What is Richterite?
Richterite is a sodium-calcium amphibole known for prismatic crystals and its importance in interpreting alkaline, skarn and metamorphic rocks.
Mineralogy and crystal structure
Reference formula: Na(CaNa)(Mg,Fe)5Si8O22(OH)2. Richterite is monoclinic and compositionally variable. The selected COD model is an exact Richterite entry; fluorine-rich and other end-member compositions should be named separately when appropriate. Richterite is classified with silicates and has a monoclinic crystal system. Typical hardness is 5–6 on the Mohs scale and specific gravity is approximately 3.1–3.4.
Colour, lustre and habit
Typical colours include brown, yellow-brown, green, black. The usual prismatic, acicular, granular habit and vitreous, pearly lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Richterite forms in or is associated with alkaline igneous rocks, skarns, marbles and metamorphic rocks enriched in sodium, calcium and magnesium. Important documented localities include Canada, Russia, Italy, Finland, the United States and other amphibole-bearing districts.
A complex amphibole with elegant prismatic form
Richterite rewards collectors who want more than colour: crystal habit and host-rock chemistry reveal how sodium, calcium and fluids shaped the mineral assemblage.
Collecting and care
Protect cleavage and crystal tips from impact. Avoid cutting or grinding unknown amphibole material and retain locality information for species-level identification.
