Brushite is a mineral with the chemical formula CaHPO4ยท2H2O. It is believed to be a precursor of apatite and is found in guano-rich caves, formed by the interaction of guano with calcite and clay at a low pH. Brushite was first described in 1865 and named for the American mineralogist George Jarvis Brush (1831-1912). It forms crystals of prismatic shape having a monoclinic crystal structure.[1]
Brushite is the original precipitating material in calcium phosphate kidney stones.