BRUCITE
Specimen bru-4

Dims: 4.9" x 4.3" x 2.0"(12.4 x 10.9 x 5.1 cm)

Wt: 1 lb., 0.2 oz.(458 g)

Asbest, Ekaterinberg, central Urals, Russia

This Brucite specimen lacks any definite crystal form, but is quite large and has an interesting green-blue color. It takes the form of a foliated mass that shows evidence of crystalline tendencies, but not clearly. It has a generally waxy luster, except for areas that show its perfect cleavage, which have a pearly luster. It is translucent, but large parts of it are opaque. It seems as if there is another mineral in the specimen, but most likely it is nearly pure Brucite. Probably the most impressive aspect of this specimen, other than what it actually is, is its Russian locality, which I have never heard of before.

Dims: 1.3" x 1.0" x 0.5" (3.3 x 2.5 x 1.3 cm)

Wt: 8.8 g

Cedar Hill Quarry, Lancaster County, Pennsylvania, U.S.A.

This small thumbnail specimen consists of 3 intergrown and incomplete Brucite crystals. The largest of them has a diameter of 1" (2.5 cm) and a thickness of 0.2" (5 mm), and the other two are about half that diameter. All occur in a flattened trigonal tabular form that has a rounded but definable hexagonal outline. Damage to each is considerable, but does not directly affect their edges. All have a pearly-white color and a dull, silky luster on their intact surfaces; the surfaces that have undergone cleavage show a brighter, pearly luster that makes me think of mica. Though they are rather milky in appearance, they still show a dim translucence. The base on which these crystals rest appears to be made up almost entirely of bits of other broken Brucite crystals.

Dims: 2.7 x 2.3 x 1.1" (6.9 x 5.8 x 2.8 cm)

Wt: 2.57 oz. (72.8 g)

Boulby Potash Mine, Cleveland, Yorkshire, England

Though this specimen is composed almost entirely of Brucite, only a small percentage of the material shows any crystalline form. These formations are confined to two opposing surfaces on the specimen, which is likely part of a crust One of the surfaces shows tiny, botryoidal orbs that are heavily intergrown and dusted with microscopic crystals, giving them a slight sparkle. These orbs do not exceed 3 mm in diameter, and they show a few small areas of noticeable damage. However, these damaged areas allow one to see a few cross-sections of crystals, which contain visible concentric layering. Under magnification, one can see that each of these nodules is actually a cluster, of compact, fibrous, radial needles. The opposing surface also shows some definite botryoidal form, but these orbs are covered with larger, visible trigonal prismatic crystals that are transparent, quite clear, and possess a vitreous luster. All of the material has a uniform pale-green coloration that is slightly to intensely rust-stained in several areas.

Dims: 3.7 x 2.7 x 2.5" (9.4 x 6.9 x 6.4 cm)

Wt: 1 lb., 2.1 oz. (514 g)

Gabbs Valley Mine, Meneral County, Nevada, U.S.A.

This large hand specimen consists simply of a chunk of massive, shapeless Brucite. There is no evidence of either crystal form or crystalline tendencies present, and all surfaces are rough, dull, and uneven. The material has a dingy pale yellow-gray coloration, though there is a patch of almost black material at one end, and is basically opaque. There is no host or base rock present. We have left the original label (made of a strip of surgical tape) on the specimen; it is very difficult to read the locality off of it, though, because it is badly stained and the lettering is somewhat faded.

Dims: 1.25x1.17x0.55" (3.17x2.98x1.41cm)

Wt: 0.22oz (6.15g)

San Benito County, California, USA

A single large ball of brucite rests on a sliver of matrix. The brucite is off-white (just a hint of brown), and the individual crystals in the perfect radial cluster appear transparent, with triangular terminations. The brucite and the matrix are covered with a scattering of tiny white artinite clusters, some of which are broken open, revealing the radial pattern of fine white fibers of artinite.