Datolite is a hydroborosilicate with the chemical formula CaB(SiO4)(OH). This borosilicate is quite rare, transparent, with vitreous luster, colorless to white if pure. It forms exceptional crystals in Dalnegorsk like this specimen.
The sample forms a large crystal of 3.2 cm, bright, flattened (monoclinic) greenish, bluish on small quartz crystals covered with oxides for a nice contrast.
Video of this datolite from Dalnegorsk in Russia:
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