CORUNDUM
Specimen cor-4

Dims: 4.3 x 2.2 x 2.2" (10.9 x 5.6 x 5.6 cm)

Wt: 13.9 oz. (393.0 g)

Tanzania

Maybe I should have classified this specimen as a "ruby" specimen, but I did not think that the color and quality were sufficient. This hand specimen consists of several pink Corundum crystals that are partly-embedded in a matrix of blended quartz, feldspars, and biotite mica. They are small, not exceeding 0.7" (1.8 cm) in length or 0.3" (0.8 cm) in diameter, and a few are noticeably damaged or broken. They do have excellent hexagonal prismatic form, however, with well-defined edges and reasonably clean faces that possess a waxy-to-pearly luster. All are very cloudy and translucent, and likely contain many basally-oriented internal fractures. The host rock is mostly very granular, but it appears to solidify and become more purley feldspar-bearing immediately surrounding the Corundum crystals.

Dims: 0.7 x 0.6 x 0.2" (1.8 x 1.5 x 0.5 cm)

Wt: 12.2 g

Afghanistan

A small, cut and partly-polished section of a Corundum crystal makes up this piece. It has the standard hexagonal form and a pale violet-red coloration and is translucent. Where it is not cut, the crystal is coated by a thin crust of green zoisite that is also translucent. It is hot-glued onto the foam base of a plastic specimen box. Such a piece would make an excellent stone for a pendant.

Dims: 1.2 x 0.8 x 0.7" (3.0 x 2.0 x 1.8 cm)

Wt: 11 g

Ganesh, Hunza River, Hunza, Northern Areas, Pakistan

Two distinct Corundum crystals rest in the pegmatite matrix of this thumbnail specimen. The larger of the crystals has dimensions of 0.4 x 0.3 x 0.3" (1.1 x 0.8 x 0.7 cm) and is lightly damaged in one area, whereas the smaller one is less than half that size and in excellent condition. The smaller crystal is quite warped, as it is intergrown with the larger- the larger is lightly warped and incomplete, but still has a rather well-defined hexagonal form. Both have a red-violet coloration and a greasy luster, and both are translucent and cloudy, containing many internal fractures or cleavage planes. A single, small muscovite book is also intergrown with the larger Corundum crystal.

Dims: 1.1 x 0.9 x 0.5" (2.7 x 2.2 x 1.2 cm)

Wt: 0.4 oz. (10 g) w/ foam base

Afghanistan

A partial "nodule" consisting of a Corundum core and a zoisite shell comprises this thumbnail piece. The only visible portion of the Corundum has been polished, so damage assessment is impossible. Its crystal form cannot be defined, either. The Corundum has a dull violet color and is translucent, containing many fibrous inclusions. The zoisite has a dull green color and is likewise translucent. The piece is hot-glued inside a plastic thumbnail box. Further cutting could produce a suitable stone for a pendant.

Dims: 3.1 x 0.5 x 0.5" (7.9 x 1.3 x 1.3 cm)

Wt: 0.8 oz. (23 g)

near Mount San Jacinto, Riverside County, California, U.S.A.

A single, large Corundum crystal comprises this specimen. Though broken and repaired, it has an excellent appearance. Its trigonal form is nearly perfect and its habit six-sided and pyramidal, tapering very steeply to a point. Though a small surface at its tip is uneven, it appears to be a natural flaw or very old, healed damage. There is no host rock present, and the crystal is affixed to a flat acrylic base with a removable putty.

Dims: 1.2 x 0.8 x 0.6" (3.0 x 2.0 x 1.6 cm)

Wt: 0.4 oz. (119 g) w/ foam base

Hit-Ostrov, Karelia, Kola Peninsula, Russia

A single Corundum crystal extends from the syenite base of this thumbnail piece. This crystal has dimensions of 0.6" length x 0.3" width (1.4 x 0.6 cm) and is in excellent condition. Its hexagonal form is likewise excellent, though its disjointed termination suggests breakage and healing during formation. Its dull, red-violet color and greasy luster are common for such specimens from this locality, and its is dimly to moderately translucent. Like many syenites, the base appears to contain either many other, tiny Corundums or perhaps tiny garnets. The piece is hot-glued into a plastic thumbnail box.