SILLIMANITE
Specimen sil-3

Dims: 4.2 x 2.7 x 1.0" (10.7 x 6.9 x 2.5 cm)

Wt: 9.8 oz. (279 g)

unknown

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.

Dims: 3.2 x 1.3 x 1.0" (8.1 x 3.4 x 2.5 cm)

Wt: 3.6 oz. (103 g)

Minas Gerais, Brazil

This hand specimen consists of a chunk of water-worn Sillimanite. The Sillimanite shows no definable crystal form, being water-worn, but has the compact, fibrous habit that is a primary characteristic of the specie. Its color is a deep, violet-brown and is streaked with white, and viewing the white areas, one can see the dull, silky luster caused by the fibers. There is no appreciable host rock present. Such a piece might polish to a very beautiful appearance.

Dims: 2.4 x 1.3 x 0.5" (5.9 x 3.3 x 1.3 cm)

Wt: 1.5 oz. (42 g)

Minas Gerais, Brazil

This flat hand specimen consists of a water-worn chunk of intensely compact, fibrous Sillimanite. It shows no crystal form, no fresh damage and orange, violet, brown and white hues. When viewed from certain angles, the piece exhibits a silky luster that is caused by light reflecting off of its fibers. There is no host rock present. This piece might be very attractive if it is polished.

Dims: 2.1 x 1.1 x 0.8" (5.3 x 2.7 x 1.9 cm)

Wt: 1.4 oz. (39 g)

Minas Gerais, Brazil

A worn, rounded nugget of fibrous Sillimanite makes up this hand specimen. It shows no discernable crystal form and is rounded and smooth, with a dull pearly luster. The material has colors ranging from creamy-white to dark brown with a hint of violet, and is completely opaque. A few areas show a faint schiller. There is no host material present.

Dims: 2.1 x 1.2 x 0.7" (5.4 x 3.1 x 1.9 cm)

Wt: 1.6 oz. (46 g)

Minas Gerais, Brazil

This rounded, partly tumbled Sillimanite piece is in very good condition, showing no damage, and has no visible crystal form. The patterns of pale cream and dark, violet-brown colors on its surface suggest both massive and fibrous, compact habits. At the moment, it has a dull, only slightly glossy luster, but it could easily be polished.

Dims: 1.8 x 1.3 x 0.6" (4.5 x 3.2 x 1.5 cm)

Wt: 1.0 oz. (29 g)

Minas Gerais, Brazil

This small hand specimen consists of a rounded, worn piece of compact, fibrous and massive Sillimanite. It shows no crystal form but one can see a few fibrous tendencies. The material is mostly a pale brown in color, though some darker material with a violet tinge is present. It has a dull, waxy luster, but could likely be polished to a high gloss.