The richterite group includes
Ferro-richterite Na(NaCa)Fe2+5Si8O22(OH)2 and
Potassic-fluoro-richterite K(NaCa)Mg5Si8O22F2
Inosilicates (chain silicates), amphibole group.
Specific gravity: 2.97 to 3.45
Hardness: 5 to 6
Streak: White
Colour: Brown to brownish-red, rose-red, or yellow, grey-brown, and also pale to dark green. dark green blue and grey blue

Plutonic igneous environments
Volcanic igneous environments
Metamorphic environments

Richterite occurs in syenite, in basalt, in carbonatites, in gneiss and in impure metamorphosed limestone due to regional metamorphism, and in meteorites and lunar basalts (AM59.518, Mindat).
Associated minerals include leucite, diopside, forsterite, calcite, apatite, natrolite, phlogopite, cristobalite, enstatite and plagioclase (HOM).
Magnesium-rich richterites occur in thermally metamorphosed limestone, and they are also found in skarn associated with iron-manganese deposits, and in carbonate veins in ultramafic rocks rich in pyroxene (Dana).
Potassium-rich richterite is found in leucite rocks, often enclosing diopside and leucite (Dana).
At Earle Farm, Wilberforce and at Tory Hill, Ontario, Canada, richterite occurs as crystals in calcite (Dana).

Common impurities: Ti,Al,Cr,Mn,Ni,Sr,K,F,Cl,H2O

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