Tincalconite

Tincalconite is a hydrous sodium borate mineral closely related to borax, and is a secondary mineral that forms as a dehydration product of borax. Its formula is Na2B4O7·5H2O or Na2[B4O5(OH)4]·3H2O. Tincalconite typically occurs as a fine grained white powder. It crystallizes in the hexagonal crystal system and has been found as primary euhedral
Found on http://en.wikipedia.org/wiki/Tincalconite

tincalconite

a borate mineral, hydrated sodium tetraborate (Na2B4O5(OH)43H2O), that is found in nature only as a dull, white, fine-grained powder; colourless ... [1 related articles]
Found on http://www.britannica.com/eb/a-z/t/52
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