Anorthite -

silicate mineral from the cluster belongs to a group plagioklazów, very rare. Dissolved in hydrochloric acid . Tablet forms crystals, krótkosłupkowe, usually zbliźniaczone . Crystals generated are found occasionally. Mineral is brittle, transparent. Creates mixed crystals with Albite (0 -10%). Occurs in some igneous rocks (such as gabbro, basalt, Norite, Anorthosite) and metamorphic. Beautiful crystals occur in lapillach volcanic Mount Vesuvius.