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Formula: K2Fe2+[(UO2)(SO4)2]2(H2O)8
Uranyl sulphate
Crystal System: Orthorhombic
Specific gravity: 3.31 measured, 3.298 calculated for the empirical formula and 3.330 for the ideal formula
Streak: Very pale yellow
Colour: Yellow
Luminescence: Not fluorescent under UV
RADIOACTIVE
Environments
Oldsite is a new mineral, approved in 2021 and to date (April 2023) reported only from the type locality.
Localities
At the type locality, the North Mesa Mine Group, Temple Mountain Mining District, Emery County, Utah, USA, oldsite is found
as a secondary mineral occurring with
alum-(K), halotrichite,
metavoltine, quartz,
römerite, stanleyite,
sulphur, szomolnokite and
mathesiusite. It forms rectangular blades reaching ~0.3 mm in length. Crystals are
yellow in colour, transparent with a vitreous lustre. Crystals are brittle with irregular, splintery fracture
(MM 87.1.151-159).
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