THE MINERAL TETRAHEDRITE
- Chemistry: Cu12Sb4S13, Copper Antimony Sulfide
- Class: Sulfides
- Group: Tetrahedrite
- Uses: ore of copper and as a minor ore of silver.
Specimens
Tetrahedrite is named for its common crystal form, the tetrahedron. The tetrahedron is an interesting isometric crystal form. It is obvious where the four three fold axes of the isometric system belong, as each one exits out of the crystal through each of the four identical "pyramidal" peaks. However the four fold axes are evidently missing. They aren't, they are just four fold rotoinversion axes. A four fold rotoinversion axis takes a face, rotates it 90 degrees (one fourth of a rotation) and then inverts it (up to down & right to left) through the crystal to the other side. Then it rotates it again 90 degrees and inverts it again through the crystal. Another rotoinversion operation and finally another (four in all) and the face is back, exactly where it started. The result is two faces on the "top" and two on the "bottom" of the crystal but in perpendicular orientation. The tetrahedral faces are in many instances modified by other crystal forms giving the crystals multiple facets while still retaining the basic tetrahedral shape.
Tetrahedrite is in an informal group of minerals called the "fahlerz" or "fahlores" group. The group is named for an old german miners word meaning "pale ore". Most members of the tetrahedrite group belong to this informal group.
Tetrahedrite can form interesting and handsome mineral specimens. Often it will contain a certain percentage of silver and be used as a minor ore. The multi-faceted tetrahedral crystals as well as the flat faced simple tetrahedral crystals can be very striking and a real pleasure for mineral collectors to own.
PHYSICAL CHARACTERISTICS:
- Color is black to steel gray to silver.
- Luster is metallic.
- Transparency crystals are opaque.
- Crystal System is isometric; bar 4 3m
- Crystal Habits of course include the tetrahedron sometimes modified by the dodecahedron and tristetrahedron. Twinning is occassionally seen. Also massive and granular.
- Cleavage is absent.
- Fracture is conchoidal.
- Hardness is 3 - 4+.
- Specific Gravity is approximately 4.6 - 5.1 (average for metallic minerals)
- Streak is black to brown.
- Associated Minerals are quartz, pyrite, galena, chalcopyrite and other sulfides.
- Other Characteristics: tarnishes to a greenish shade.
- Notable Occurances include Peru; Broken Hill, Australia; Mexico; Germany and others.
- Best Field Indicators are crystal habit, lack of cleavage and color.
 Amethyst Galleries' Mineral Gallery MINERALS |
TETRAHEDRITE specimen tet-1
$ 30.00
$ 30.00
Dims: 3" x 2" x 1"
Wt: 5.9 oz
Pachapaqui Mine, Ancash, Peru
The impressive feature of this specimen is not the form of the Tetrahedrite crystals, though there are several crystals that do have good tetrahedral shape. The thing that makes this piece stand out is the irridescent coating on those crystals, giving them beautiful green and violet-red hues on top of their dark grey color and metallic luster. These crystals lie atop a matrix that is composed of a variety of metal sulfides (Galena, Sphalerite, etc.) and a cluster of Quartz crystals that worm their way through gaps in the rock. The colors on this piece are very unusual and pretty.
tet-1 ($ 30.00)
Pachapaqui Mine, Ancash, Peru
TETRAHEDRITE specimen tet-2
$ 60.00
$ 60.00
Dims: 5" x 3" x 2-1/2"
Wt: 1 lb., 8 oz
Pachapaqui Mine, Ancash, Peru
This is one of our best Tetrahedrites; the surface of the specimen is littered with them, along with Quartz, Pyrite, and a smattering of Sphalerite. Most of the crystals are partially buried in the base rock, which is a mishmosh of various metal sulfides. The crystals are impressively sized, with some reaching 1/2 inch along the edges.
tet-2 ($ 60.00)
Pachapaqui Mine, Ancash, Peru
TETRAHEDRITE specimen tet-3
$ 73.00
$ 73.00
Dims: 3-5/8" x 2-1/4" x 2"
Wt: 12.1 oz
Pachapaqui Mine, Ancash, Peru
Though showing considerable damage, the Tetrahedrites on this specimen are quite beautiful, and very easy to see! The reason for their visibility is their large size, with the largest measuring almost 3/4" along an edge, and several measuring 1/2" or more. Damage is prevalent among the larger crystals, and is primarily limited to corners. There are dozens of smaller crystals(1/4" to 1/2" along an edge), however, that are in perfect condition, with surprisingly sharp edges and corners. All have a metallic color that is reminiscent of hematite in darkness, and all have excellent luster. There are crusts of tiny quartz crystals wedged in crevices where crystal edges meet, and some quartz-coated calcite. A few small bits of pyrite and irridescent chalcopyrite are present too, if one looks for them. The host rock is mainly composed of pyrite and Tetrahedrite.
