Dims: 4.2 x 2.7 x 1.0" (10.7 x 6.9 x 2.5 cm)
Wt: 9.8 oz. (279 g)
This specimen consists of a chunk of compact, fibrous Sillimanite, which is sometimes called fibrolite. It shows obvious crystalline tendencies, but no definite orthorhombic form. The fibers are not straight- they take on an undulating, slightly serpentine curve. The material has a pale gray-green coloration and a pearly luster and is translucent, though the piece as a whole is essentially opaque. There are traces of a black mineral embedded in the Sillimanite, but I cannot identify it. There is no host rock present, however.