Exceptional azurite crystals on matrix from the famed Clara Mine, Wolfach, Black Forest, Baden-Württemberg, Germany
Azurite is a soft, deep-blue copper mineral produced by weathering of copper ore deposits. Azurite is one of two basic copper(II) carbonate minerals, the other being bright green malachite. Azurite crystals are monoclinic. Large crystals are dark blue, often prismatic. Azurite specimens can be massive to nodular. They are often stalactitic in form. Specimens tend to lighten in color over time due to weathering of the specimen surface into malachite. Azurite is soft, with a Mohs hardness of only 3.5 to 4.