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Formula: CaCu(U6+O2)(PO4)2·4H2O
Hydrated normal uranyl phosphate
Crystal System: Monoclinic
Specific gravity: 3.71 calculated
Hardness: 3 to 3½
Streak: White
Colour: Apple-green, lime-green
Solubility: Readily soluble in dilute HCl and HN03.
RADIOACTIVE
Environments
Plutonic igneous environments
Pegmatites
Ulrichite is a rare mineral, to date (March 2024) reported only from the type locality.
Localities
The type locality, the Lake Boga granite, Lake Boga, Swan Hill Rural City, Victoria, Australia, is a very large intrusion
formed about 365 million years ago. The entire outcrop of the granite is
overlain by sediments in places up to several hundred meters thick. The sole exposure into the
granite is the Lake Boga quarry, where the sediment is only a few metres
thick. The uppermost levels of the granite exhibit
aplite veins, pods of
pegmatite, and numerous miarolitic cavities, features that are
characteristic of the uppermost levels of a granite magma intruded to
shallow crustal levels
(R&M 97.1.28-32).
Ulrichite occurs here typically as radiating sprays of apple-green to lime-green acicular crystals up to 1 mm long and
0.05 mm thick, and also as flat prisms. It occurs with turquoise and
chalcosiderite in miarolitic cavities in
pegmatoidal granite
in the quarry. Other associated minerals include fluorapatite,
libethenite, cyrilovite,
torbernite and saléeite
(AM 75.243).
Ulrichite from Lake Boga - Image
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