Cabrerite

cabrerite

hornesite

annabergite

nickel

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Formula: NiMg2(AsO4)2.8H2O
Hydrated arsenate, vivianite group, nickel-bearing mineral
Not to be confused with Cabrerite (of Dana), a historic name for a magnesium-bearing variety of annabergite.
Crystal System: Monoclinic
Specific gravity: 2.93 measured, 2.915 calculated
Hardness: 2½
Streak: Pale green to white
Colour: Green
Luminescence: No fluorescence under UV
Solubility: Dissolves slowly in dilute hydrochloric acid at room temperature
Environments

Hydrothermal environments?

Cabrerite as described here is a new mineral, approved in 2024 and to date (April 2025) reported only from the type locality.

Localities

At the type locality, Nickel mine (Cottonwood Canyon Nickel Mine), Bolivia, Cottonwood Canyon, Churchill County, Nevada, USA, cabrerite occurs in divergent groups of green blades up to 1 mm long that are elongated and striated parallel to their length. Cabrerite is the ordered intermediate between hörnesite and annabergite. Associated minerals include calcite and dolomite (AM 110.4.643-649, Mindat).

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