CHALCOALUMITE

Chalcoalumite is a hydrous copper aluminum hydroxy-sulfate mineral (CuAl₄SO₄(OH)₁₂·3H₂O). It's a secondary mineral, forming in the altered (oxidized) zone of copper deposits. It has a nonmetallic luster, a greenish to bluish color, a whitish to bluish-white streak, and is fairly soft (H = 2.5). Chalcoalumite forms moderately thin crusts of tiny fibers. Fragments of chalcoalumite have been observed to be flexible (elastic).

Chalcoalumite (bluish) on limonite (yellowish-brown) from a copper mine near Bisbee, Cochise County, southeastern Arizona, USA

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