The Elements of Blowpipe Analysis

by Frederick Hutton Getman

Cuprite, Cu₂O, Cu . 89, O . 11.—

H = 3.5-4.0, G = 5.5-6.15.

Color, intense crimson-red. Before the Bp. on Ch. blackens and fuses quietly, and finally yields a metallic globule of copper. Before the Bp. on Ch. with Na₂CO₃ and KCN it is easily reduced.

Malachite, 2 CuO + CO₂ + H₂O, CuO . 72, CO₂ . 20, H₂O . 8.—

H = 3.5-4.0, G = 3.90-4.03.

Color, bright green. Occurs generally in mammillated concretions. Lustre, shining and fracture, silky. Heated in an ignition tube yields water and blackens. Before the Bp. on Ch. it fuses to a metallic globule. Before the Bp. on Ch. with Na₂CO₃ and KCN it is easily reduced. With borax bead gives characteristic coloration.

Azurite, 3 CuO + 2 CO₂ + H₂O, CuO . 69, CO₂ . 26, H₂O . 5.—

H = 3.5-4.0, G = 3.77-3.83.

Color, azure-blue. Occurs usually in crystallized or globular masses. Lustre, earthy or vitreous. Before the Bp. and with other reagents behaves like malachite.

Chrysocolla, CuO + SiO₂ + 2 H₂O, SiO₂ . 34.2, CuO . 45.3, H₂O . 20.5.—H = 2.0-3.0, G = 2. Color, bluish-green, closely resembling malachite. Occurs usually as an incrustation, its surface being very smooth, like enamel. In an ignition tube it blackens and yields water. Before the Bp. on Ch. in O. F. it blackens, coloring the flame bright green; in the R. F. it turns red. Before the Bp. on Ch. with Na₂CO₃ yields metallic copper. In borax bead it reacts for copper.