<P> A mineral is a naturally occurring chemical compound, usually of crystalline form and abiogenic in origin (not produced by life processes). A mineral has one specific chemical composition, whereas a rock can be an aggregate of different minerals or mineraloids . The study of minerals is called mineralogy . </P> <P> There are over 5,300 known mineral species; as of March 2017, over 5,230 of these had been approved by the International Mineralogical Association (IMA). The silicate minerals compose over 90% of the Earth's crust . Silicon and oxygen constitute approximately 75% of the Earth's crust, which translates directly into the predominance of silicate minerals . </P> <P> Minerals are distinguished by various chemical and physical properties . Differences in chemical composition and crystal structure distinguish the various species, which were determined by the mineral's geological environment when formed . Changes in the temperature, pressure, or bulk composition of a rock mass cause changes in its minerals . </P>

Where do most useful minerals occur in nature