Struvite
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 | |
|---|---|
Crystals of struvite from dog urine | |
| General | |
| Category | Phosphate mineral |
| Formula (repeating unit) | NH4MgPO4·6H2O |
| IMA symbol | Suv |
| 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 | |
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.
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