tet-3 ($ 73.00)
Pachapaqui Mine, Ancash, Peru
TETRAHEDRITE specimen tet-4
$ 75.00
$ 75.00
Dims: 3.5" x 2.6" x 2.4"(8.9 x 6.6 x 6.1 cm)
Wt: 1 lb, 4.3 oz.(576 g.)
Huaron Mine, Ancash, Peru
Another "sulfide stew" specimen, this piece contains mostly Tetrahedrite by weight. The crystals do not exceed 1/2"(1.3 cm) long along an edge, and have an odd greenish tinge to them. Some of these also have a dusting of microscopic chalcopyrite crystals, making parts appear a deep golden color. Along with the hundreds of metallic tetrahedral crystals are patches covered with small (1/4"[6 mm] or less) quartz crystals that have perfect form and transparence. There is also a small amount of pyrite present in a form that looks like rounded cubes, but could be called pyritohedral. Finally, there are very large masses of sphalerite, most of which consist of shattered crystals. However, there is one that is undamaged. It is rather well-protected, as only one triangular crystal face is visible, but it is big, measuring over 0.6"(1.5 cm) along an edge(see the close-up image)! There are a few tiny pyramidal crystals erupting from the center of the larger one's face- it makes for a neat design.
tet-4 ($ 75.00)
Huaron Mine, Ancash, Peru
TETRAHEDRITE specimen tet-5
$ 30.00
$ 30.00
Dims: 2.1 x 1.7 x 0.8" (5.3 x 4.3 x 2.0 cm)
Wt: 3.29 oz. (93.3 g)
Pachapaque Mine, Ancash, Peru
This large thumbnail specimen consists of several Tetrahedrite crystals that are resting on a quartz-encrusted galena base. These crystals do not exceed 0.3" (8 mm) along any of their visible axes, and are generally in good condition, showing little damage. Most of these crystals do not exceed 0.1" (3 mm) along an edge, and these are all rather heavily intergrown. However, two of the crystals are integral, though partly intergrown with the galena, and have excellent tetragonal form. Their edges are sharp and their faces are clean, showing a moderate metallic luster. All have a moderate gray coloration that is slightly darker than the galena base. Besides the tiny quartz crystals that are scattered about, there are also several warped but generally intact chalcopyrites. The galena itself shows some noticeable crystal form, but it is heavily warped due to its intense intergrowth among both its own crystals and those that are crusted on top of it.
tet-5 ($ 30.00)
Pachapaque Mine, Ancash, Peru
TETRAHEDRITE specimen tet-6$ 385.00
Dims: 6.6 x 5.2 x 1.7" (16.8 x 13.2 x 4.3 cm)
Wt: 3 lbs., 2.3 oz. (1.424 kg)
Casa Pelca Mine, Ancash Department, Peru
This cabinet-size specimen consists mostly of Tetrahedrite by weight, in the form of the largest crystals of it that I have seen- one of them measures 1.8" (4.6 cm) in length, and most of the others are at least 1" (2.5 cm) long. Though most of the more exposed crystals are damaged, this damage is relatively minor. Their tetrahedral form is somewhat warped due to their considerable intergrowth but still discernable, with well-defined edges and relatively flat, smooth faces that possess the standard dull metallic luster. All have the moderately dark gray coloration that is common for this mineral, and are, of course, opaque.
tet-6 ($385.00)Casa Pelca Mine, Ancash Department, Peru
TETRAHEDRITE specimen tet-7
$ 30.00
$ 30.00
Dims: 4.1 x 2.6 x 1.3" (10.4 x 6.6 x 3.3 cm)
Wt: 10.46 oz. (296.5 g)
Pachapaque Mine, Ancash Department, Peru
Among the other metallic sulfides on this hand specimen rest scores of intergrown Tetrahedrite crystals. These crystals reach 0.4" (1.0 cm) in diameter and are generally in very good condition due to the fact that they are partly covered and protected by clusters and druses of tiny quartz crystals. Though heavily intergrown, their tetragonal form is evident and very well-defined, with sharp edges and clean faces. They possess the standard moderately dark gray coloration and metallic luster and are, of course, opaque. The Tetrahedrons are accompanied by intergrown crystals of pyrite, chalcopyrite and galena, which make up most of the base.
