THE MINERAL SKUTTERUDITE

  • Chemistry: CoAs3, Cobalt Arsenide
  • Class: Sulfides
  • Uses: a minor ore of Cobalt and Nickel
  • Specimens
Fine Skutterudite specimens have only recently had widespread distribution on the mineral market. Its pyrite-like crystal forms contrast with its silver color giving it a unique look that is a must for a serious mineral collector.

Skutterudite is the cobalt-rich end member of a series (Smaltite, Chloanthite, or Ferro-Arsenite) in which Nickel or Iron replaces part of the Cobalt. Enough nickel is usually present to make Skutterudite a significant ore of Nickel. The iron rich variety is rare.

PHYSICAL CHARACTERISTICS:

  • Color is tin white to silver.
  • Luster is metallic.
  • Transparency crystals are opaque.
  • Crystal System is isometric; bar 3 2/m
  • Crystal Habits include the octahedron often modified with cube faces and the pyritohedron; often in a massive form.
  • Cleavage is indistinct.
  • Fracture is conchoidal or uneven.
  • Hardness is 6.
  • Specific Gravity is approximately 6.5 - 6.8 (heavier than average for metallic minerals)
  • Streak is black.
  • Associated Minerals are erythrite and annabergite which form weathering crusts; also other cobalt and nickel sulfides and arsenides such as cobaltite.
  • Other Characteristics: sometimes irridescent.
  • Notable Occurances include Cobalt, Ontario; Skutterud, Norway; Franklin, New Jersey and other cobalt mines around the world.
  • Best Field Indicators are crystal habit, color, streak, lack of good cleavage and associations.
SKUTTERUDITE specimens:
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SKUTTERUDITE specimen sku-1
$ 23.00
Dims: 2" x 2" x 1"
Wt: 5.9 oz
Bou Azzer, Morocco
Beautiful, bright, metallic chunks of crystalline Skutterudite are peeking out of rhombohedral cleaved white Calcite on this excellent example. The crystals are incomplete- it basically looks like mass with small crystal faces covering parts of it, but we can't find any complete crystals of it. Its color is a bright, silvery metallic color, and its luster is very bright. I personally have a collector's gravitation towards this piece- the crystals boiling out of the Calcite just strike a chord in me. Besides, I think that the price is quite reasonable!
no photo
sku-1 ($ 23.00)
Bou Azzer, Morocco
SKUTTERUDITE specimen sku-2
$ 45.00
Dims: 2" x 1-1/2" x 1"
Wt: 4.8 oz
Bou Azzer, Morocco
This extremely dense mineral is a sight to see; the crystals' brightness and metallic luster exceed that of any sulfosalt mineral that I've seen before. The crystals are incomplete- it basically looks like mass with small crystal faces covering parts of it- but finding complete crystals of Skutterudite seems to imply divine intervention, so all we can do is pray. Meanwhile, close examination of the piece reveals small crystals of Calcite poking their schnozzes out here and there. This is really attractive stuff... check it out!
no photo
sku-2 ($ 45.00)
Bou Azzer, Morocco
SKUTTERUDITE specimen sku-4
$ 30.00
Dims: 2-1/2" x 2" x 1-1/2"
Wt: 7.5 oz
Bou Azzer, Morocco
These are likely to be the nicest "crystals" of Skutterudite that I have seen. Although incomplete, as if the crystals failed to completely form out of the Skutterudite host rock, the existing crystal faces are in near-perfect condition, showing definite pyritohedral form. Also nestled in with them are some crystal fragments of Calcite, which seem to supply a good growth base for the formation of crystals. For $30, I think this is a "keeper!"
no photo
sku-4 ($ 30.00)
Bou Azzer, Morocco
SKUTTERUDITE specimen sku-3
$ 20.00
Dims: 2-3/4" x 2-1/2" x 1-1/4"
Wt: 11.5 oz
Bou Azzer, Morocco
