[Chemical composition] Ca in the composition can be replaced by rare earth elements (mainly Ce) and trace elements Sr as incomplete isomorphisms. The rare earth content is generally not more than 5%. According to different additional anions, apatite divided into the following sub-types: Fluorate fluorapatite Ca 5 [PO 4 ] 3 F Chlorapatite Ca 5 [PO 4 ] 3 Cl Hydroxyapatite Ca 5 [PO 4 ] 3 (OH) Carbon apatite (Carbonate-apatite) Ca 5 [PO 4 ,CO 3 (OH)] 3 (F, OH) Among them, fluoroapatite is the most common, which is generally referred to as apatite. Carbonapatite has the remaining negative charge due to [CO 3 ] 2-  instead of [PO 4 ] 3- , for which reason [CO 3 ] 2- is combined with (OH) - or F - The ion cluster form enters the crystal lattice, however, when one [CO 3 ] 2- replaces one [PO 4 ] 3- , only 0 4 [CO 3 ] 2- combines with (OH) - or F - , so Ca 2+ can be replaced by K + , Na+, etc. to achieve electricity price balance. [Crystal structure] hexagonal crystal system; Figure H-21 Apatite crystal [Physical properties] No impurities are colorless and transparent, but often light green, yellowish green, brown red, light purple. The apatite formed in the sedimentary rock is dyed dark gray to black due to the organic matter; the glass is shiny, and the fracture is fat. luster. The cleavage {0001} is not developed; the fracture is not flat. Hardness 5. The relative density is 3.18~3.21. Phosphorescence often occurs after heating. Crisp. [genesis and occurrence] In the sedimentary rocks, sedimentary metamorphic rocks and alkaline rocks, huge industrially valuable deposits can be formed. It is a secondary mineral in various magmatic rocks and granitic pegmatites. The phosphate rock formed by biochemical action is mainly formed by the accumulation of bird droppings or animal bones. It is mainly composed of hydroxyapatite. For example, in the Xisha Islands of China, the phosphate rock formed by bird droppings can be as thick as 2 m. In addition, human gallstones and urinary tract stones may contain small amounts of carbon apatite and hydroxyapatite. [Identification Features] When the crystal is large, crystal form, color, gloss, and hardness can be used as identification features. If the need to rely on finely dispersed state chemical identification: molybdenum powder is placed on the amine mineral acid, nitric acid plus one drop, generating a yellow precipitate phosphorus ammonium molybdate, this test method is effective phosphorus (Note: When carbonates and Organic matter often appears in blue precipitates). SS Powder,316L Powder,Steel Powder,Stainless Steel Powder Luoyang Golden Egret Geotools Co., Ltd , https://www.hvofpowders.com
a 0 = 0.943 to 0.938 nm, c 0 = 0.668 to 0.686 nm; Z = 2.
[Form] It is often columnar, short columnar, thick plate or plate crystal (Figure H-21). The aggregate is granular and dense.
Apatite
Ca 5 [PO 4 ] 3 (F, OH)