Cerusite mineral sample. This mineral is a form of lead carbonate, and is here present as clear or white crystals embedded in a matrix of galenite (grey). Cerusite is an orthorhombic mineral, and is also known as white lead ore. Galenite, which is lead sulfide, is also an ore used as a source of lead. This sample is from Zellerfeld in Germany's Harz region. A pencil tip (right) is shown for scale.