MOLYBDENITE

Molybdenite is a soft, opaque, lead-silvery-grey sulfide mineral with chemical formula MoS₂ (molybdenum disulfide), IMA symbol Mol, Strunz classification 2.EA.30, CAS number 1317-33-5, most commonly crystallising in the hexagonal system as the 2H polytype (space group P6₃/mmc) and less commonly as the trigonal 3R polytype (space group R3m), with Mohs hardness 1.0–1.5, specific gravity 4.62–4.73, and a perfect basal cleavage on {0001} that produces the characteristic greasy, soapy feel and strong lubrication effect arising from weak van der Waals interaction between adjacent sulfur atom layers in the S-Mo-S sandwich structure.
Molybdenite is the world's most important ore mineral of molybdenum and the essentially exclusive commercial source of rhenium; approximately 80% of mined molybdenite is processed into ferromolybdenum for high-strength, corrosion-resistant steel alloys, while the remainder yields molybdenum metal for catalysts, fertilisers, and battery electrodes, and rhenium (present as a Mo substituent at ppm to 1–2% concentrations) for superalloy production; molybdenite also functions as an exceptional high-temperature dry lubricant capable of withstanding temperatures exceeding 800°C, and as a direct bandgap monolayer semiconductor with applications in transistors and optoelectronics.
Molybdenite occurs in high-temperature hydrothermal deposits, porphyry copper-molybdenum systems, greisen deposits, and skarn mineralisation in association with pyrite, chalcopyrite, quartz, anhydrite, fluorite, and scheelite; first distinguished from graphite by Carl Wilhelm Scheele in 1778, and molybdenum first isolated as an element in 1781 by Peter Jacob Hjelm; it is not classified as hazardous under GHS for bulk natural mineral handling, though MoS₂ dust requires standard mineral dust respiratory precautions.

Chemical Formula: MoS₂
IMA Symbol: Mol
Strunz Classification: 2.EA.30
CAS Number: 1317-33-5
Molecular Weight: 160.07 g/mol

Synonyms: Molybdenum disulfide, Molybdenum(IV) sulfide, Molybdenite-2H, Molybdenite-3R, MoS₂, Molybdaena, Molybdenglanz, Molybdénite, Molibdenita, Molybdäneisenerz, IMA symbol Mol, Strunz 2.EA.30, CAS 1317-33-5

Composed of molybdenum and sulfur, Molybdenite has the chemical formula MoS₂.
The formula of Molybdenite corresponds to a molecular weight of approximately 160.07 g/mol.

Pure Molybdenite contains nearly 60% molybdenum and 40% sulfur by weight.
Within mineral classification systems, Molybdenite belongs to the metal sulfide group.

The common 2H form of Molybdenite crystallises in the hexagonal crystal system.
A less common 3R polytype gives Molybdenite a trigonal crystal arrangement.

Each structural layer of Molybdenite contains molybdenum atoms positioned between two sulfur sheets.
Strong molybdenum–sulfur bonds hold the individual layers of Molybdenite together.

Weak interactions between adjacent sulfur surfaces allow the layers of Molybdenite to slide easily.
This layered structure gives Molybdenite excellent lubricating behaviour and perfect basal cleavage.

Lead-grey, silver-grey, and nearly black colours commonly occur in Molybdenite.
A bright metallic lustre gives crystalline Molybdenite a distinctive reflective appearance.

With a Mohs hardness of approximately 1–1.5, Molybdenite ranks among the softest metallic minerals.
Thin flakes of Molybdenite remain flexible but do not return elastically to their original shape.

A greasy feel and the ability to mark paper make Molybdenite superficially similar to graphite.
Higher density and a bluish-grey streak help distinguish Molybdenite from graphite.

Hydrothermal veins associated with granitic rocks commonly contain Molybdenite.
Large porphyry molybdenum and porphyry copper deposits provide important economic sources of Molybdenite.

Quartz, pyrite, chalcopyrite, fluorite, scheelite, and anhydrite may occur alongside Molybdenite.
High-temperature mineralising fluids can deposit Molybdenite in veins, fractures, and disseminated ore zones.

As the principal ore mineral of molybdenum, Molybdenite supplies most of the world’s primary molybdenum.
Froth flotation concentrates Molybdenite from finely ground molybdenum and copper ores.

Differences in surface properties allow flotation systems to separate Molybdenite from many associated minerals.
Repeated cleaning stages can produce high-grade Molybdenite concentrate suitable for further processing.

Oxidative roasting converts concentrated Molybdenite into technical-grade molybdenum trioxide.
Sulfur dioxide forms as a gaseous product during the roasting of Molybdenite.

Chemical processing can convert roasted Molybdenite products into ammonium molybdate and other molybdenum compounds.
Further reduction of products derived from Molybdenite can produce high-purity molybdenum metal.

