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 crystals are monoclinic. Large crystals are dark blue, often prismatic. Azurite is destroyed by heat, losing carbon dioxide and water to form black, copper(II) oxide powder. Characteristic of a carbonate, specimens effervesce upon treatment with hydrochloric acid.