THE MINERAL BROOKITE

Dims: 2.4" x 1.4" x 1.1" (6.1 x 3.6 x 2.8 cm)

Wt: 1.53 oz. (43.5 g)

Mose Hill, Magnet Cove, Arkansas, U.S.A.

This small hand specimen from the well-known Magnet Cove locality consists of several pseudohexagonal dipyramidal Brookite crystals; these rest on a base made up of several intersecting, dark-gray quartz crystals. The largest Brookite crystal has dimensions of 0.3 x 0.3 x 0.2" (0.8 x 0.8 x 0.5 cm) and shows a much less perfect form than the smaller crystals, but it seems to show evidence of an accompanying sulfide mineral, as there is a small golden metallic patch of material on it, along with some blue iridescence. Other than that, all of the crystals are black, opaque, and have a luster that hangs between adamantine and submetallic. There are at least 12 of them, and the intergrown quartz crystals on which they rest have a dull, waxy-to-pearly luster and are opaque. They also have discernable but very warped hexagonal prismatic forms; I think that these traits are related to the inclusions that give them their dark gray color. A few of the quartz crystals show fresh breakage, but most are undamaged. It has not been easy for us to find Brookite specimens, even from this nearby locality.

Dims: 1.3 x 1.2 x 0.8" (3.3 x 3.0 x 2.0 cm)

Wt: 13.1 g

Magnet Cove, Arkansas, U.S.A.

At least 6 small Brookite crystals rest on the crystalline quartz base of this thumbnail specimen. Two of the smaller crystals are broken and incomplete, but the largest ones are intact and in excellent condition. They have a rather odd octahedral form that is common for Brookite from this locality- two opposing corners on each crystal are flattened so that each appears nearly tabular in form. Otherwise, their edges are well-defined and their faces are heavily patterned but clean. All have the standard black color and a slightly dull adamantine luster. The base on which they rest is made up of at least 3 intersecting quartz crystals that resemble "elestial" quartz in form, with small multiple terminations and growth patterns. They have a gray color and a dull, waxy luster.

Dims: 1.2 x 0.9 x 0.6" ( 3.0 x 2.3 x 1.5 cm)

Wt: 10.1 g

Mose Hill, Magnet Cove, Arkansas, U.S.A.

Two Brookite crystals rest on the crystalline quartz base of this specimen. Both are in excellent condition, showing no damage. The larger of these crystals has dimensions of 0.5 x 0.4 x 0.2" (1.3 x 1.0 x 0.5 cm), and the smaller measures 0.3 x 0.3 x 0.2" (8 x 8 x 4 mm). Their cube-based form is rather warped but normal for pieces from this locality- two opposing corners on each crystal did not form, producing 2 large, opposing and heavly-patterned faces. Both have the obligatory black color and a luster that is either waxy or adamantine, depending on the face viewed. The base consists of a few intergrown quartz crystals that have a dull gray color and a very dull, waxy luster.