THE MINERAL MOLYBDENITE

  • Chemistry: MoS2, Molybdenum Sulfide
  • Class: Sulfides and Sulfosalts
  • Uses: major ore of molybdenum and as mineral specimens
  • Specimens
Molybdenite is a very soft metallic mineral. It can be easily confused with graphite, but not with many other minerals. Graphite has a darker black-silver color and a black-gray to brown-gray streak, whereas molybdenite has a bluish-silver color and streak. Unfortunately, the difference is so slight that it is recommended that the two minerals be seen side by side. Their respective streaks should also be observed side by side to appreciate the differences. If larger samples, free of host rock, are available, then the greater density of molybdenite can be used for identification.

Molybdenite's structure is composed of molybdenum ions sandwiched between layers of sulfur ions. The sulfur's layers are strongly bonded to the molybdenum, but are not strongly bonded to other sulfur layers, hence the softness and perfect cleavage. It is soft enough to leave a mark on paper and fingers. Its greasy feel is due to its extreme softness. Molybdenite or "Moly Ore" as it is sometimes called, is a very high luster mineral and can be an interesting mineral to add to a collection.

PHYSICAL CHARACTERISTICS:

  • Color is a silver metallic with a bluish cast.
  • Luster is metallic.
  • Transparency crystals are opaque.
  • Crystal System is hexagonal; 6/m2/m2/m
  • Crystal Habits: thin, platy hexagonal crystals terminated by pinacoidal faces, also as tapering six-sided pyramids that can be truncated by the pinacoids. Also massive, lamellar and in small grains in sulfide ore bodies and recrystallized marbles.
  • Cleavage is perfect in one direction, forming thin sheets.
  • Fracture is flaky.
  • Hardness is 1.5 - 2.
  • Specific Gravity is 4.7 to 4.8 (average for metallic minerals)
  • Streak is bluish gray.
  • Associated Minerals include pyrite, wolframite, chalcopyrite, quartz, fluorite, and scheelite.
  • Other Characteristics: thin cleavage sheets and crystals are flexible, but not elastic. It has a greasy feel and leaves marks on fingers.
  • Notable Occurrences Climax, Colorado; Cornwall, England, Raade, Norway; Wilberforce, Ontario and many other Canadian locallities.
  • Best Field Indicators are crystal habit, softness, cleavage, density, bluish streak and color.
MOLYBDENITE specimens:
(hover for more info)
MOLYBDENITE specimen mol-1
$ 30.00
Dims: 3-1/8" x 2" x 2"
Wt: 8.3 oz
Nevada, U.S.A.
Though rather small and thin, these "books" of Molybdenite are beautiful to look at and a pretty good price, to boot! The crystals are each approximately 5/8 x 1/2 inch in dimensions, and are very thin (1-2 mm), with the dull metallic luster reminiscent of graphite and galena. They rest on a base of massive quartz that has a light smattering of muscovite in a few places.
no photo
mol-1 ($ 30.00)
Nevada, U.S.A.
MOLYBDENITE specimen mol-3
$ 22.00
Dims: 2.6" x 2.3" x 1.7" (6.6 x 5.8 x 4.3 cm)
Wt: 4.72 oz.(133.9 g)
Nevada, U.S.A.
Two "books" of micaceous Molybdenite crystals are visible in a muscovite matrix on this specimen. One is completely exposed, whereas the other is halfway buried. The more exposed of the two has a hexagonal, almost diamond-shaped form, and the other's form is indefinite. Both have a dark gray color and metallic luster, and are opaque. The muscovite matrix that they are in is attached to a host rock that is made up of equal parts of massive quartz and a feldspar. There are one or two other tiny patches of this material, but they are only bits of crystals, and have no form.
no photo
mol-3 ($ 22.00)
Nevada, U.S.A.
MOLYBDENITE specimen mol-4
$ 20.00
Dims: 2.4" x 2.0" x 1.6" (6.1 x 5.1 x 4.1 cm)
Wt: 5.03 oz.(142.7 g)
Nevada, U.S.A.
