Laurionite
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.[1]
Laurionite | |
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![]() Laurionite crystals in a vug from the Laurium district of Greece | |
General | |
Category | Halide minerals |
Formula (repeating unit) | PbCl(OH) |
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 | [1][2][3][4] |
It was first described in 1887 for an occurrence in the Laurium District, Attica, Greece, and named after the town Laurium.[1] 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, penfieldite, fiedlerite, phosgenite, cerussite and anglesite.[2]
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