Molybdenite is a mineral of

molybdenum disulfide Molybdenum disulfide (or moly) is an inorganic compound composed of molybdenum and sulfur. Its chemical formula is . The compound is classified as a transition metal dichalcogenide. It is a silvery black solid that occurs as the mineral molybdenit ...

, Mo S₂. Similar in appearance and feel to graphite, molybdenite has a lubricating effect that is a consequence of its layered structure. The atomic structure consists of a sheet of

molybdenum Molybdenum is a chemical element with the symbol Mo and atomic number 42 which is located in period 5 and group 6. The name is from Neo-Latin ''molybdaenum'', which is based on Ancient Greek ', meaning lead, since its ores were confused with lea ...

atoms sandwiched between sheets of

sulfur Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...

atoms. The Mo-S bonds are strong, but the interaction between the sulfur atoms at the top and bottom of separate sandwich-like tri-layers is weak, resulting in easy slippage as well as cleavage planes. Molybdenite crystallizes in the hexagonal crystal system as the common

polytype In materials science, polymorphism describes the existence of a solid material in more than one form or crystal structure. Polymorphism is a form of isomerism. Any crystalline material can exhibit the phenomenon. Allotropy refers to polymorphism ...

2H and also in the trigonal system as the 3R polytype.

Description

Occurrence

Molybdenite occurs in high temperature hydrothermal ore deposits. Its associated minerals include pyrite, chalcopyrite, quartz, anhydrite, fluorite, and scheelite. Important deposits include the disseminated porphyry molybdenum deposits at Questa, New Mexico and the

Henderson Henderson may refer to: People *Henderson (surname), description of the surname, and a list of people with the surname *Clan Henderson, a Scottish clan Places Argentina *Henderson, Buenos Aires Australia *Henderson, Western Australia Canada *He ...

and

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mines in Colorado. Molybdenite also occurs in porphyry copper deposits of Arizona, Utah, and Mexico. Molybdenite Under normal and polarized light

Molybdenite Under normal and polarized light

The element rhenium is always present in molybdenite as a substitute for molybdenum, usually in the parts per million (ppm) range, but often up to 1–2%. High rhenium content results in a structural variety detectable by

X-ray diffraction X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles ...

techniques. Molybdenite ores are essentially the only source for rhenium. The presence of the radioactive isotope rhenium-187 and its daughter isotope

osmium Osmium (from Greek grc, ὀσμή, osme, smell, label=none) is a chemical element with the symbol Os and atomic number 76. It is a hard, brittle, bluish-white transition metal in the platinum group that is found as a trace element in alloys, mos ...

-187 provides a useful geochronologic dating technique.

Features

Molybdenite is extremely soft with a metallic luster, and is superficially almost identical to graphite, to the point where it is not possible to positively distinguish between the two minerals without scientific equipment. It marks paper in much the same way as graphite. Its distinguishing feature from graphite is its higher specific gravity, as well as its tendency to occur in a

matrix Matrix most commonly refers to: * ''The Matrix'' (franchise), an American media franchise ** ''The Matrix'', a 1999 science-fiction action film ** "The Matrix", a fictional setting, a virtual reality environment, within ''The Matrix'' (franchis ...

Uses

Molybdenite is an important ore of molybdenum, and is the most common source of the metal. While molybdenum is rare in the Earth's crust, molybdenite is relatively common and easy to process, and accounts for much of the metal's economic viability. Molybdenite is purified by froth flotation, and then oxidized to form soluble

molybdate In chemistry a molybdate is a compound containing an oxoanion with molybdenum in its highest oxidation state of 6. Molybdenum can form a very large range of such oxoanions which can be discrete structures or polymeric extended structures, althoug ...

. Reduction of ammonium molybdate yields pure molybdenum metal, which is used for fertilizer, as a catalyst, and in battery electrodes. By far the most common use of molybdenum is as an alloy with iron. Ferromolybdenum is an important component of high strength and corrosion-resistant steel.

Semiconductor

Multilayer molybdenite flakes are semiconductors with an indirect bandgap. In contrast, monolayer flakes have a direct gap. In the early years of the 20th century, molybdenite was used in some of the first crude semiconductor diodes, called cat's whisker detectors, which served as a

demodulator Demodulation is extracting the original information-bearing signal from a carrier wave. A demodulator is an electronic circuit (or computer program in a software-defined radio) that is used to recover the information content from the modulated ...

in early

crystal radio A crystal radio receiver, also called a crystal set, is a simple radio receiver, popular in the early days of radio. It uses only the power of the received radio signal to produce sound, needing no external power. It is named for its most impo ...

s. Monolayer molybdenite shows good

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and can be used to create small or low-voltage transistors. The transistors can detect and emit light and may have future use in optoelectronics.First light from molybdenite transistors. 19 Apr 2013
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References

External links

{{ores Sulfide minerals Molybdenum minerals Non-petroleum based lubricants Dry lubricants Trigonal minerals Minerals in space group 160 Hexagonal minerals Minerals in space group 194 Semiconductor materials