Ferromolybdenum production relies heavily on molybdenum obtained from Molybdenite.
Steels containing molybdenum derived from Molybdenite can show improved strength, hardness, and corrosion resistance.

Small amounts of rhenium frequently substitute for molybdenum within the structure of Molybdenite.
Processing rhenium-bearing Molybdenite concentrates provides one of the main commercial sources of rhenium.

The rhenium–osmium isotope system in Molybdenite allows geologists to determine the age of mineralisation.
Because Molybdenite incorporates rhenium but little initial osmium, the mineral is particularly useful for geochronology.

As a dry solid lubricant, Molybdenite reduces friction between moving surfaces.
Vacuum, high load, and elevated-temperature systems can benefit from the lubricating performance of Molybdenite.

Lubricating greases, oils, pastes, and bonded coatings may contain finely divided Molybdenite.
The layered particles of Molybdenite can form a low-shear film on metal surfaces.

Metalworking and forming operations use Molybdenite to reduce wear and prevent surface seizure.
Composite materials can incorporate Molybdenite to provide self-lubricating properties.

Catalyst systems derived from Molybdenite support hydrodesulfurisation reactions in petroleum refining.
The sulfur-rich edges of Molybdenite-based catalysts provide active sites for selected chemical transformations.

Bulk Molybdenite behaves as a semiconductor with an indirect electronic band gap.
A single atomic layer gives Molybdenite a direct band gap and different optical behaviour.

Atomically thin Molybdenite can function as the active channel in field-effect transistors.
Photodetectors, sensors, and optoelectronic devices are important research applications for Molybdenite.

Flexible electronic systems can benefit from the small thickness and mechanical flexibility of Molybdenite layers.
Low-voltage and highly miniaturised devices continue to drive research on Molybdenite.

Energy-storage studies evaluate Molybdenite for use in battery electrodes and supercapacitor materials.
The layered structure allows Molybdenite to interact with ions during electrochemical cycling.

Synthetic production methods can prepare Molybdenite with controlled particle size, layer number, and surface area.
Hydrothermal synthesis, chemical vapour deposition, and sulfurisation processes can generate synthetic Molybdenite.

Heating Molybdenite in air gradually converts the mineral into molybdenum oxide and sulfur-containing gases.
Temperature and oxygen availability strongly influence the oxidation behaviour of Molybdenite.

Uses of Molybdenite:
Molybdenite is the world's primary ore of molybdenum; approximately 80% of production is converted to ferromolybdenum (FeMo, ~60–70% Mo) by oxidative roasting to MoO₃ followed by aluminothermic or carbothermic reduction, with ferromolybdenum then alloyed into high-strength low-alloy (HSLA) steels, stainless steels, tool steels, and superalloys to increase tensile strength, yield strength, hardness, and resistance to high-temperature creep and corrosion.
Molybdenite and its derivative molybdenum disulfide (MoS₂ powder and paste) are widely used as high-performance dry lubricants and solid lubricant additives in greases, oils, and pastes for automotive chassis fittings, suspension systems (tie rods, ball joints, steering knuckles), driveline U-joints, pinion gear assemblies, and industrial machinery operating at temperatures up to 800°C in vacuum or inert atmospheres where liquid lubricants fail.
Molybdenite is the essentially exclusive commercial source of rhenium, which is present as a structural substitute for molybdenum at concentrations from ppm to 1–2% in molybdenite ore; rhenium recovered from MoO₃ calcines during molybdenite processing is used in nickel-based superalloys for jet turbine blades, as a catalyst in petroleum reforming, and in high-temperature thermocouples and filaments.
Molybdenite-derived molybdenum trioxide and ammonium molybdate are used as selective oxidation and hydrodesulfurisation (HDS) catalysts in petroleum refining (removing sulfur from fuels to meet emission standards), and as catalysts in the production of formaldehyde and acrylonitrile.
Molybdenite ore and MoS₂ are used as trace element bioavailable sources of molybdenum in fertilisers for legume crops, where molybdenum is an essential cofactor for nitrogenase (nitrogen fixation) and nitrate reductase enzymes in the nitrogen cycle.
Monolayer and few-layer MoS₂ derived from molybdenite is a direct-bandgap semiconductor (bandgap ~1.8 eV for monolayer, indirect ~1.2 eV for bulk) with high charge carrier mobility (~200 cm²/V·s), used in field-effect transistors (FET), photodetectors, light-emitting devices, and solar cells in next-generation flexible and ultra-thin optoelectronic devices.
Molybdenite Re–Os isotope geochronology (exploiting the radioactive decay of ¹⁸⁷Re to ¹⁸⁷Os) is a standard technique for dating molybdenum ore deposit formation ages; molybdenite trace element geochemistry (LA-ICP-MS) is used to fingerprint ore deposit types and constrain ore-forming fluid sources, with Re content >100 ppm indicating mantle-dominated source and <10 ppm indicating crust-dominated source.

