THE MINERAL FERBERITE

Dims: 1-1/2" x 7/8" x 1"

Wt: 2.47 oz

Potosi Deposit, Bolivia

This little one is heavy! It is an incomplete crystal of Ferberite with evidence of 5 crystal faces, not quite enough to figure out exactly what variety of crystal form it was trying to take up. The parts of the faces that show are clean, with the exception of one, which either shows a very disjointed period of growth(according to the bizarre patterns), or a paritally-healed fracture. It is colored black and has a submetallic luster. From the way one face of it looks, it may have good cleavage in at least 1 direction.

Dims: 1-1/2" x 1" x 1"

Wt: 1.97 oz

Potosi Deposit, Bolivia

Though quite small, this Ferberite specimen is impressive with its 3 almost-complete, well-formed crystals. The largest is approx. 1" x 1" x 1/2". Their color is black, and they have a submetallic luster. The crystals' shapes are all the same, a tabular prism that certainly doesn't seem symmetrical to me! It's certainly a beautiful specimen, and is probably one of the heaviest thumbnail specimens that I've come across!

Dims: 1.7" x 0.8" x 0.7" (4.3 x 2.0 x 1.8 cm)

Wt: 1.75 oz. (49.6 g)

Yaogangxian Mine, Yizhang County, Hunan Province, China

This simple specimen consists of a parallel association of four long, tabular Ferberite crystals with angled or domed terminations. They have generally good form, though all show some damage to their terminations, and one is severely damaged. Their color is basically black, though a few red-brown highlights are visible in damage areas, their luster is vitreous, and all are completely opaque. A thin crust covers most of one side of each crystal, and seems to be made up of tiny quartz crystals mixed with muscovite platelets. It is one of the more well-defined Ferberite specimens that I have come across.

Dims: 1.7 x 1.6 x 1.1" (4.3 x 4.1 x 2.8 cm)

Wt: 2.33 oz. (66.2 g)

Yaogangxian Mine, Yizhang County, Hunan Province, China

This beautiful thumbnail specimen consists of a single Ferberite crystal that is partially coated with a crust of crystalline calcite. The crystal has dimensions of 1.6 x 1.4 x 0.4" (4.1 x 3.6 x 1.0 cm) and is in excellent condition, being mostly protected by the calcite. It shows a good monoclinic form, and though only one of the larger faces is completely visible, the crystal's general shape is easily visible. It has a black coloration and a bright, adamantine luster. The calcite that coats it has a bright, white color and a pearly-to-vitreous luster, and consists of crystals ranging in size from less than 1 mm to 0.2" (5 mm) in diameter. They have an excellent "nail-head" form, and many of the larger ones show visible phantoming. Many tiny chalcopyrite nodules are scattered on top of the calcite, and there are a few prismatic quartz crystals visible, too. They have good hexagonal form and are intergrown side by side, so as to appear to be one crystal with two terminations. It is also double-terminated, so three terminations are visible! Several tiny partial books of muscovite are embedded in the one clear face of the Ferberite crystal, and there are a few shards of other Ferberites that are partially covered by the calcite on the other side.

Dims: 3.0 x 2.9 x 1.6" (7.6 x 7.4 x 4.1 cm)

Wt: 1 lb., 3.6 oz. (556 g)

Yaogangxian Mine, Yizhang County, Hunan Province, China

This hand specimen consists of several Ferberite blades that are all partly intergrown and embedded in a massive and crystalline quartz host rock. These crystals reacha lengths of 2.8" (7.1 cm) and are in moderately fair condition, as most are broken and missing their terminations. Where intact, they have very good monoclinic form, with relatively well-defined edges and striated but clean faces that possess a bright, submetallic luster. All have a dark gray-black coloration and are thoroughly opaque. Portions of some of the more exposed Ferberites are coated with crusts made up of tiny, intergrown calcites. Several larger, tabular calcite "nailheads" are partly intergrown on the quartz base, which contains a few noticeable crystals.

