This is the mineral Azurite. Its name is derived from the word azure, which means blue. The mineral’s distinctive color comes from the presence of Copper ions within its chemical structure. It’s a relatively soft mineral, ranking 3.5 to 4 on Mohs hardness scale, and produces a blue streak when drawn across a streak plate. Azurite has a vitreous, or glassy, luster that increases with polishing. It exhibits good cleavage in one direction and thus readily splits along one plane. Its specific gravity is 3.8. Azurite belongs to the Carbonate chemical family. All Carbonate minerals contain a Carbonate ion. Carbonate ions are compounds made of one Carbon atom surrounded by three Oxygen atoms. Carbonate ions are unstable in the presence of hydrochloric acid. The acid reacts with the Carbonate ions to produce Carbon Dioxide in an effervescent, or bubbling, reaction. Geologists can thus test for Carbonate minerals using an acid test, which is conducted by placing several drops of Hydrochloric Acid on a specimen and watching for effervescence. If fizzing and bubbling occur, a geologist may correctly deduce that the sample belongs to the Carbonate chemical family. People have used Azurite for millennia, mostly as a blue pigment for cloth and paint. Lapidaries, people who cut, shape, and polish stones and minerals, still create prized decorative shapes using this mineral. They carry on traditional artisanal skills first cultivated nearly 4,000 years ago in Ancient Egypt.