Struvite

Struvite
Crystals of struvite from dog urine
General
Category	Phosphate mineral
Formula (repeating unit)	NH4MgPO4·6H2O
IMA symbol	Suv[1]
Strunz classification	8.CH.40
Crystal system	Orthorhombic
Crystal class	Pyramidal (mm2) H-M symbol: (mm2)
Space group	Pmn21
Identification
Color	Colorless, white (dehydrated), yellow or brownish, light gray
Crystal habit	Euhedral to platy
Twinning	On {001}
Cleavage	{100} perfect
Fracture	Uneven
Mohs scale hardness	1.5–2
Luster	Vitreous to dull
Streak	White
Diaphaneity	Transparent to translucent
Specific gravity	1.7
Optical properties	Biaxial (+) 2V Measured: 37°
Refractive index	nα = 1.495 nβ = 1.496 nγ = 1.504
Birefringence	δ = 0.009
Solubility	Slightly soluble, dehydrates in dry, warm air
Other characteristics	Pyroelectric and piezoelectric
References	[2][3][4]

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.

Struvite urinary stones and crystals form readily in the urine of animals and humans that are infected with ammonia-producing organisms. They are potentiated by alkaline urine and high magnesium excretion (high magnesium/plant-based diets). They also are potentiated by a specific urinary protein in domestic cats.