Beige Bahia, the Brazilian travertine-like limestone

The “Beige Bahia” is a unique light beige limestone visually resembling a travertine. It is an uncommon type of natural stone and a vital mineral resource of Ourolândia (State of Bahia), a municipality in the Northeast region of Brazil, where around 25 quarries and 45 looms in several processing plants are reported (Iza et al. 2022).Member of the Caatinga Formation, Miocene-Pleistocene age, it is, in fact, a secondary, calcrete type, limestone formed by chemical, physical and biogenic alteration of a marine Neoproterozoic limestone of the Salitre Formation. It resembles a brecciated limestone and is characterized by a heterogeneous arrangement of calcareous fragments in a micritic matrix.The presence of irregular and centimetric cavities is typical, resulting from the dissolution and recrystallization processes. Most of them seem like geodes due to calcite crystals covering their walls. Another relevant characteristic is the sparse occurrence of whitish areas, composed of microcrystalline calcite and minor clay minerals (illite group).Beige Bahia had its exploration and processing started in the 1960s, although it had already been “discovered in the backlands of Bahia in the 1950s” when the pioneering producers called it “Marta Rocha marble”, in allusion to the famous Miss Brazil 1956 from Bahia, and the stone had immediate acceptance in the yet incipient Brazilian market of marbles and granites (Ribeiro et al. 2002)Primarily named “Beige Bahia”, it has been commercialized as a travertine to which it does indeed have some similar characteristics and is even called “National Travertine” or “Brazilian Travertine”. Resembling imported travertines, but at a much lower price, this stone is one of the most commercialized all over the country, and exported mainly to USA, for covering floors and walls, indoors (mainly) and outdoors. It is also commonly used on kitchen, bathroom sink tops and other furniture.Beige Bahia can be found in countless residential and in façades and columns of modern buildings. It is also covering important Brazilian heritage buildings, such as the Planalto Palace and the Federal Supreme Court, in Brasília (the capital of Brazil) (Frascá et al. 2020). In Rio de Janeiro, the heritage building of the Bank of Brazil Cultural Centre has Beige Bahia flooring in the exposition room. Another example is the Beige Bahia veneers at the Legislative Assembly of Minas Gerais building.All aspects mentioned here demonstrate the geological, historical, and social importance of this rock, whose occurrence must be known and publicized.ReferencesFrascá, M.H.B.O., Neves, R., Castro, N.F. 2020. The White Marbles of Brasília, a World Heritage site and capital of Brazil. London, Geological Society Special Publications, 486: 217-227. https://doi.org/10.1144/SP486-2018-31.Ribeiro, A.F., Pereira, C.P., Braz, E., Magalhães, A.C.F., Chiodi Filho, C. 2002. Mármore Bege Bahia em Ourolândia-Mirangaba-Jacobina, Bahia: geologia, potencialidade e desenvolvimento integrado. Salvador, CBPM. (Série Arquivos Abertos; 17). 56p.Iza, E.R.H.F (org.). 2022. Rochas ornamentais do estado da Bahia. 2nd ed. Salvador, CPRM. https://rigeo.cprm.gov.br/bitstream/doc/21244/1/irm_rochas_ornamentais_ba.pdf, accessed on 5 Jan. 2023.