CHALCOCITE
Specimen ccc-1

Dims: 1.0 x 0.9 x 0.9" (2.5 x 2.3 xc 2.3 cm)

Wt: 26.3 g w/ base

Bristol, Connecticut, U.S.A.

This thumbnail specimen consists of a cluster of many heavily-intergrown Chalcocite crystals. These crystals are in good-to-fair condition, showing several small areas of fresh breakage, and do not appear to exceed 0.3" (8 mm) in length. Their monoclinic prismatic form is not very good due to their intense intergrowth, but a few more or less individual crystals are present. All have a uniform dark gray coloration and a dull metallic luster. There is no host rock of any sort present, and the piece is hot-glued to a flat, square acrylic base.

Dims: 1.6 x 1.4 x 1.2" (4.1 x 3.6 x 3.0 cm)

Wt: 2.34 oz. (66.4 g)

Bristol, Connecticut, U.S.A.

Dozens of small Chalcocite crystals extend from the massive Chalcocite base of this specimen. These crystals do not appear to exceed 0.3" (8 mm) in length or width, and though they are in good condition, they are incomplete due to their intergrowth with the massive base. Their monoclinic form is good, though, where visible- edges are generally well-defined and faces are clean. All have a moderate gray color and a dull metallic luster, but damage surfaces on the piece show a deep, iridescent blue coloration and a brighter metallic luster. There are a few tiny calcite or cerussite crystals nestled in some crevices and some more massive material in a few spots.

Dims: 2.5 x 2.1 x 1.4" (6.4 x 5.2 x 3.6 cm)

Wt: 4.5 oz. (127 g)

Dzezkazgan, Dzezkazgan Region, Kazakhstan

At least 20 Chalcocite crystals rest on the gray base rock of this small cabinet specimen. These crystals are generally in good condition- a few are damaged or broken- and do not exceed 0.2" (5 mm) in length or diameter. Their orthorhombic form is rather heavily rounded, but one can still see some pseudohexagonal form and even evidence of some twinning. All have a black color and a dull, nearly submetallic luster. They are accompanied by several small quartz crystals that are in moderately good condition.

Dims: 3.8x1.5x2.1" (9.6x3.9x5.3 cm)

Wt: 14.1 oz. (401 g)

Flambeau Mine, 970 Ft. Level, Ladysmith, Rusk County, Wisconsin, USA

This hand specimen is all chalcocite which has uniformly tarnished to a metallic blue color with hints of purple in some areas. A variety of crystal forms are visible, including pseudo-hexagonal prismatic, pseudo-hexagonal tabular, and some crystals that almost look like metallic garnets. The irridescent blue tarnish is very appealing and make it easy to identify the areas of damage (the bottom and a few small areas along the top of the specimen), as these areas are not tarnished, and are a metallic gray color.

Dims: 1.75x1.25x1.15" (4.5x3.2x2.9 cm)

Wt: 4.05 oz. (114.5g)

Flambeau Mine, 970 Ft. Level, Ladysmith, Rusk County, Wisconsin, USA

This small specimen of chalcocite is a beautiful irridescent blue, changing to purple from certain angles. The crystal form of the chalcocite is typical with a rounded dome habit. The specimen is only damaged along its base and back, where it was separated from its host.

Dims: 1.10x0.83x0.63" (2.8x2.1x1.6cm)

Wt: 0.56oz. (15.5g)

Ladysmith, Rusk County, Wisconsin, USA

This is a fine chalcocite specimen from an old collection, and originally came from the Lucky Freddy Flambeau Mine. The specimen is a cluster of a dozen or so chalcocite crystals, all of which have a metallic purple color with irridescent hues of several other colors. The crystals are undamaged, and are typical of chalcocite in appearance.

Dims: 3.09x2.06x1.01" (7.84x5.22x2.56cm)

Wt: 4.85oz (137.2g)

Dzhezkazgan mine, Kazakhstan

On this specimen, the host rock is nearly covered on one surface with chalcocite crystals. They range in size up to 13mm, and have a dark gray color and metallic luster. The crystals are all distorted and show only strong hints of a hexagonal cross section, although many of them show characteristic blunt terminations and all show strong striations. There are other minerals present, both tiny quartz crystals, many golden chalcopyrite crystals, and several patches of tiny blue metallic crystals that look like bornite (they could, of course, be more chalcocite tarnished blue, but then why would the large crystals not have a blue tarnish?).

Dims: 1.44x1.20x0.71" (3.66x3.04x1.81cm)

Wt: 1.38oz (39.2g)

Flambeau mine, Rocket Pocket, Ladysmith, Rusk County, Wisconsin, USA

This is a beautiful specimen of irridescent chalcocite - the pictures can't do it justice. The individual crystals can be identified because each of them displays a different irridescent color, according to their orientation. These colors include blues, violets, purples, and golds. There is one crystal that is pseudo-hexagonal, looking a little bit like a shallow tetrahedron (upside down), but with the points replaced with short faces.

Dims: 1.43x0.93x0.49" (3.63x2.36x1.26cm)

Wt: 0.98oz (27.7g)

Flambeau mine, Rocket Pocket, Ladysmith, Rusk County, Wisconsin, USA

This is an incomplete cluster/crystal of chacocite. I suspect that the original specimen was fractured into two roughly equal parts, and this piece is essentially complete and undamaged except for the smooth, conchoidal fracture that terminates one side of the specimen. The original surfaces have the typicalmetallic luster and suface pattern due to thousands of crystal faces, all deeply striated, that provide the appealing texture of good chalcocite crystals. The fracture surface, however, is relatively smooth (but not perfectly so). All of the surfaces are irridescent in various hues. One side of the crystal is primarily blues/yellows/greens, while the opposite side primarily displays reds, violets, and purples. The fracture surface shows all colors, including brassy hues. There is a small area with a thin white coating that looks like calcite.

Dims: 1.03x0.75x0.72" (2.62x1.92x1.82cm)

Wt: 0.49oz (13.9g)

Flambeau mine, Rocket Pocket, Ladysmith, Rusk County, Wisconsin, USA

This small chalcocite specimen displays a number of excellent pseudohexagonal crystals, some prismatic and others tabular. It is clearly a cluster of multiple distinct crystals, although most of them have distorted shapes. All of the chalcocite displays an irridescent blue color which transitions to a purple hue at some angles. There are a few places which appear silvery with a bright metallic luster, and a loupe reveals that these appear to be fresh fracture surfaces with no tarnish. I am certain that these were attachment points for additional crystals which have broken away.