A massive pale reddish-brown of pure microcrystalline Indialite. This material is probably the richest Indialite ever found.
Formed by fusion and recrystallization of sedimentary rocks as a result of the burning of underlying coal seams. High temperature polymorph of cordierite.Hardness is 7-7.5.Formula Mg2Al4Si5O18 .
From Durham Ranch, Wright, Reno Junction, Campbell Co., Wyoming / USA