La utilización de rocas vaugneríticas en los monumentos de Salamanca

Resum

Many Renaissance and Baroque monuments of the city of Salamanca ("Mankind Heritage") were built between the sixteenth and nineteenth centuries using vaugneritic stone. Recognition of the stone itself in monuments together with historic documentation led to two quarries to be proposed as the original sites of provenance. One of them might be located close to the village of La Magdalena, about 70 km south of the city of Salamanca, close to the locality of Barco de Avila, in the Spanish Central System; the rocks from this quarry being Variscan coarse-grained diorites and quartzdiorites. The second quarry is located at Calzadilla del Campo, close to Ledesma, 34 km west of Salamanca. The rocks from this quarry include Variscan monzo-diorites and quartz-monzodiorites showing a conspicuous vaugneritic texture consisting of large decussate biotite and amphibole crystals. For this latter quarry, an almost continuous production during a time-span of 300 years has been inferred, although the varying rhythms of production appear to have depended on historic, economic and social circumstances. An initial period of prosperity can be dated to the end of the sixteenth century and the beginning of the seventeenth century, while a second one seems to have developed during the second half of the eighteenth century as can be deduced not only from certain relevant monuments to be found in the city of Salamanca but also from many ancestral homes from the town of Ledesma made of vaugneritic stones. The weathering of the typical sandstone ("golden stone") from Salamanca used close to the base of the monuments seems to have been an increasingly important problem in construction in medieval times. This problem was partially solved using Cainozoic microconglomerate and mainly by the use of vaugneritic stones and other plutonic rocks (granitoids), which also were used to definitively reinforce the Roman Bridge and the Cathedrals. The vaugnerite stone also provided an interesting chromatic effect on some Baroque monuments, such as that of La Clerecía, resulting in a good combination of black vaugneritic stones and white or golden Cainozoic sandstones. Finally, the presence of many shields, lintels and monolithic shafts made of vaugneritic stone underscores its versatility and a appropriateness for sculpture work. Technical tests applied to the stone of the monuments and to the stone from the quarries are currently in progress with a view to completing the necessary groundwork for future restorations.