Hazenite

Hazenite is a hydrous phosphate mineral with chemical formula of KNaMg₂(PO₄)₂ · 14 H₂O, therefore a hydrous alkali magnesium phosphate. It is a member of the struvite group.^[4]

Hazenite
General
Category	Phosphate mineral Struvite group
Formula	KNaMg2(PO4)2 · 14 H2O
IMA symbol	Hz[1]
Strunz classification	8.CH.40
Dana classification	40.01.01.03
Crystal system	Orthorhombic
Crystal class	Dipyramidal (mmm) H–M Symbol: (2/m 2/m 2/m)
Space group	Pmnb
Unit cell	a = 6.9349, b = 25.1737 c = 11.2189 [Å]; Z = 4
Identification
Formula mass	276.331 g/mol
Color	Colorless
Crystal habit	Radiating elongated tabular or prismatic clusters or single bladed tabular crystals
Cleavage	{001} Good
Tenacity	Brittle
Mohs scale hardness	2 – 2.5
Luster	Vitreous
Streak	White
Diaphaneity	Transparent
Specific gravity	1.91
Optical properties	Biaxial (+)
Refractive index	nα =1.494(1), nβ = 1.498(1), nγ = 1.503(1)
2V angle	41°
Dispersion	Strong r < v
Solubility	In water
References	[2][3][4]

It was first described for an occurrence adjacent to Mono Lake, California, and named after Robert M. Hazen of the Carnegie Institute.^[5] It was approved as a new mineral on February 28, 2008 by the Commission on New Minerals of the International Mineralogical Association.

It occurs as crystal clusters associated with decomposed cyanobacteria remnants on calcite or aragonite.^[4] It is precipitated by microbes when the lake has been dry for so long that phosphorus levels build up, poisoning the microbes. They dispose of the excess phosphorus by excreting hazenite crystals.^[6] The crystals disappear when it rains or the lake level rises.^[7]