tet-7 ($ 30.00)
Pachapaque Mine, Ancash Department, Peru
TETRAHEDRITE specimen tet-8
$ 32.00
$ 32.00
Dims: 3.7 x 2.9 x 1.7" (9.4 x 7.4 x 4.3 cm)
Wt: 1 lb., 3.3 oz. (546 g)
Pachapaqui Mine, Ancash Department, Peru
At least 10 Tetragonite crystals rest among other metallic sulfide minerals on this specimen. These Tetrahedrite crystals are generally in very good condition, showing slight to moderate damage and little breakage, and do not exceed 0.3" (8 mm) along an edge. Their cube-based tetrahedral form is excellent, with well-defined edges and clean faces. All have a moderate gray color and a bright metallic luster. They are rather difficult to discern from their surroundings at times, as they are accompanied by large numbers of both intergrown bournonite and sphalerite crystals. However, their form is much more regular than that of the bournonite, and their color is paler and luster more metallic than that of the sphalerite. Many warped pyrites and a crust of hundreds of tiny quartz crystals are also present. These crystals rest on a base that is made up of all of the materials that are visible.
tet-8 ($ 32.00)
Pachapaqui Mine, Ancash Department, Peru
TETRAHEDRITE specimen tet-9
$ 30.00
$ 30.00
Dims: 1.8 x 1.6 x 1.3" (4.5 x 4.2 x 3.2 cm)
Wt: 1.3 oz. (36 g) w/ base
Casapalca Mine, Lima Department, Peru
A few well-formed Tetrahedrite crystals rest on this hand specimen. The largest of these crystals has visible dimensions of 0.6 x 0.4 x 0.3" (1.,6 x 1.0 x 0.9 cm), and like the others, is in good condition but is incomplete due to intergrowth and breakage caused by the mining of the piece. All have excellent tetrahedral form where intact and the standard dark gray color and dull metallic luster. They serve as the base for several white quartz crystals that are in good condition and have good form. The piece is hot-glued onto a flat acrylic base.
tet-9 ($ 30.00)
Casapalca Mine, Lima Department, Peru
TETRAHEDRITE specimen tet-11
$ 84.00
$ 84.00
Dims: 2.8 x 2.5 x 1.0" (7.2 x 6.3 x 2.5 cm)
Wt: 5.2 oz. (148 g)
Casapalca Mine, Peru
Dozens of intergrown Tetrahedrite crystals are intergrown with quartz crystals on this large hand specimen. These crystals measure up to 0.4" (1.0 cm) along an edge, and only the largest and most exposed crystals show any damage. Their isometric, tetrahedral form is excellent- most have very sharp edges and lightly striated faces. They have the standard dark, silvery-gray color and metallic luster. The quartz crystals that grow among them are in excellent condition and have excellent hexagonal prismatic form. They do not tend to exceed 0.3" (8 mm) in length and are transparent and extremely clear. All rest on a base of crystalline sphalerite.
tet-11 ($ 84.00)
Casapalca Mine, Peru
TETRAHEDRITE specimen tet-10
$ 35.00
$ 35.00
Dims: 2.1 x 2.0 x 1.2" (5.4 x 5.1 x 3.0 cm)
Wt: 3.7 oz. (106 g)
Mimosa Mine, Huancavelica Department, Peru
A crust of intergrown Tetrahedrite crystals makes up this hand specimen. The crystals therein reach diameters of 0.5" (1.3 cm) and are in very good condition, showing almost no damage. Their tetrahedral form is excellent, and all have the standard dark silvery-gray color and slightly dull metallic luster. Only a few small bits of other metallic sulfides are stuck to the bottom of the crust.
