intermediate part between 61 and 114 cps and at the top between 101 and 106 cps. Gamma-ray flux varies between 107 and 168 cps at the top of the succession (S. Miguel Fm.). In terms of mean values of the radiogenic elements, no significant differences were observed and present values of 0.4% K, 1.3 ppm U and 1.6 ppm Th.

5. Discussion and Conclusions Alarcão [2,28] highlighted the position of the quarries located in Coimbra in relation to the buildings saying they were inside the city walls and in the highest point in the city close, therefore, to the buildings to be constructed. By observing the geological map and the position of the old quarries inside the wall, it is easy to understand that most of the monuments are located inside the area where the geological units of Coimbra Formation are present (Figures4,6 and8). So the quarries located in the nucleus of the city of Coimbra provided the necessary stone for the monuments and urban buildings located in this area, while the quarries located in Santa Clara provided the needs for the buildings in the other side of the river. Only the quarries located in Santa Clara are still observed (Table2). Those located in the nucleus of the city, admitted by references in several types of documentation and bibliography, can only be assumed in areas not occupied by houses in illustrations of the time (Figure7). Two major architectural/urban phases are identiﬁed in the city of Coimbra: The period comprising the 12th and 13th centuries and later between the 16th and 18th centuries. Between the end of the 13th and 15th centuries, there is no evidence of the construction of monuments. This time period corresponds to the consolidation of the city, but also may be related to the period of the Fernandine wars (14th century), as well as to the beginning of the overseas campaigns (15th century). Sustainability 2019, 11, x FOR PEER REVIEW 13 of 17 Sustainability 2019, 11, 4158 13 of 17 period corresponds to the consolidation of the city, but also may be related to the period of the Fernandine wars (14th century), as well as to the beginning of the overseas campaigns (15th century). Dolostone was used in the stonework on the facades and structural pieces in the interior, such as Dolostone was used in the stonework on the facades and structural pieces in the interior, such vaults and columns, in the monuments constructed during the 12th and 13th centuries. In this period, as vaults and columns, in the monuments constructed during the 12th and 13th centuries. In this it was used with some frequency in decorative pieces, particularly in contrast to white painted walls period, it was used with some frequency in decorative pieces, particularly in contrast to white painted giving rise to a gilded aspect (Figure 10). Contrast was also created when, centuries later, the Ançã walls giving rise to a gilded aspect (Figure 10). Contrast was also created when, centuries later, the StoneAnçã wasStone used was due used to itsdue very to its noticeable very noticeable white colour. white colour. In some In of some these of monuments, these monuments, it is still it possible is still topossible identify to the identify geological the geological registry of registry the outcrops of the inou itstcrops interior, in its as interior, is the example as is the ofexample the Old of Cathedral the Old (FigureCathedral9a). (Figure 9a).

(a)

(b) (c)

FigureFigure 10.10. OverviewOverview ofof RoyalRoyal Palace (a) and detail of Baroque Baroque Library Library ( (bb)) and and S. S. Miguel Miguel Chapel Chapel (c (c).).

