Minium (mineral) Minium (mineral) Minium is the naturally occurring form of lead tetroxide, PbPbO also known as red lead. Minium is a light-to-vivid red and may have brown-to-yellow tints. It typically occurs in scaly-to-earthy masses. It crystallizes in the tetragonal crystal system. Minium is rare and occurs in lead-mineral deposits that have been subjected to severe oxidizing conditions. It also occurs as a result of mine fires. It is associated with cerussite, galena, litharge, massicot, mimetite, native lead, and wulfenite. It occurs in relatively small amounts throughout the world: Langhecke, Hesse; Badenweiler, Baden-Württemberg; Bleialf, Eifel district; Horhausen (), Rhineland-Palatinate in Germany. It
Mineral ore of zinc, or cassiterite (SnO), an ore of tin. Gems are minerals with an ornamental value, and are distinguished from non-gems by their beauty, durability, and usually, rarity. There are about 20 mineral species that qualify as gem minerals, which constitute about 35 of the most common gemstones. Gem minerals are often present in several varieties, and so one mineral can account for several different gemstones; for example, ruby and sapphire are both corundum, AlO. Minerals are classified by variety, species, series and group, in order of increasing generality. The basic level of definition is that of mineral species,