mineral
Cobaltite or cobalt-bearing calcite specimen
Likely erythrite (hydrated cobalt arsenate), Co₃(AsO₄)₂·8H₂O
AI-generated identification · may be incorrectVivid raspberry-red to purple, earthy-to-submetallic luster, commonly forming fine crusts or rosettes; Mohs hardness about 1.5–2.5, poor cleavage, and relatively high density. The granular texture and color are consistent with erythrite, though image-only identification is provisional.
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Physical properties
Vivid raspberry-red to purple, earthy-to-submetallic luster, commonly forming fine crusts or rosettes; Mohs hardness about 1.5–2.5, poor cleavage, and relatively high density. The granular texture and color are consistent with erythrite, though image-only identification is provisional.
Formation & geological history
Erythrite forms as a secondary oxidation-zone mineral from weathering cobalt-arsenide ores, commonly in hydrothermal veins; it is generally geologically young relative to its host deposit. Common localities include Bou Azzer, Morocco; Schneeberg, Germany; and Cobalt, Ontario.
Uses & applications
Primarily a collector mineral and indicator of cobalt-arsenide deposits; not generally used as an ore because it occurs in small quantities. Handle carefully because arsenate minerals may release hazardous dust.
Geological facts
Its intense color gives it the nickname “cobalt bloom.” It may occur with cobaltite, skutterudite, annabergite, quartz, and calcite.
Field identification & locations
Look for a pink-to-purple powdery coating on dense vein rock; a streak test, hardness test, density, and ideally Raman/XRF analysis are needed for confirmation. Avoid inhaling dust and wash hands after handling.
