Leadhillite

Leadhillite

Thin crystals of transparent leadhillite, inside a vug of galena which seems to be partially altered to cerussite. From the type locality, Leadhills, South Lanarkshire, Scotland. Size: 5.3 x 5.1 x 4.4 cm.
General
Category Carbonate minerals
Chemical formula Pb4SO4(CO3)2(OH)2
Strunz classification 05.BF.40
Identification
Color Colourless to white, grey, yellowish, pale green to blue
Crystal system Monoclinic
Luster Adamantine, resinous, pearly

Leadhillite is a lead sulfate carbonate hydroxide mineral, often associated with anglesite. It has the formula Pb4SO4(CO3)2(OH)2. Leadhillite crystallizes in the monoclinic system, but forms pseudo-hexagonal forms due to crystal twinning. It forms transparent to translucent variably colored adamantine crystals. It is quite soft with a Mohs hardness of 2.5 and a relatively high specific gravity of 6.26 to 6.55.

It was discovered in 1832 in the Susannah Mine, Leadhills in the county of Lanark, Scotland.

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References