RHODONITE  , a member of the

pyroxene group of minerals, consisting of manganese metasilicate, MnSiO3, and crystallizing in the anorthic system . It commonly occurs as cleavable to compact masses with a rose-red colour; hence the name, from the Greek 1 YSov (a rose) . Crystals often have a thick tabular habit; there are perfect cleavages parallel to the prism faces with an angle of 87° 312' . The hardness is 52-627 and the specific gravity 3.4-3.68 . The manganese is often partly replaced by iron and calcium, which may sometimes be present in considerable amounts; a greyish-brown variety containing as much as 20% of calcium oxide is called " bustamite " ; " fowlerite " is a zinciferous variety containing 7% of zinc oxide . Rhodonite is a mineral liable to alteration, with the formation of manganese carbonate, hydrous silicate or oxides . The compact material, which is cut and polished for ornamental purposes, is often marked in a striking manner by veins and patches of these black alteration products . At Syedelnikova, near Ekaterinburg in the Urals, compact material of a good colour occurs in a clay-slate and is extensively quarried: boulders of similar material found at Cummington ,in Massachusetts (" cummingtonite f7) have also been worked as an ornamental stone . In the iron and manganese mines at Pajsberg near Filipstadt and Langban in Vermland, Sweden, small brilliant and translucent crystals (" pajsbergite ") and cleavage masses occur . Fowlerite occurs as large, rough crystals, somewhat resembling pink felspar, with franklinite and zinc ores in granular limestone at Franklin Furnace in New Jersey .