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Formula: [Mg(H2O)6](Se4+O3)
Selenite
Crystal system: Trigonal
Specific gravity: 2.10 measured, 2.076 calculated
Hardness: 2½
Streak: White
Colour: Colourless
Luminescence: Not fluorescent under UV
Solubility: Slowly soluble in water and rapidly soluble in dilute hydrochloric acid at room temperature
Magnetism: Non-Magnetic
Environments
Sedimentary environments
Hydrothermal environments
Magselite is a new mineral, approved in 2025 and to date (May 2026) reported only from the type locality.
Localities
At the type locality, the Pickett Corral Mine, Montrose County, Colorado, USA, magselite occurs as a post-mining mineral in
the sedimentary uranium-vanadium deposit. It
was formed from the decomposition of ferroselite in the presence of groundwater
saturated with Mg(OH)2. Associated Minerals include andersonite,
calcite, hazenite,
mirabilite, schröckingerite,
szilagyiite and vaterite.
The magselite occurs as radiating clusters of colourless trigonal crystals to nearly 1 mm in size, or mostly inconspicuous
colourless crusts
(Mindat).
Magselite from the Pickett Corral Mine - Image
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