Struvite
| Struvite | |
|---|---|
Crystals of struvite from dog urine
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| General | |
| Category | Phosphate mineral |
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Formula (repeating unit) |
NH4MgPO4·6H2O |
| 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 platey |
| 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 (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 platey 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.
Struvite was first described from medieval sewer systems in Hamburg Germany in 1845 and named for geographer and geologist Heinrich Christian Gottfried von Struve (1772–1851).
Struvite is occasionally found in canned seafood, where its appearance is that of small glass slivers, objectionable to consumers for aesthetic reasons but of no health consequence.
Use of struvite as an agricultural fertilizer was in fact first described in 1857.
Struvite precipitates in alkaline urine, forming stones. Struvite is the most common mineral found in urinary tract stones in dogs, and is found also in urinary tract stones of cats and humans. Struvite stones are potentiated by bacterial infection that hydrolyzes urea to ammonium and raises urine pH to neutral or alkaline values. Urea-splitting organisms include Proteus, Pseudomonas, Klebsiella, Staphylococcus, and Mycoplasma.
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Wikipedia