THE MINERAL BUTTGENBACHITE

Chemistry: Cu₁₉(NO₃)₂Cl₄(OH)₃₂ - 2H₂O, Hydrated Copper Nitrate Chloride Hydroxide.
Class: Carbonates.
Subclass: Nitrates.
Uses: As a very minor ore of copper and as mineral specimens.
Specimens

Buttgenbachite is a rare copper nitrate mineral. Buttgenbachite is related to the sulfate mineral connellite. The two minerals are isostructural, share the same chemistry (except for the primary anion group) and have similar color and crystal habits. Connellite is a secondary mineral found in some unusual oxidation zones of copper deposits and is a classic mineral from the copper mines of Cornwall, England and Arizona, USA.

Buttgenbachite is much rarer than connellite. It was first discovered at Likasi, Shaba, now of the Congo. This was the only place of discovery until laboratory results proved its existence in a few samples from South Comobabi Mountains, Pima County, Arizona.

PHYSICAL CHARACTERISTICS:

Color is deep blue.
Luster is vitreous.
Transparency: Specimens are translucent to transparent.
Crystal System is hexagonal; 6 2 2.
Crystal Habits include acicular to fibrous crystals arranged in tufts, layers or radial aggregates.
Cleavage is absent.
Fracture is uneven.
Hardness is 3
Specific Gravity is approximately 3.4 - 3.5 (slightly above average for non-metallic minerals).
Streak is blue.
Associated Minerals include quartz and copper minerals.
Notable Occurrence is limited to the Likasi, Shaba, now of the Congo and South Comobabi Mountains, Pima County, Arizona, USA.
Best Field Indicators are crystal habit, color, associations and locality.