Bandylite

bandylite

atacamite

eriochalcite

starkeyite

Images

Formula: CuB(OH)₄Cl
Anhydrous borate containing halogen
Specific gravity: 2.81
Hardness: 2½
Streak: Pale blue
Colour: Deep blue with greenish portions becoming greener with atacamite inclusions, blue in transmitted light
Solubility: Decomposed by water, leaving a residue of green copper borate. Readily soluble in NH₄OH, to form an intense blue solution. Less readily soluble in hydrochloric or nitric acid (Mindat)
Common impurities: Fe
Environments

Hydrothermal environments

Bandylite alters readily to eriochalcite upon exposure to air (Mindat).

Localities

At Taltal, Antofagasta Province, Antofagasta, Chile, bandylite occurs with starkeyite (HOM).

At the type locality, the Queténa mine, Toki Cu deposit, Chuquicamata District, Calama, El Loa Province, Antofagasta, Chile, bandylite is of secondary origin, occurring in a leached zone above massive iron sulphates. It occurs as tabular or pyramidal crystals to 5 mm and almost lichen-like radial clusters in joints in the rock. Associated minerals include antofagastaite, atacamite and eriochalcite (AM 23.85-90, HOM, Mindat).

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