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Formula: Pb7O4[Mg(OH)4](OH)Cl3
Hydroxyhalide
Crystal System: Orthorhombic
Specific gravity: 6.886 calculated
Hardness: About 3
Streak: White
Colour: White to pale green
Environments
Rickturnerite is a relatively new mineral, approved in 2010.
Localities
At the Kombat Mine, Kombat, Grootfontein, Otjozondjupa Region, Namibia, a specimen purportedly from Tsumeb but more
likely from the Kombat mine was identified as parkinsonite, with a fibrous
white phase that appeared to be rickturnerite
JRS 13.30).
At the Wesley Mine, Westbury on Trym, Bristol, England, UK, yellowish grey rickturnerite was found. The colour
appears to be due to the decomposition of rickturnerite and is presumably caused by a coating of leadoxide or
carbonate
(JRS 13.30).
At the type locality, the Torr Works Quarry, Cranmore, Mendip, Somerset, England, UK, rickturnerite occurs as
pale emerald green to grey porous aggregates of disordered interwoven minute fibrous crystals with
mereheadite, cerussite,
calcite, aragonite,
mimetite, hydrocerussite,
plumbonacrite and an uncharacterised lead oxychloride, in cavities inside
a manganite and pyrolusite pod in
limestone. The crystals are typically less than 5 μm wide and 200 μm long, but they can reach 40×100 μm in cross-section
and over 1 mm in length. The green colouration is due to a small amount of copper
replacing magnesium; when pure, the mineral is whitish grey
(MM 76.59-73, JRS 13.30).
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