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Formula: Zn3V2O7(OH)2.2H2O
Hydrated normal vanadate,
volborthite group
Crystal System: Trigonal
Specific gravity: 3.37 measured, 3.375 calculated
Hardness: 3
Streak: Pale yellow-orange
Colour: Pale orange-yellow
Solubility: Dissolves rapidly in cold hydrochloric acid
Environments
Sedimentary environments
Hydrothermal environments
Localities
At the type locality, the Blue Cap mine, La Sal Creek Mining District, San Juan County, Utah, USA, martyite
occurs in association with gypsum,
rossite, pyrite,
montroseite and
magnesiopascoite on a
vanadium-uranium oxide-replacement assemblage developed at the expense of
organic material. All samples of martyite were recovered from a single isolated pillar in the mine. Other
minerals identified from the mine are brochantite,
calcite, coffinite,
devilline, dickthomssenite,
dolomite, lasalite,
navajoite, sherwoodite,
uraninite, uranopilite and
zeunerite.
Uranium–vanadium mineralisation in the mines of the area occurs in certain
layers of the sandstone. Carbonaceous material in these layers is
considered to have created a reducing environment, which caused the precipitation of uranium and
vanadium oxides, such as
uraninite, corvusite and
montroseite, from solution. Martyite,
magnesiopascoite and
rossite appear to have formed from post-mining leaching and oxidation of
vanadium oxides by circulating groundwater
(CM 46.687-692).
Martyite from the Blue Cap Mine - Image
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