Hematite

Fe₂O₃

Hematite is usually found as a weathering product of iron-bearing minerals, but occurs in sediments and their metamorphosed equivalents. The red coloration in many sedimentary rocks is due to the presence of hematite. Hematite may be silver/gray or red — the silver form with a metallic luster is known as "specular hematite". Hematite has a distinctive red streak.