THE USE OF SOAPSTONE IN MASTERPIECES IN THE STATE OF MINAS GERAIS

Abstract

The region of the State of Minas Gerais known as iron-bearing, which includes the cities of Ouro Preto, Congonhas do Campo, Mariana and Sao Joao del Rei, has the greatest number of masterpieces made· in soapstone in Brazil. They were all made around the same time, the second half of the eighteenth century, during the baroque-rococo transition in the colonial period The abundance of soapstone, its softness and the facility to cut it into large pieces made possible its use in sculptures, ornaments and the facades of churches' and,' at the other extreme, in the manufacture of cooking utensils. Among the masterpieces made with soapstone in Brazil must be noted the works of Antonio Francisco Lisboa, known as Aleijadinho. These include the Twelve Prophets in Congonhas do Campo; the ornaments of the Sao Francisco de Assis church in Ouro Preto; the facades of the Sao Francisco de Assi~ and Nossa Senhora do Carmo churches, both in Sao Joao del Rei, and the image called 'Cristo da Smaritana' in Mariana. Although these masterpieces were done more or less at the same time they now show different states of preservation and natural degradation. For example the Prophets show several signs· of damage such as broken fingers, and unsuitable materials used to join separated pieces (such as cement and adhesives) are, different from' the original colour as we can see, for example in the base of the Prophet Osea. Furthermore the,re are signs of interventions as in the Arabic 'inscription, for example, at· the back of the Prophet Amos ~ Some of the Prophets,· such as Abdias, show· natural degradation of the stone visible as holes of various sizes. Also, the facade of the Born Jesus de Matozinhos church shows fissures and treatments with different materials. The facade of the Sao' Francisco de Assis church in Ouro Preto shows damage such as broken pieces of the figures: the left side angel's leg and the ornament over the door at the right side. In the same monument \Ve can also see different stages of degradation. The facades of the churches of Sao Francisco de Assis and Nossa Senhora do Carmo, , both in Sao Joao'del Rei, show damage such as' spalling of the soapstone. Only the facades of Sao Francisco de Assis and Nossa Senhora do Carmo in Mariana are in generally:good condition. Tests done with several pieces from different sources of soapstone show different amounts of aluminium oxide (AI203) and iron oxide (Fe203)' An·assay done by the Historic' Heritage Service in 1941 noted the presence of elevated amounts of iron oxide in the decomposing soapstone. Recent experiments on accelerated decomposition confirm the presence of iron oxide in cavities/holes in the stone caused by dissolution of sulphate and carbonate~~they also confirm the relationship between the decomposition of soapstone and the elements and show the contrast between healthy stone before use and the current state which can be seen on the facade of Sao Francisco de Assis in Duro Preto and in the Prophets. The results of current experiments show that the variation in the state of preservation of the stone is due to the mineralogical composition and the initial decomposition of the stone combined with the action of time. It was not possible to prove that the action of environmental pollution was responsible for the degradation of these monuments. And alth~ugh' it is known that the decay of soapstone is due to natural factors, there is no informationthat can help us stop or at least minimize the natural degradation process. While tests are being done regarding the protection of these monuments of great historic and artistic value, it is urgent and necessary to protect t~em against physical attack which has already caused· damage~ , Authors' address: CECOR EBA-UFMG, 'Av. Antonio Carlos 6627, 31.270 Belo Horizonte MG,' Brazil.