Facoidal Gneiss

Brazil

Central Bank of Brasil (1908)

Year designation

2024

Lithology

Garnet-bearing biotite-quartz-feldspar gneiss

Aesthetics

Pinkish-grey with characteristic large k-feldspar crystals looking like eyes

Geological settings

Neoproterozoic – Edicarian – Rio de Janeiro Suite

Location

Rio de Janeiro and Niterói, Rio de Janeiro, Brazil

Central Bank of Brasil (1908)

The most carioca of rocks

Facoidal Gneiss is the most ‘carioca‘ (relative to the city of Rio de Janeiro) of rocks; the most representative lithology of Rio’s natural and built heritage. Due to its abundance on the rocky outcrops around Guanabara Bay, it was exploited in many quarries and continuously used to build Rio’s World Heritage site from the Portuguese occupation (16th century) to the mid-20th century. There are countless examples of its use as rough or finely worked building stone in Rio, such as the remarkable baroque art of Master Valentim or many eclectic heritage buildings (e.g. the National Historical and Artistic Heritage Agency Building). This stone was also used in the ’Valongo Wharf ‘and ‘Burle Marx’s House’ (UNESCO World Heritage Sites) and some other Brazilian cities. Its geological history and features shaped the famous landscape of Guanabara Bay, including the IUGS Geosite of Sugar Loaf.

18th-century bridge at one of the Copacabana access road

Church of Our Lady of the Candelaria

Nuria Fernández Castro. 

Centro de Tecnologia Mineral – CETEM, Av. Pedro Calmon, 900, Cidade Universitária, 21941-908 Rio de Janeiro – RJ, Brasil

nutriacastro@gmail.com