Hemimorphite beads are formed by a zinc-containing mineral that was once known as calamine. In 1803 the British chemist and mineralogist James Smithson discovered that there were two different minerals under the heading of calamine -- a zinc carbonate and a zinc silicate, which often closely resembled each other. The zinc carbonate was later named smithsonite in honor of Smithson, while the zinc silicate was named hemimorphite. The name calamine is no longer in use in mineralogy; now it is used only for the pink mixture known as `calamine lotion,` which contains zinc oxide and iron oxide. The name hemimorphite derives from the unusual character of its crystals the crystals are terminated by dissimilar faces. Hemimorphite is an important ore of zinc, since the mineral contains over 50% zinc. Gem-quality hemimorphite is usually blue or green, and bears some similarities to chrysocolla, smithsonite and turquoise. In an aggregate form, hemimorphite often displays bands of blue and white, or is mixed with a dark matrix. It has a hardness of 5 on the Mohs scale with perfect cleavage. Hemimorphite deposits are found in Australia, Algeria, Mexico, Namibia, the Congo, Austria, Italy and the United States.