Ferrisurite

ferrisurite

covellite

chalcocite

mimetite

Images

Formula: Pb2.4Fe3+2Si4O10(CO3)1.7(OH)3).nH2O
Phyllosilicate (sheet silicate)
Crystal system: Monoclinic
Specific gravity: 4.0 measured, 3.89 calculated
Hardness: 2 to 2½
Streak: Greenish yellow to olive-green
Colour: Forest-green to light yellow-green
Luminescence: No fluorescence under long wave or short wave UV
Solubility: Effervesces in cold 1:1 hydrochloric acid, leaving a gelatinous residue
Common impurities: Na,Mg,Ba,Pb
Environments

Metamorphic environments
Hydrothermal environments

Localities

At the type locality, the Shirley Ann group, Big Dodd Spring, Ubehebe Mining District, Cottonwood Mountains, Panamint Mts, Inyo County, California, USA, the Shirley Ann claim exploits an oxidised lead deposit in contact metamorphosed and faulted shaly and silty limestone. The deposit is notable for an abundance of copper minerals and scarcity of zinc minerals relative to the larger mines in the area. The most prominent ore mineral is cerussite, which replaces galena. The mineral assemblage includes quartz, calcite, covellite, chalcocite, anglesite, wulfenite, hematite, limonite, malachite and other supergene copper minerals.
Specimens containing ferrisurite were collected at the mine dump. Minerals associated with ferrisurite include galena, pyrite, chalcopyrite, covellite, chalcocite, quartz, calcite, hematite, cerussite, mimetite, wulfenite and malachite. Ferrisurite probably formed during the early stages of oxidation as a consequence of the alteration of silicates in close proximity to galena.
Ferrisurite occurs as compact radial aggregates of fibres embedded in quartz and cerussite and as tapering feathery crystals in radiating groups in vugs. Maximum crystal dimensions are 2 mm x 0.01 mm x 0.04 mm. Individual ferrisurite crystals are transparent to translucent with light yellow-green colour and greenish yellow streak. Compact radial aggregates have a medium to dark forest green colour and olive green streak (AM 77.1107-1111).
Ferrisurite from the Shirley Ann group - Image

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