tet-10 ($ 35.00)
Mimosa Mine, Huancavelica Department, Peru
TETRAHEDRITE specimen tet-12
$ 120.00
$ 120.00
Dims: 4.5 x 2.5 x 2.2" (11.5 x 6.4 x 5.5 cm)
Wt: 7.5 oz. (213 g)
Casapalca, Peru
A few clusters of heavily-intergrown Tetrahedrite crystals are attached to the quartz base of this cabinet specimen. Though these crystals have been damaged and are incomplete, the damage occurred during their formation and is partly healed over- most are in very good condition. The largest of these appears to measure about 0.5" (1.3 cm) in diameter. Those that are complete and not heavily intergrown show excellent tetrahedral form, and all show the standard black-gray color and semi-metallic luster. They are accompanied by a layer of crystalline sphalerite that is sandwiched between them and the quartz base, veins of pyrite that run through the base, and scores of beautifully-formed quartz crystals that coat the rest of the base.
tet-12 ($120.00)
Casapalca, Peru
TETRAHEDRITE specimen tet-13
$ 60.00
$ 60.00
Dims: 2.0 x 1.8 x 1.4" (5.1 x 4.5 x 3.5 cm)
Wt: 3.2 oz. (91 g)
Casapalca, Peru
Dozens of heavily-intergrown Tetrahedrites help to make up this hand specimen. These crystals are in moderately good condition, as several are lightly damaged and a few are broken, and measure up to 0.5" (1.3 cm) along an edge. They have excellent tetragonal form and show the classic dark silvery-gray color and metallic luster of the specie. They are accompanied by several clusters of well-formed quartz crystals and rest on a sphalerite base that shows some surprisingly good crystal form of its own.
tet-13 ($ 60.00)
Casapalca, Peru
TETRAHEDRITE specimen tet-14
$ 45.00
$ 45.00
Dims:5.1x4.4x1.2" (13.0x11.2x3.0 cm)
Wt: 17.6oz. (498g)
Pachapaqui, Peru
This specimen is a slab chiseled from the wall of a hydrothermal vein. Numerous crystals of tetrahedrite to 0.5" (1.3cm) on edge are scattered over a matrix of galena, pyrite, quartz, manganocalcite, and bournonite. A few of the tetrahedrite crystals have minor damage to their tips, while others are undamaged. At least one of the quartz crystals is double terminated.
tet-14 ($ 45.00)
Pachapaqui, Peru
TETRAHEDRITE specimen tet-15
$ 35.00
$ 35.00
Dims:3.2x2.3x1.8" (8.1x5.8x4.6 cm)
Wt: 8.5oz. (240g)
Pachapaqui, Peru
This specimen was once part of a hydrothermal vein. Excellent crystals of tetrahedrite to 0.2" (0.5cm) on edge rest on a matrix of quartz, pyrite, sphalerite, and galena. At least one of these tetrahedrites shows penetration twinning. Two of the tetrahedrites show chipped corners; the remainder of the specimen is undamaged.
tet-15 ($ 35.00)
Pachapaqui, Peru
TETRAHEDRITE specimen tet-16
$ 300.00
$ 300.00
Dims: 5.7x5.7x2.6" (14.4x14.4x6.6cm)
Wt: 4 lbs. (2.0kg)
Casapalca Mine, Lima Department, Peru
This large tetrahedrite cabinet specimen is very good, with hundreds of intergrown tetrahedral crystals, although many other shapes are present as well. The base is composed of tetrahedrite, sphalerite, pyrite, and quartz, and there are dozens of fine prismatic quartz crystals on the surface, although the transparent crystals are nearly invisible against the jumble of tetrahedrite crystals. There is a lot of tetrahedrite here, and it does display well.
tet-16 ($300.00)
Casapalca Mine, Lima Department, Peru
TETRAHEDRITE specimen tet-17
$ 29.00
$ 29.00
Dims: 0.98x0.91x0.51" (2.5x2.3x1.3cm)
Wt: 0.64oz (18.0g)
Daly-Judge Mine, Summit County, Utah, USA
This large thumbnail specimen of tetrahedrite displays four recognizable tetrahedron crystals, plus several other fragments. All are intergrown, and all are incomplete, primarily due to that intergrowth. Only one crystal has all 4 faces visible. Still, the crystals are easily identified. The tetrahedrite is accompanied by numerous small cubes of pyrite, and a tiny bumpy blue area with the color of covellite, but it is likely just a blue tarnish on a pyrite fracture surface.
tet-17 ($ 29.00)
Daly-Judge Mine, Summit County, Utah, USA