Vesuvianite

Vesuvianite: Calcium, Magnesium, Iron and Aluminium hydroxide silicate. It crystallised in the Tetragonal System in prismatic and squat crystals. It can also be found in column aggregates and in compact granular masses; it can be brown, green, rarely yellow, red and light blue; 3,32-3,47 gr/cm3 density, 6-7 Mohs hardness, highly variable 1.674-1.761, 1.655-1.750 refraction indexes.

Rob Lavinsky, iRocks.com – CC-BY-SA-3.0 [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons
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