English: Sulfidic Chromitite from South Africa. This rock sample is 45 millimetres across at its widest. It is of mid-Paleoproterozoic age, about 2054-2055 million years old. This rock comes from Level 17 of the Rustenburg platinum mine, northwest of Johannesburg, South Africa. Stratigraphically, the sample comes from the Merensky Reef, uppermost Critical Zone, Rustenburg Layered Suite of the Bushveld Complex, a large layered igneous intrusion, which contains about 75-80% of all the world’s chromium reserves. The chromium is mined from chromitite (chromite-dominated intrusive igneous rock). All the black crystals in this rock are chromite (FeCr2O4). This chromitite also has scattered sulfides (small, metallic-lustered, brassy gold-colored masses) that are non-platiniferous. Scattered dark-colored orthopyroxene and grayish-colored plagioclase feldspar are also present.