Calamine
Calamine (which generates piezoelectricity*) was originally called smithsonite, named after the mineralogist Smithson*, who founded the Smithsonian Institute. Until the 1880s, it was the chief source of zinc, until it was replaced by sphalerite, otherwise known as zinc blende.
As an ore and carbonate of zinc, calamine is normally found in limestone where there are zinc or oxidised zinc ore deposits and it is commonly associated with sphalerite, gelena and calcite.
There are few locations where calamine deposits can be found in sufficient quantity for mining to be commercially viable, the most important being Sardinia, Laurium in Greece, Bytom and Tarnowskie Góry in Poland and Leadville, Colorado.
The surface of the mineral reflects the light, giving it a glassy sheen that is usually grey, brown or greyish white in colour. Occasionally, calamine can be translucent, and is sometimes yellow or green, the green variety being used decoratively, in the manufacture of ornaments.
The composition of calamine is ZnCO3, hardness 4.0-4.5 and specific gravity 4.4. Its crystal system is hexagonal and it has perfect cleavage.
ONELINER: Calamine
OTHER CONNECTIONS: None
BIBLIOGRAPHY:
Encyclopaedia Britannica
Calamine is either a mixture of zinc oxide (ZnO) with about 0.5% ferric oxide (Fe2O3)[1][2] or a zinc carbonate compound.[3][4] It is the main ingredient in calamine lotion and is used as an anti-pruritic (anti-itching agent) to treat conditions such as sunburn, rashes, poison ivy, poison oak, chickenpox, and insect bites and stings.[5][6][7][8][9][10] It is also used as a mild antiseptic to prevent infections that can be caused by scratching the affected area, and an astringent to dry weeping or oozing blisters and acne abscesses.[11]
Medical uses[edit]
In a September 2, 2008 document, the U.S. Food and Drug Administration recommended applying topical OTC skin protectants, such as calamine, to relieve the itch caused by poisonous plants such as poison ivy,poison oak, and poison sumac.[13]In a 1992 press release, the U.S. Food and Drug Administration announced that no proof had been submitted showing calamine to be safe for use or effective in treating bug bites, stings, and rashes from poison ivy,poison oak, and poison sumac.[12] The press release listed a total of 415 over the counter (OTC) drug ingredients which the FDA proposed banning for specific uses which are as yet unproven.