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Susannite

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Susannite
Susanite with macphersonite and lanarkite from the Susanna Mine, Leadhills
General
CategoryCarbonate minerals
Formula
(repeating unit)
Pb4SO4(CO3)2(OH)2
Strunz classification5.BF.40
Crystal systemTrigonal
Space groupTrigonal - rhombohedral
H-M symbol (3)
Space group: R3
Unit cella = 9.07, c = 11.57 [Å]; Z = 3
Identification
ColorColorless, white, pale green, pale yellow, brown
Crystal habitOccurs as equant to acute rhombohedral crystals
Cleavage{0001} perfect
Mohs scale hardness2.5 - 3
LusterAdamantine, resinous
DiaphaneityTranslucent
Specific gravity6.55
Optical propertiesUniaxial (anomalously biaxial)
Refractive index1.96
References[1][2][3]

Susannite is a lead sulfate carbonate hydroxide mineral. It has the formula Pb4SO4(CO3)2(OH)2. Susannite is the higher temperature phase of the two and forms above 80 °C when fluids oxidize the lead ore deposits. It is trimorphous with leadhillite and macphersonite.[3]

Susannite crystallizes in the trigonal system. It is quite soft with a Mohs hardness of 2.5 to 3.0 and a relatively high specific gravity of 6.57.

An old beam engine to dewater a lead mine at nearby Wanlockhead

It was discovered in 1827 in the Susannah Mine, Leadhills in the county of Lanark, Scotland.[2] In addition to the type locality in Scotland, it has also been reported from various locations in Germany, the Tiger Mine in Pinal County, Arizona, from Iporanga, Sao Paulo, Brazil, and the Tsumeb mine of Namibia.[3]

See also

References