Azurite
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Azurite is a soft, deep-blue copper mineral produced by weathering of copper ore deposits. During the early 19th century, it was also known as chessylite, after the type locality at Chessy-les-Mines near Lyon, France. Wikipedia
Element symbol: Azu
Category: Carbonate mineral
Cleavage: Perfect on, fair on, poor on
Color: Azure-blue, dark to pale blue; pale blue in transmitted light
Crystal habit: Massive, prismatic, stalactitic, tabular
Crystal system: Monoclinic
Fracture: Conchoidal