It forms from the oxidation of primary copper ores. Color is typically blue to bluish green. Luster is vitreous. Crystals are transparent to translucent. Cleavage is poor in two directions parallel to the prism faces.
Fracture is uneven to conchoidal.
Hardness is 2 - 2.5. Streak is pale blue. There is no reaction to acid as is true with azurite . Associated Minerals are clinoclase , azurite , malachite , caledonite and linarite and other oxidation zone copper ore minerals. Best Field Indicators are crystal habit, color, low density, non reaction to acids, associations and streak.