The Witwatersrand area of South Africa produces a significant percentage of the world's gold. This is a spectacular sample of Precambrian high-grade gold ore from South Africa’s Blyvooruitzicht Gold Mine. The rock is from the Carbon Leader (also known as the Carbon Leader Reef & Carbon Leader Seam), a blackened, hydrocarbon-rich stromatolitic interval richly impregnated with native gold (Au) and radioactive uraninite/pitchblende (UO2). This is a paleoplacer deposit, part of an ancient alluvial fan succession.
Stratigraphy & Age: Carbon Leader Member, Main Conglomerate, lower Johannesburg Subgroup, lower Central Rand Group, Witwatersrand Supergroup, lower Neoarchean, ~2.9 billion years old.