The Mineral, Limonite is a Iron Ore mineral and accounts for a small percentage of the iron mined. Limonite is crystaline to amorphous, has a hardness of 1 to 5.5, SG of 3.4 to 4, and is yellowish, brown or black. Limonite is the result of decomposition of iron minerals, where water, carbon dioxide, humus acid and oxygen react with the minerals and gradually transform them into limonite. It is very common, and can be found with other iron minerals such as pyrite, hematite, etc.. In addition to a source for iron, limonite is used as paint pigment and in some ceramics (for color)