Very bright, metallic crystal faces adorn this uncommon specimen of Skutterudite. The faces are on the host rock, which is composed almost entirely of the cobalt arsenide mineral. They are primarily triangular in shape, as if octahedrons were attempting to form out of the matrix. There are small amounts of Calcite laced within the matrix, too. This specimen is at a bargain-basement price for the availability of such a mineral!
no photo
sku-3 ($ 20.00)
Bou Azzer, Morocco
SKUTTERUDITE specimen sku-5
$ 20.00
Dims: 2-1/4" x 2-1/8" x 3/4"
Wt: 3.9 oz
Bou Azzer, Morocco
A rather flat specimen, this piece is made up entirely of Skutterudite. Most of the visible material is massive in nature, but about 30% of the surface area is in a crystalline occurrence. None of the crystals are complete, with only a few faces on each crystal being visible, but the mineral's cubic form and related variations are evident under close examination. These faces have a silvery-white color and a very bright metallic luster, one of the brightest that I have seen in the mineral world. There is visible damage to some of the crystals, but most of these are at the edge of the cluster.
no photo
sku-5 ($ 20.00)
Bou Azzer, Morocco
SKUTTERUDITE specimen sku-6
$ 32.00
Dims: 1.6 x 1.5 x 0.7" (4.1 x 3.8 x 1.8 cm)
Wt: 2.07 oz. (58.7 g)
Bou Azzer, Morocco
This specimen consists of two crusts of crystalline Skutterudite that coat opposite ends of a pale pink host rock. The Skutterudite crystals that make up the crusts are heavily intergrown, and one of the crusts is too thin for actual crystals to have formed. The other crust is at least 0.3" (8 mm) thick, and contains incomplete crystals that are in good condition, though some obvious damage is present. All have what appears to be a good cubo-octahedral form, and the largest of these has visible dimensions of 0.2 x 0.2 x 0.1" (5 x 5 x 2 mm). Though incomplete, their form is very good- all have well-defined edges and clean faces that possess the standard metallic luster. They have the obligatory bright silvery-gray coloration and are opaque, of course. The pale pink host rock on which the crusts rest is made up of limestone.
no photo
sku-6 ($ 32.00)
Bou Azzer, Morocco
SKUTTERUDITE specimen sku-7
$ 60.00
Dims: 1.9 x 1.6 x 1.4" (4.8 x 4.1 x 3.6 cm)
Wt: 4.70 oz. (133.5 g)
Bou Azzer, Morocco
This large thumbnail specimen consists mostly of Skutterudite, though a small amount of white calcite is present. It consists of heavily intergrown crystals that are in moderately good condition and achieve diameters of 0.5" (1.3 cm) or more. Though heavily intergrown, one can still see evidence of an octahedral form with truncated tips. All have the bright silvery-gray color and metallic luster that are standard for this species. Judging by its weight, I would venture to say that there is very little calcite present on this piece.
no photo
sku-7 ($ 60.00)
Bou Azzer, Morocco
SKUTTERUDITE specimen sku-8
$ 140.00
Dims: 2.4 x 2.3 x 2.1" (6.1 x 5.8 x 5.3 cm)
Wt: 1 lb., 3.0 oz. (538 g)
Bou Azzer, Morocco
This heavy specimen consists of a large chunk of crystalline Skutterudite. Much of its surface is rough and uneven due to breakage, but a substantial portion is intact, showing the faces of many intergrown crystals. These crystals are not complete due to the fact that they formed right from the base, but many are at least 50% complete. The largest of these measure at least 0.4" (1.0 cm) in diamter, and all have excellent cubic form. They occur as cubes whose corners are truncated by such large faces that they are nearly cubo-octahedral. All have the bright, silvery-white color and very bright metallic luster that are standard for this mineral. A few bits of shapeless white calcite rest in crevices between crystals, and a black material coats a small portion of the surface- I am not sure, but I almost think that this black material is sphalerite.
no photo
sku-8 ($140.00)
Bou Azzer, Morocco
SKUTTERUDITE specimen sku-9
$ 45.00
Dims: 1.4 x 1.1 x 1.0" (3.6 x 2.8 x 2.5 cm)
Wt: 2.10 oz. (59.6 g)
Ahrbar, Morocco
