THE MINERAL CORNETITE

Chemistry: Cu3PO4(OH)3 , Copper Phosphate Hydroxide.
Class: Phosphates
Uses: mineral specimens.
Specimens

Cornetite is a rare secondary copper mineral that is noted for its deep blue, green-blue to green color. It is found in highly weathered, oxidation zones of copper sulfide ore bodies. It has a good deep color, nice crystal forms and an attractive sparkle, all the ingredients for a popular collection mineral.

PHYSICAL CHARACTERISTICS:

Color is dark blue, green-blue to green.
Luster is vitreous.
Transparency: Specimens are translucent.
Crystal System: is orthorhombic; 2/m2/m2/m
Crystal Habits include crystals that are short, rounded, nearly diamond-shaped prisms that are terminated by a dome with trapezohedral faces, also as tiny crystalline druzes, fibrous masses and crusts.
Cleavage is absent.
Fracture is uneven.
Hardness is 4.5
Specific Gravity is approximately 4.1 (above average for translucent minerals)
Streak is blue.
Associated Minerals are limonite, libethenite, malachite, pseudomalachite, brochantite and other secondary copper ore minerals.
Notable Occurrences include Shaba, Congo; Bwana Mkubwa, Zambia and Empire Nevada Mine, Yerington,Nevada.
Best Field Indicators are color, streak, crystal habits, associations and density.