The new organic mineral ravatite (analyzed as C 14.1 H 9.9 , idealized formula C 14 H 10 ), identical with synthetic phenanthrene, is described as a sublimation product caused by the natural combustion of a brown coal seam near Ravat/Tadzhikistan (southwestern Tjan' Shan'). It forms thin, platelet-like individuals with diameters of mainly a few hundred micrometers which are usually aggregated to thin crusts on a bituminous, H 2 SO 4 -impregnated coaly-earthy material. Ravatite is colourless, or―dependent on the amount of coaly, gas and other inclusions―white to pale grey and transparent to translucent. It shows a vitreous to wax-like lustre. Ravatite has a monoclinic lattice (space group P2 1 ) with a o = 8.392(5)A; b o = 6.181(3)A; co = 9.558(5)A; β = 98.48(12)°; V = 490.4(4)A 3 ; Z = 2. The observed strongest five X-ray powder diffraction lines [d in A (I rel ) (hkl)] are: 9.434(100)(001); 4.028(13)(201); 4.941(11)(110); 4.724(11)(002); 3.371(10)(211). The Mohs hardness is about 1; the calculated and the measured densities are 1,207(1) and 1.11(2) g/cm 3 , respectively. Ravatite shows a whitish-yellow fluorescence under ultraviolet light. The initial temperature of melting is 94.3 °C. Infrared absorption and Raman data do not differ significantly from data of synthetic phenanthrene
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Nasdala et al. (1993) studied this question.