Chondrodite: Gemstones Information
Facet-quality chondrodite of a transparent deep garnet-red is found in the Tilly Foster mine, Brewster, New York, USA and is one of the rarest and most beautiful of gemstones. Chondrodite, a member (with clinohumite, another rare gem mineral (q,v.) of the humite group) has the composition (Mg,Fe2)5(SiO4)2(F,OH)2 and belongs to the monoclinic system in which it crystallizes as characteristically flattened crystals.The hardness is 6–6.5 and the SG 3.16–3.26. The RI for the alpha, beta and gamma rays is 1.592–1.643, 1.602–1.655, 1.621–1.636 with a bire-fringence of 0.028–0.034, biaxial positive. Chondrodite may give a weak orange fluorescence under LWUV. Transparent to translucent orange brown specimens have recently been reported from Sri Lanka and are said to show a distinct cleavage and orange-brown to yellow-brown pleochroism.