Benefits and Advantages of Molybdenite:
The layered S-Mo-S van der Waals crystal structure of molybdenite gives it uniquely low friction coefficients (μ = 0.03–0.06 in vacuum) that are maintained from cryogenic temperatures to over 800°C and in high-vacuum environments where no liquid lubricant can function, making it irreplaceable in aerospace, nuclear, and extreme environment tribological applications.
Molybdenite is the only commercially viable source of both molybdenum and rhenium from a single ore mineral — the rhenium co-product, recovered at no additional mining cost from molybdenite processing, supplies over 80% of the world's rhenium production, making molybdenite ore uniquely dual-commodity.
The 2H polytype of molybdenite was one of the first monolayer materials to demonstrate a direct bandgap transition upon thinning to a single S-Mo-S sandwich (~6.5 Å), making it a foundational material in two-dimensional (2D) electronics research alongside graphene and hexagonal boron nitride.
Molybdenite is amenable to straightforward processing by froth flotation (exploiting its natural hydrophobicity from the sulfur-terminated van der Waals surface) and oxidative roasting to MoO₃, providing a direct and economical hydrometallurgical route to molybdenum metal and compounds without smelting.

Features of Molybdenite:
Molybdenite occurs as thin, platy hexagonal crystals slightly dished in the centre, tapering six-sided pyramids, lamellar foliated masses, or disseminated flakes and grains in sulfide ore bodies; colour is black, lead-silvery grey to bluish-grey; luster is metallic; streak is bluish-grey to grayish-black; lamellae are flexible but not elastic; the mineral marks paper like graphite but is distinguished by higher specific gravity (4.62–4.73 vs graphite ~2.1) and its occurrence in a mineral matrix.
Molybdenite is nearly opaque but translucent in thin flakes; it has a greasy, soapy feel caused by the weak van der Waals bonds between sulfur layers; it is infusible (decomposes at ~1185°C rather than melting); it is sectile under a knife blade (peels without fracture); very strong pleochroism is observed in reflected light microscopy; it does not exhibit fluorescence.
The atomic structure consists of sheets of Mo atoms in trigonal prismatic coordination between two layers of S atoms (S-Mo-S trilayer); the Mo-S bonds within each sandwich are strong covalent-ionic bonds, while adjacent trilayers are held only by weak van der Waals forces, producing perfect basal cleavage on {0001}, easy sliding, and the lubricating effect; unit cell 2H: a = 3.16 Å, c = 12.3 Å, Z = 2; unit cell 3R: a = 3.16 Å, c = 18.33 Å, Z = 3.
Theoretical chemical composition: Mo 59.94%, S 40.06% by weight; trace elements systematically present include Re (ppm to 2%), W, Bi, Pb, Te, Ag, Cu, Au, Zn, Sn, Se, and Co; the 3R polytype typically accommodates higher Re, W, Sn, and Bi contents than the 2H polytype.

Mineralogical and Chemical Properties of Molybdenite:
Molybdenite has molecular formula MoS₂, molar mass 160.07 g/mol, CAS 1317-33-5; it belongs to the sulfide mineral class (molybdenite group) and to the two-dimensional structural mineral category in mineral material science; it is a simple sulfide in which Mo is in the +4 oxidation state and each Mo is tetrahedrally/trigonal-prismatically coordinated by six S atoms in two layers; SMILES [Mo](=S)=S, InChI=1S/Mo.2S, InChIKey CWQXQMHSOZUFNT-UHFFFAOYSA-N; PubChem CID 14823.
Molybdenite crystallises in two polytypes: the common 2H polytype (hexagonal, P6₃/mmc, dihexagonal dipyramidal class 6/mmm) and the rare 3R polytype (trigonal, R3m, ditrigonal pyramidal class 3m); the structural difference lies in the stacking sequence of S-Mo-S layers — ABAB stacking in 2H vs ABCABC in 3R; high rhenium content favours 3R formation and is detectable by X-ray diffraction.
Molybdenite is insoluble in dilute HCl and H₂SO₄ but dissolves in concentrated HNO₃ and aqua regia; Carl Wilhelm Scheele (1778) first distinguished molybdenite from graphite by demonstrating its solubility in acid; bulk MoS₂ is thermally stable to ~1185°C, at which temperature it decomposes rather than melting; oxidative roasting at 400–600°C in air converts MoS₂ to MoO₃ (technical molybdenite processing step).
The Re–Os isotope system in molybdenite (¹⁸⁷Re → ¹⁸⁷Os, t½ = 4.16×10¹⁰ years) provides a direct geochronometer for ore deposit formation; molybdenite is particularly useful because it incorporates Re but essentially no common Os at formation, making it ideal for isochron dating without common Os correction.

