Siderite Cinnabar Sphalerite

**Chemical composition:** FeCO₃

**Hardness:** 3.8‒4.3

**Density:** 3.7‒3.9 g/cm³

**Crystal symmetry:** Trigonal

**Luster:** Vitreous to Pearly

**Info:** Siderite is a valuable iron mineral with a variable colour from yellow to dark brown or black. Siderite is commonly found in hydrothermal veins associated with barite, fluorite, galena, and others. It is also a common diagenetic mineral in sedimentary rocks (e.g., sandstones), where it sometimes forms concretions.

**Cinnabar (HgS)** is the most common ore of mercury (quicksilver) and is the historic source for the brilliant red pigment (vermilion). This mineral is very often associated with pyrite, marcasite, opal, quartz, calcite and barite.

**Sphalerite (zinc blende, ZnS) ** is the most important ore of zinc. It is usually associated with galena, pyrite, chalcopyrite, calcite, dolomite and fluorite.