The massive quartz host rock of this specimen acts as a bed for a single hexagonal "book" of Molybdenite. The book is in excellent condition, showing no human-induced damage, and has good hexagonal form and a flaky, micaceous tendency. It has a moderate gray coloration that resembles freshly-cleaved galena, and a similarly metallic luster. The book has dimensions of 0.5 x 0.4" (1.3 x 1.0 cm), and is probably no more than one or two millimeters thick. There are a few bits of muscovite accompanying the Molybdenite on the quartz host.
no photo
mol-4 ($ 20.00)
Nevada, U.S.A.
MOLYBDENITE specimen mol-5
$ 22.00
Dims: 3.0" x 1.8" x 1.7" (7.6 x 4.6 x 4.3 cm)
Wt: 3.73 oz.(105.9 g)
Nevada, U.S.A.
A hexagonal "book" of Molybdenite is half-exposed from the massive quartz host rock of this specimen. Although one of its edges is slightly bent flat, it is still in excellent condition, showing a definite hexagonal shape. It has a moderate gray color, a metallic luster, and a flaky consistency. From the visible portion, I have determined that the book measures about 0.6" (1.5 cm) in diameter and is no more than 2 mm thick. There are a few bits of muscovite visible in cracks in the quartz, which is colorless and partially transparent.
no photo
mol-5 ($ 22.00)
Nevada, U.S.A.
MOLYBDENITE specimen mol-6
$ 300.00
Dims: 2.8" x 2.3" x 1.6" (7.1 x 5.8 x 4.1 cm)
Wt: 11.3 oz. (320 g)
Wolfram Camp Mine, Northern Queensland, Australia
This hand specimen represents the largest single "book" of Molybdenite platelets that I have ever seen- it is huge! Other than a few small shards of quartz host rock, it is composed almost completely of Molybenite and is in excellent condition, showing only a small amount of damage. The book itself is rather warped, as it does not have a complete hexagonal shape and the platelets that constitute it diminish in size and are not aligned completely parallel to each other. The Molybdenite has the gray color, metallic luster, softness, and density that one expects from this mineral and shows what appears to be a substantial amount of rust-staining along its outer edges. It is one of my personal favorites of our newest additions.
no photo
mol-6 ($300.00)
Wolfram Camp Mine, Northern Queensland, Australia
MOLYBDENITE specimen mol-7
$ 27.00
Dims: 1.6" x 1.4" x 0.8" (4.1 x 3.6 x 2.0 cm)
Wt: 1.20 oz. (34.1 g)
Wolfram Camp Mine, Northern Queensland, Australia
This thumbnail specimen seems to be composed of one or two "books" of Molybenite that have been pressed together and considerably warped. It is difficult to detect a flat edge of one of the books, and their hexagonal outline is nonexistent. They do have the micaceous appearance, dark gray color, and dull metallic luster of Molybdenite, though, along with its characteristic density. There are a few tiny shards of broken quartz trapped in the folds of Molybdenite in one area, but there is no other host rock or foreign material. Likely the most impressive aspect of this specimen is the fact that it is nearly 100% Molybdenite by weight.
no photo
mol-7 ($ 27.00)
Wolfram Camp Mine, Northern Queensland, Australia
MOLYBDENITE specimen mol-8
$ 70.00
Dims: 2.6" x 2.4" x 1.5" (6.6 x 6.1 x 3.8 cm)
Wt: 5.37 oz. (152.4 g)
Wolfram Camp Mine, Northern Queensland, Australia
Several warped and incomplete Molybdenite "books" are intergrown on the white quartz host rock of this specimen. The largest of these books has dimensions of 1.3 x 0.7 x 0.2" (3.3 x 1.8 x 0.5 cm). Evidence of their hexagonal tabular form is almost nonexistent. The books show a moderately dark gray coloration and a metallic luster, and are opaque, of course. The quartz base on which they rest is mostly massive in habit, but a few small crystals emanate from one end of it, only one of which is complete.
no photo
mol-8 ($ 70.00)
Wolfram Camp Mine, Northern Queensland, Australia
MOLYBDENITE specimen mol-9
$ 28.00
Dims: 1.6 x 0.8 x 0.8" (4.1 x 2.0 x 2.0 cm)
Wt: 13.1 g
