Study on Mineralogy of Omphacite Jade

Omphacite jade or omphacitic jadeite jade, commercially named Inky Black Jade, is a virtually monomineralic rock composed of more than 90% omphacite. It has the following gemmological characters: dark green colour, high transparency (sub-transparent to translucent), vitreous lustre, micro fibrous texture, 7 of hardness, 3. 34~3. 44 of specific gravity and 1. 667~1. 670 of RI. It appears black under Chelsea Colour Filter. It is inert under LW and SW ultra violet. The results of investigation under microscope and analysis of EPMA indicate that the mineral consisting of Inky Black Jade is omphacite. X-ray power diffraction and Laser Raman spectrum also reach the same conclusion. It can be easily seperated from other simulants by the characters of specific gravity, refractive index and infrared spectrum.