Hematite

specimen number:
2292388

location:
Ouro Preto, Minas Gerais, Brazil

description:
A classic bright metallic hematite rosette of crystals. Slight micro-damage present. Complete all around.

Ouro Preto, located in the mountainous region of Minas Gerais, Brazil, is situated within the eastern portion of the Quadrilatero Ferrifero (Iron Quadrangle). Geologically, the area is characterized by the Minas Supergroup, which contains major metasedimentary rock formations, most notably the Caue Itabirite--a banded iron formation composed of alternating layers of iron oxides and quartz. During tectonic deformation around 500 million years ago, hydrothermal fluids deposited gold along shear zones and in quartz-carbonate veins cutting through these rocks. Historically, the city was founded as Vila Rica in 1711 after explorers discovered alluvial gold with a distinctive dark coating of iron oxide, earning it the name Ouro Preto (Black Gold). This discovery triggered one of the world's earliest major gold rushes, attracting tens of thousands of Portuguese settlers and enslaved African laborers who carved out extensive underground mines. While the gold deposits were largely exhausted by the mid-nineteenth century, the town's mineral legacy survived, and the surrounding district remains a globally recognized source of iron ore, imperial topaz, and other gemstones.

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