Dims: 2.8 x 1.6 x 0.8" (7.1 x 4.1 x 2.0 cm)

Wt: 2.93 oz. (83.3 g)

Yaogangxian Mine, Yizhang County, Hunan Province, China

At least 3 Ferberite crystals make up this thumbnail specimen. These crystals do not exceed 1.5 x 1.0 x 0.2" (3.8 x 2.5 x 0.5 cm) and are in moderately good condition, as they show considerable damage. Part of this damage is in the form of missing terminations, but this particular part occurred prior to mining- close examiniation will show that several tiny crystal faces have formed on these breakage planes. Where intact, the Ferberites have reasonably good form, with well-defined edges and striated, moderately clean faces that possess a bright submetallic luster. They have the standard black color and are, of course, opaque. They are partly coated with a "druse" that is made up of many intergrown books of muscovite. A few small, flattened round dolomite clusters rest on it, and it is in turn mostly covered by a fine druse of very tiny fluorite cubes. A few of these cubes are quite large, measuring as much as 0.3" (8 mm) along an edge. They have good form and a pale violet color, and even show some color zonation that is indicative of phantoms!

Dims:2.5x1.7x1.4" (6.4x4.3x3.6 cm)

Wt: 6.3oz. (179g)

Yaogangxian Mine, Yizhang co., Hunan prov., China

This specimen consists of a single large ferberite crystal on a bit of quartz and pyrite matrix. The ferberite crystal is somewhat distorted, and has a rough termination; however, it shows the vertical striations typical for the species. On the back of the large ferberite crystal are a couple of small (0.2", 0.5cm) fully terminated crystals of ferberite. Around the base of this specimen are a number of complete (as well as some partial) quartz crystals. One of these is doubly terminated.

Dims:2.0x1.1x0.9" (5.1x2.8x2.3 cm)

Wt: 2.4oz. (67g)

Yao Gang Xian Mine, Yizhang cty., Hunan prov., China

This specimen consists of an intergrown group of ferberite crystals. One side of the ferberite group is coated with a crust of rounded saddle-shaped dolomite crystals. Included in the dolomites are tiny crystals of chalcopyrite. The ferberites show rude terminations and excellent vertical striation. One ferberite crystal has been broken from the base of this specimen and is missing. This is the only damage of note to this specimen.

Dims:3.5x3.1x2.8" (8.9x7.9x7.1 cm)

Wt: 14.9oz. (421g)

Yao Gang Xian Mine,Yizhang cty., Hunan province, China

Growing from the side of a quartz crystal cluster is a large, tabular cluster of ferberite to 2.1" (5.3cm) in length. A vein of muscovite mica splits the ferberite crystal. Also present is pyrite.The quartz crystals have a coating on one side of an unidentified grayish mineral. One side of the ferberite crystal has been broken away; otherwise, this specimen shows relatively minor damage.

Dims:1.4x0.9x0.7" (3.6x2.3x1.8 cm)

Wt: 0.9oz. (25g)

Yao Gang Xian Mine, Yizhang cty., Hunan province, China

This is a wonderful thumbnail specimen of ferberite with muscovite and stannite. The ferberites show excellent terminations, and one of the crystals reaches 1.1" (2.8cm) in length. The stannite crystals are in the form of tetragonal dipyramids, and they reach 0.1" (0.3cm) in length. One of the ferberite crystals has been broken off near the termination-this is the only real damage to this specimen.

Dims:2.9x1.9x0.9" (7.4x4.8x2.3 cm)

Wt: 4.0oz. (113g)

Yao Gang Xian Mine, Yizhang cty., Hunan prov., China

Several large blades of ferberite rest on a bit of matrix material with quartz crystals in this specimen. The largest crystal measures 2.5" (6.4cm) in length, and has a good basal termination. Two of the ferberite blades are broken on this specimen, both on the display side.