Struvite (magnesium ammonium phosphate) is a phosphate mineral with formula: NH4MgPO4·6H2O. Struvite crystallizes in the orthorhombic system as white to yellowish or brownish-white pyramidal crystals or in platy mica-like forms. It is a soft mineral with Mohs hardness of 1.5 to 2 and has a low specific gravity of 1.7. It is sparingly soluble in neutral and alkaline conditions, but readily soluble in acid.
Crystals of struvite from dog urine
Dog struvite bladder stones
Struvite. Clogged sewer pipes
Phosphate minerals contain the tetrahedrally coordinated phosphate (PO43−) anion, sometimes with arsenate (AsO43−) and vanadate (VO43−) substitutions, along with chloride (Cl−), fluoride (F−), and hydroxide (OH−) anions, that also fit into the crystal structure.
Apatite
Thin section of apatite-rich carbonate in cross polarized transmitted light.