what are minerals and how they are formed
A mineral is a naturally occurring substance, representable by a chemical formula, that is usually solid and inorganic, and has a crystal structure.It is different from a rock, which can be an aggregate of minerals or non-minerals and does not have a specific chemical composition.ocks like limestone or quartzite are composed primarily of one mineralâ calcite or aragonite in the case of limestone, and quartz in the latter case. Other rocks can be defined by relative abundances of key (essential) minerals; a granite is defined by proportions of quartz, alkali feldspar, and plagioclase feldspar.