This is a group of phosphate minerals with similar chemical compositions as well as physical properties. A natural calcium phosphate, usually containing fluorine and appears in the earth's crust as an important constituent of phosphorite or phosphate rock. Apatite is normally formed under a wide variety of conditions, either found in igneous, metamorphic and sedimentary rocks or as crystals found in granite. Also a chief component of the bony structure of teeth. Some apatite can also be found to contain significant amount of rare-earth elements and can be used as an ore for those metals. However, apatite often contains uranium and hence displays radioactive aspects. Uses: as a source of phosphorus and phosphoric acid, manufacture of fertilisers ( apatite concentrate is the main raw material in phosphate fertilisers) laser crystals and gemstones. Colours : yellow, brown, blue, purple, pink or colourless. Because of the colours, it is often frequently cut as a gemstone.
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