Struvite

Struvite
Crystals of struvite from dog urine
General
CategoryPhosphate mineral
Formula
(repeating unit)
NH4MgPO4·6H2O
IMA symbolSuv[1]
Strunz classification8.CH.40
Crystal systemOrthorhombic
Crystal classPyramidal (mm2)
H-M symbol: (mm2)
Space groupPmn21
Identification
ColorColorless, white (dehydrated), yellow or brownish, light gray
Crystal habitEuhedral to platy
TwinningOn {001}
Cleavage{100} perfect
FractureUneven
Mohs scale hardness1.5–2
LusterVitreous to dull
StreakWhite
DiaphaneityTransparent to translucent
Specific gravity1.7
Optical propertiesBiaxial (+) 2V Measured: 37°
Refractive indexnα = 1.495 nβ = 1.496 nγ = 1.504
Birefringenceδ = 0.009
SolubilitySlightly soluble, dehydrates in dry, warm air
Other characteristicsPyroelectric 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.

  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ "Struvite" (PDF). Handbook of mineralogy.
  3. ^ "Struvite Mineral Data". Webmineral.
  4. ^ "Struvite". Mindat.