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