Laurionite

Laurionite
Laurionite crystals in a vug from the Laurium district of Greece
General
Category	Halide minerals
Formula (repeating unit)	PbCl(OH)
IMA symbol	Lri[1]
Strunz classification	3.DC.05
Crystal system	Orthorhombic
Crystal class	Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m)
Space group	Pnma
Unit cell	a = 7.111, b = 9.6987 c = 4.0203 [Å]; Z = 4
Identification
Color	Colorless, white
Crystal habit	Elongated tabular prismatic crystals
Cleavage	Distinct on {101}
Tenacity	Flexible
Mohs scale hardness	3 - 3.5
Luster	Adamantine, pearly
Streak	White
Diaphaneity	Transparent
Specific gravity	6.241
Optical properties	Biaxial (-)
Refractive index	nα = 2.077 nβ = 2.116 nγ = 2.158
Birefringence	δ = 0.081
2V angle	Measured: 70°
Solubility	Sleight in cold water
References	[2][3][4][5]

Laurionite (PbCl(OH)) is a lead halide mineral. It forms colorless to white crystals in the orthorhombic crystal system and is dimorphous with paralaurionite, both members of the matlockite group.^[2]

It was first described in 1887 for an occurrence in the Laurium District, Attica, Greece, and named after the town Laurium.^[2] It occurs as an oxidation product in lead ore deposits, and is also produced on lead-bearing slag by reaction with saline solutions. It occurs associated with paralaurionite, , , phosgenite, cerussite and anglesite.^[3]

References[]