Azurite Crystals from Romania

Azurite is a very popular mineral because of its unparalleled color, a deep blue called "azure", hence its name. Azure is derived from the Arabic word for blue. The color is due to the presence of copper (a strong coloring agent), and the way the copper chemically combines with the carbonate groups (CO₃) and hydroxyls (OH). Azurite has been used as a dye for paints and fabrics for eons. Unfortunately, at times its color is too deep and larger crystals can appear black. Small crystals and crusts show the lighter azure color well. Azurite is often associated with its colorful close cousin, malachite.

Azurite Crystals  From: Moldova Noua, Caras-Severin; Romania. Photo: László Tóth

Azurite |‪#‎Geology‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬

Formula: Cu₃(CO₃)₂(OH)₂
Color is azure, deep blue or pale blue if found in small crystals or crusts.
Luster is vitreous to dull depending on habit.
Transparency: Transparent if in thin crystals, otherwise translucent to opaque.
Crystal System is monoclinic; 2/m.
Crystal Habits crystals are irregular blades with wedge shaped terminations. Also, aggregate crusts and radiating, botryoidal, nodular and earthy masses.
Cleavage is good in one direction and fair in another.
Fracture is conchoidal and brittle.
Hardness is 3.5-4.
Specific Gravity is 3.7+ (heavier than average).
Streak is blue.
Associated Minerals are numerous and include malachite limonite, calcite, cerussite, quartz, chalcopyrite, native copper, cuprite, chrysocolla, aurichalcite, shattuckite, liroconite, connellite and other oxidized copper minerals.
Notable Occurrences include numerous localities worldwide, but special localities produce some outstanding specimens especially from Lasal, Utah; Bisbee, Arizona and New Mexico, USA; Mexico; Tsumeb, Nambia; Shaba, Congo; Toussit, Morocco; Australia and in many locations in Europe.
Best Field Indicators are color, softness, crystal habits and associations.