Gold was abundant in the city of Cuiabá and was the starting point for is emergence and development. Bandeirantes (explorers/fortune hunters during the colonial period), mostly coming from São Paulo, made their expeditions into inland Brazil firstly to capture and enslave natives and, in this process, discovered important alluvial deposits associated with the rivers in the region. Today, this precious metal is still present and being prospected in the Baixada Cuiabana region, and is found preserved (impregnated and visible) in the plaster of the walls of the Church of Nossa Senhora do Rosário e São Benedito, for example. Many buildings in the central areas were built and adorned with ex situ geological material such as ironstone and blocks of milky quartz, and some of these buildings are identified in this work as an example of the use of geodiversity as a constructive and historical element. Ironstone is described as a solid, reddish sedimentary rock resulting from a chemical alteration process (lateritization), and the quartz blocks come from gold veins that cut the rocks of the Cuiabá Group, in the Baixada Cuiabana region. In addition to these materials that are present in some locations and represent geodiversity elements, an in situ example of geodiversity is described. It is an exposed geological fault that stands out in the landscape, located in an aligned hill where historic constructions were built. Because it is of unique geoscientific interest and preserved within the central urban boundary of the city of Cuiabá, this place can be considered the first geosite, which is described in the present work
