Hemimorphite, zinc silicate, is sometimes called 'calamine'. It is used as an ore of zinc, and is a common mineral in the secondary alteration zones of lead and zinc deposits. The name refers to the specific symmetry of its crystals. Some of the most spectacular come from the famous zinc mines of Mexico, including this material from Mina Ojuela, at Mapimi, Mexico. Hemimorphite can also form thick veins, typically colored blue by copper.