Gmelinite
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Gmelinite is one of the rarer of the zeolite minerals being a hydrated silicate of calcium, aluminium and either sodium or potassium with formula: (Na2,Ca)Al2Si4O12·6H2O.
It forms striking crystals, shallow, six sided double pyramids, it can be colorless, white, pale yellow, greenish, orange, pink, and red. They have been compared to an angular flying saucer.
The mineral is named after the German chemist and mineralogist Cristin Gottlieb Gmelin (1792-1860).
References
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