On display at the Houston Museum of Natural Science:
Azurite is a blue copper mineral formed by the oxidation of copper ores. This particular sample comes from Cochise County, Arizona.
Historically, azurite has been used ground as a pigment, in the form of beads and jewelry, and more practically as a surface indicator of copper ore bodies. Its use in everyday objects is limited, though, by its softness and reactivity. It fades in bright light, turns black (into copper oxide) when heated, and converts to malachite when exposed to water. So it needs a cool, dark, sealed storage environment — only coming out for brief display.