Childs-Alwinkle Mine, Copper Creek, Pinal County, Arizona, U.S.A.
This small thumbnail specimen consists of at least 12 hexagonal Molybdenite platelets that rest on a quartz-encrusted base rock. These platelets do not exceed 0.3" (8 mm) in diameter or 1 mm in thickness, and are in generally good condition, though a few of them show some damage in the form of bent crystals. Their form is generally fair, as many of the crystals do not show their characteristic hexagonal shape. All have a moderate gray color and a metallic luster, and are very soft and easy to bend. They rest on a bed of broken, rust-stained quartz crystals that coat a rusty, quartz-bearing base rock.
no photo
mol-9 ($ 28.00)
Childs-Alwinkle Mine, Copper Creek, Pinal County, Arizona, U.S.A.
MOLYBDENITE specimen mol-10
$ 75.00
Dims: 2.5 x 1.9 x 1.4" (6.4 x 4.8 x 3.6 cm)
Wt: 4.0 oz. (112.8 g)
Wolfram Camp Mine, Queensland, Australia
At least 8 "books" of hexagonal Molybdenite platelets rest on this small hand specimen. The largest of these measures 0.7" (1.8 cm) in diameter and 0.3" (8 mm) thick, and like the others, is somewhat warped and rounded in form. All but two of the books, however, have definable hexagonal tabular form and shape. The Molybdenite has a moderately dark gray coloration and a slightly dull metallic luster. There is a small amount of a massive, dull golden sulfide mineral accompanying the Molybdenite, but I do not know its composition. The quartz host rock on which all of this rests is massive and has a milky-white coloration and a dull waxy luster.
no photo
mol-10 ($ 75.00)
Wolfram Camp Mine, Queensland, Australia
MOLYBDENITE specimen mol-11
$ 35.00
Dims: 2.0 x 1.4 x 1.1" (5.1 x 3.6 x 2.8 cm)
Wt: 1.58 oz. (44.8 g)
Cleator, Arizona, U.S.A.
This hand specimen consists of two intersecting Molybdenite "books" that are partly embedded in a massive quartz base. The larger of the books has a diameter of about 0.7" (1.8 cm) and appears to have been cleaved, judging by the bright metallic luster of its exposed face. The other, smaller book rests behind the larger one and is mostly embedded in the quartz. Both have the standard gray color and dull metallic luster of the specie.
no photo
mol-11 ($ 35.00)
Cleator, Arizona, U.S.A.
MOLYBDENITE specimen mol-12
$ 30.00
Dims: 1.2 x 1.1 x 0.8" (3.0 x 2.8 x 2.0 cm)
Wt: 0.5 oz. (13 g)
Desmont Mine, Wilberforce, Ontario, Canada
At least 2 tabular Molybdenite crystals rest on the crystalline base of this thumbnail piece. The largest of thse measures 0.9" (2.3 cm) along its longest axis, and the other has a visible diameter of nearly 0.6" (1.5 cm). The larger crystal is much more exposed and is therefore not in very good condition - though not necessarily broken, it has been badly bent and warped so that one cannot define its hexagonal tabular form. The smaller is much better protected, and has a jagged but definable hexagonal outline. Both show the classic silver-gray color and metallic luster of the specie. The base is made up partly of massive white calcite and partly of a cluster of several intergrown, badly broken, dull green crystals that remind me of diopside or epidote. I am not sure what they are, but I am thinking one of the aforementioned.
no photo
mol-12 ($ 30.00)
Desmont Mine, Wilberforce, Ontario, Canada
MOLYBDENITE specimen mol-13
$ 65.00
Dims: 2.20x1.38x1.69" (5.6x3.5x4.3cm)
Wt: 2.29oz. (64.8g)
Glacier Peak, Cloudy Pass, Pluton, Snohomish County, Washington, USA
A single large crystal of molybdenite rests on this quartz and albite matrix. It is actually a book of thin plates, although the pages underneach are much smaller. The molybdenite is silver and opaque, with a bright metallic luster. There is also a small amount of muscovite present.
no photo
mol-13 ($ 65.00)
Glacier Peak, Cloudy Pass, Pluton, Snohomish County, Washington, USA
 

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