This small piece consists of part of a cluster of many intergrown Skutterudite crystals. The piece shows much damage, but several crystals are intact. They measure up to 0.4" (1.0 cm) in diameter and are all heavily intergrown with each other, so that only a portion of each crystal is exposed. Their cube-based form is excellent, showing well-defined edges and clean faces, and they have the classic pale silvery-gray color and bright metallic luster of their species. There appears to be a small amount of sphalerite present, but no host rock.
no photo
sku-9 ($ 45.00)
Ahrbar, Morocco
SKUTTERUDITE specimen sku-10
$ 58.00
Dims: 2.6x1.8x1.6" (6.5x4.7x4.0cm)
Wt: 10.7 oz. (302.4g)
Bou Azzer, Morocco
This hand specimen is entirely skutterudite. It's intergrown jumble of crystals has one surface with excellent terminations and a bright, silvery color. The crystals have a variety of shapes, basically modified versios of several standard forms, and several of the crystals have garnet-like shapes, and some crystals appear to have 4 sided pyrimidal terminations. This is a good, typical specimen of skutterudite.
no photo
sku-10 ($ 58.00)
Bou Azzer, Morocco
SKUTTERUDITE specimen sku-11
$ 35.00
Dims: 2.04x1.73x1.31" (5.18x4.40x3.32cm)
Wt: 5.62oz (159g)
Bou Azzer, Morocco
This specimen is nearly all skutterudite, although much of it is massive (or at least grannular with an unknown cement). The top of the specimen has several large and well-formed crystals that look like typical skutterudite. They have a good silver color and metallic luster. Most of the crystal faces exhibit growth patterns in an appealing pattern or tiny new crystals scattered about.
no photo
sku-11 ($ 35.00)
Bou Azzer, Morocco
SKUTTERUDITE specimen sku-12
$ 40.00
Dims: 3.70x2.54x1.79" (9.39x6.46x4.55cm)
Wt: 20.11oz (570g)
Bou Azzer, Morocco
A typical specimen of skutterudite, this one is mostly massive (or more properly granular), intergrown with a fair amount of calcite and possibly another similar mineral. Along one section of the specimen, several dozen garnet-like crystals of skutterudite are exposed, and a few of these are very nice. These crystals have a bright metallic luster, and all of the skutterudite has a silvery gray color.
no photo
sku-12 ($ 40.00)
Bou Azzer, Morocco
SKUTTERUDITE specimen sku-13
$ 35.00
Dims: 4.27x2.24x1.92" (10.84x5.69x4.87cm)
Wt: 27.20oz (771g)
Bou Azzer, Morocco
This hand specimen is mostly skutterudite, although there is a significant amount of albite in veins through the rock. The skutterudite is generally in massive form, although there are hundreds of crystals (generally small) with excellent structure and terminations. They have a silvery-gray color and metallic luster. The largest crystal is about 10mm in length.
no photo
sku-13 ($ 35.00)
Bou Azzer, Morocco
SKUTTERUDITE specimen sku-14
$ 25.00
Dims: 1.96x1.94x1.47" (4.99x4.93x3.47cm)
Wt: 7.23oz (205g) ... Bou Azzer, Morocco
This specimen is mostly skutterudite, with a few patches of albite crystals on the surface and a vein of an unidentified black mineral along one side. While some of the skutterudite appears massive, most is crystalline, with the surface showing some excellent crystals. The largest crystals are about 1cm across, and all have the metallic silver color, bright metallic luster, and slightly uneven crystal faces typical of this mineral.
This specimen is mostly skutterudite, with a few patches of albite crystals on the surface and a vein of an unidentified black mineral along one side. While some of the skutterudite appears massive, most is crystalline, with the surface showing some excellent crystals. The largest crystals are about 1cm across, and all have the metallic silver color, bright metallic luster, and slightly uneven crystal faces typical of this mineral.
no photo
sku-14 ($ 25.00)
 

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