Mellite: Gemstone Information
Mellite is organic with the composition Al2C6(COO)616H2O and forms transparent honey yellow or reddish prismatic or dipyramidal crystals or masses of the tetragonal system. The hardness is 2–2.5 and the SG 1.58–1.64. The RI for the ordinary and extraordinary rays is 1.539–1.541 and 1.509–1.511, uniaxial negative with birefringence 0.028–0.032. Weak fluorescent effects may be seen. Mellite is found in brown coal and/or lignite deposits, material coming from Artern, Thuringia and Bitterfeld,Saxony-Anhalt, Germany.