Yugawaralite: Gemstones Information
Yugawaralite is CaAl2Si6O164H2O and a member of the zeolite group.It forms flat monoclinic tabular transparent to translucent colourless to white crystals, often nearly parallel in groups with hardness 4.5–5 and SG 2.20–2.23. The RI for the alpha, beta and gamma rays is 1.492–1.496,1.497–1.499 and 1.502–1.504, biaxial negative or positive with birefringence 0.009. Yugawaralite occurs as crystals lining cavities, typically deposited in active geothermal areas. Faceted stones will probably have come from the Khandivali quarry near Mumbai, India.