TheThe dolostone dolostone useuse inin thethe monuments,monuments, built between the 16th and and 18th 18th centuries, centuries, is is only only visible visible inin the the quoins quoins and and pilasters. pilasters. InIn thesethese buildings,buildings, dolostone was was also also applied applied in in masonry masonry on on the the outer outer walls,walls, and and lintel lintel aroundaround thethe windowswindows andand doors.doors. The gilded aspect aspect also also presents presents a a contrast contrast with with the the surroundingsurrounding white white walls.walls. TheThe dolostonedolostone belongingbelonging toto thethe CoimbraCoimbra Fm.Fm. were were studied studied throughout throughout the the years years from from a a lithostatigraphiclithostatigraphic point point of of view, view, but but onlyonly aa fewfew publications exist related related to to the the properties properties as as a a building building materialmaterial [ 15[15,34,37].,34,37]. ThisThis waswas probablyprobably due to the in inexistenceexistence of of active active quarries quarries after after the the middle middle 20th 20th centurycentury when when the the investigationinvestigation ofof thatthat mattermatter presents a great increment. The The area area of of the the last last quarries quarries ofof Bordalo Bordalo and and Montarroio,Montarroio, usedused forfor blocks and lime production production until until that that time, time, were were also also abandoned, abandoned, duedue to to the the building building boom.boom. Moreover,Moreover, thethe dolomiticdolomitic lime was replaced by calcite lime lime and and cement. cement. TheThe velocityvelocity ofof thethe longitudinallongitudinal waveswaves ultrasonic velocity of of propagation propagation for for the the W1 W1 and and W2 W2 dolostonesdolostones waswas consideredconsidered asas mediummedium andand lowlow forfor thethe W3W3 dolostones.dolostones. According According to to the the uniaxial uniaxial compressivecompressive strengthstrength and the the point point load load strength strength in indexdex corrected corrected to a to diameter a diameter of 50 of mm 50 mmvalues, values, the therock rock strength strength was was classified classified as high as highfor the for W1 the gr W1oup, group, medium medium for W2 forand W2 low and for W3. low The for W3.porosity The porosityvalues of values the W1, of the W2 W1, and W2 W3 and dolostones W3 dolostones presented presented a medium, a medium, high high and and very very high high porosity, porosity, Sustainability 2019, 11, 4158 14 of 17 Sustainability 2019, 11, x FOR PEER REVIEW 14 of 17 respectively. So, it is acceptedaccepted that thethe dolostonedolostone present mechanical properties that allow over the centuries its utilization in construction, asas cancan bebe observed.observed. As presented in Table2 2,, allall thethe buildingsbuildings presentpresent acrossacross thethe centuriescenturies severalseveral modifications,modifications, reorganizations and changeschanges ofof use.use. At At the the en endd of of 19th 19th century, century, the Old Cathedral was in conservationconservation/restoration/rehabilitation/restoration/rehabilitation works for tenten years [[14].14]. The The Colleges Colleges that belong to the University campus, the Baroque Library, S. MiguelMiguel Chapel, Botanic Garden and others had also restoration andand rehabilitationrehabilitation worksworks [[40]40]. In preservationpreservation and and rehabilitation rehabilitation of of old old buildings buildings the usethe ofuse new of stonesnew stones is often is neededoften needed to replace to thereplace degraded the degraded ones, which ones, do which not present do not safe present conditions. safe conditions. The exploitation The exploitation of dolostone of around dolostone the cityaround of Coimbra the city hasof Coimbra been abandoned has been for abandoned more than for twenty more years.than twenty This conducted years. This to theconducted use of similar to the stonesuse of similar from other stones parts from of theother country parts of when the country the replacement when the is replacement need. is need. An example of this is the S. Francisco Convent. It corresponds to a large compound of different different built bodies, with two to three floorsfloors each, organized around a cloister. Built in the 17th century, the structure was occupied by the Franciscans until 1843, after which, and and until until the the mid-20th mid-20th century, century, several factories were installed, such as a wool factory from 1888 until 1980, with considerable impact on the main structure [[41].41]. The rock used in thethe facades and pavement of thethe rehabilitationrehabilitation works (2010–2016)(2010–2016) waswas aa dolomitic breccia thatthat came from Serra de Aires and Candeeiros,, near Moleana, Porto de MMós.ós. Considering that most of the old buildings of Coimbra are included in the UNESCO World Heritage List,List, it it is is important important to preserveto preserve the the heritage heritage and theand materiality the materiality of the city.of the Taking city. intoTaking account into theaccount existence the existence of several of outcropsseveral outcrops in the Santa in the Clara Santa region Clara region that corresponds that corresponds to old to quarries, old quarries, some ofsome them of exploitedthem exploited up to up the to last the twenty last twenty years years for the for production the production of aggregates; of aggregates; it is possibleit is possible to use, to withuse, with prudence prudence and and vigilance vigilance from from the authorities,the authorities, stone stone from from those those quarries. quarries. The The one one presented presented in Figurein Figure 11, 11, corresponds corresponds to the to indicatedthe indicated as d as(yellow d (yellow dot) ondot) Figure on Figure8, due 8, to due the easyto the access easy toaccess trucks to andtrucks to theandoccurrence to the occurrence of stone of with stone good with quality good hasquality great has relevance great relevance for this use. for this The use. other The quarries other signalizedquarries signalized in Figure 6in also Figure present 6 also proper present stone, proper but duestone, to but the locationdue to the near location houses near or monastery houses or (Santamonastery Clara-a-Nova (Santa Clara-a-Nova Monastery) andMonastery) with diffi andcult with accessibility, difficult areaccessibility, less recommended are less recommended for this use. for this use.

Figure 11. ExampleExample of an an old old quarry quarry that that allows allows the the exploi exploitationtation of of blocks blocks for for conservation, conservation, restoration and rehabilitation of monumentsmonuments (40(40°10◦100′54.4″00 NN 8°26 8◦26′37.3037.3″00 W).W). Sustainability 2019, 11, 4158 15 of 17

The “identity” of the city is dependent on its geological location, and the stone corresponds to a symbol that characterizes its gilded aspect. This was highlighted by Vasconcelos in 1930 [14] in relation to the apse of the chapel in Old Cathedral, and can be extended to the chromatic characteristics of the stone buildings and the city.

Author Contributions: All authors contributed equally to this paper and approved the final manuscript. Conceptualization and methodology, F.P.F., J.D., P.A. and L.C.; field work, J.D., F.P.F., R.F. and L.C.; laboratory tests, investigation and validation data, P.A., L.C. and R.F. All authors were involved for the writing and editing of the manuscript. Funding: This research received no external funding. Acknowledgments: The financial support of FCT-MEC through national funds and, when applicable, co-financed by FEDER in the ambit of the partnership PT2020, through the research project UID/Multi/00073/2013 of the Geosciences Center is acknowledged. Conflicts of Interest: The authors declare no conflict of interest.

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