Occurrence and Production of Molybdenite:
Molybdenite occurs in high-temperature hydrothermal and magmatic environments: porphyry Cu-Mo deposits (the dominant ore type, hosted in granodioritic to monzonitic porphyries), greisen Mo-W-Sn deposits (related to fertile S-type granites), skarn deposits at granite–carbonate contacts, and quartz vein systems; associated minerals include pyrite, chalcopyrite, quartz, anhydrite, fluorite, scheelite, cassiterite, wolframite, and feldspars.
Major world-class molybdenite deposits include Climax Mine (Colorado, USA; world's largest single Mo deposit), Henderson Mine (Colorado, USA), Questa Mine (New Mexico, USA), Bingham Canyon (Utah, USA, porphyry Cu-Mo), El Teniente (Chile, world's largest underground copper mine with significant Mo), Kennecott (Alaska, USA), Jiangxi and Henan provinces (China; world's largest Mo producer), and Sar Cheshmeh (Iran); global Mo production is approximately 250,000 tonnes per year.
Molybdenite is processed commercially by froth flotation (exploiting the naturally hydrophobic van der Waals sulfur surface), yielding a molybdenite concentrate; the concentrate is oxidatively roasted in multiple-hearth or rotary kilns at 500–600°C to produce technical MoO₃ (molybdic oxide), from which ferromolybdenum (aluminothermic process), ammonium molybdate (leaching), rhenium (from flue gas scrubbing), and molybdenum metal (hydrogen reduction of MoO₃) are obtained.

Molybdenite Material Safety Data Sheet (MSDS):

Handling of Molybdenite:
Natural molybdenite mineral and MoS₂ powder may generate respirable mineral dust containing molybdenum disulfide during crushing, grinding, and processing; inhalation of fine MoS₂ dust should be avoided, and adequate ventilation or respiratory protection used in dusty operations.
MoS₂ is not classified as acutely toxic under GHS for bulk natural mineral; however, molybdenum compounds in general should be handled with care, as chronic high-level molybdenum exposure may cause molybdenosis; use standard mineral dust handling precautions.

Molybdenite SDS:

Stability and Reactivity of Molybdenite:

Chemical stability:
Molybdenite is chemically stable under ambient conditions; insoluble in dilute acids and water under normal conditions.
Molybdenite oxidises on heating in air above ~400°C to form MoO₃ (molybdic oxide), which is water-soluble and represents a change in hazard profile.

Reactivity:
Molybdenite reacts with concentrated nitric acid and aqua regia to dissolve.
At temperatures above 400–600°C in air, MoS₂ is oxidised to MoO₃ with evolution of SO₂ (sulfur dioxide) — both products require attention in roasting operations.

Conditions to avoid:
Oxidising environments at elevated temperatures (>400°C in air — oxidation to MoO₃ + SO₂).
Concentrated oxidising acids (HNO₃, aqua regia).
Fine dust generation (respiratory hazard).

Incompatible materials:
Concentrated oxidising acids.
Strong oxidising agents at elevated temperature.
Fluorine and other reactive halogens.

Hazardous decomposition products:
Sulfur dioxide (SO₂) upon oxidative roasting or combustion.
Molybdenum trioxide (MoO₃) fume upon high-temperature oxidation — MoO₃ is irritating to eyes, skin, and respiratory tract.

Handling and Storage of Molybdenite:

Handling:
Minimise dust generation during crushing, grinding, and handling of MoS₂ mineral and powder.
Provide local exhaust ventilation in dusty operations.
Wear appropriate respiratory protection where dust exceeds OEL for molybdenum (Mo OEL: 10 mg/m³ TWA as Mo for insoluble compounds per ACGIH; 5 mg/m³ respirable fraction).
Wash hands after handling; do not eat, drink, or smoke in dusty work areas.

Storage:
Store natural specimens and MoS₂ powder in dry conditions in closed containers.
No special temperature requirements for ambient storage.
Keep away from concentrated oxidising acids.

First Aid Measures for Molybdenite:

Inhalation:
Move the affected person to fresh air; if respiratory irritation persists, consult a physician.
For chronic occupational dust exposure, periodic lung function and urinary molybdenum monitoring is recommended.

Skin contact:
Wash with water; MoS₂ may stain skin grey/black but is not a primary skin irritant.

Eye contact:
Rinse with water for several minutes; consult a physician if irritation persists.

Ingestion:
Rinse the mouth with water; MoS₂ is of low acute oral toxicity; consult a physician if large quantities are ingested.

Firefighting Measures for Molybdenite:

Suitable extinguishing media:
Molybdenite is a non-combustible mineral; use extinguishing media appropriate to surrounding fire.

Specific hazards:
At very high temperatures in air, MoS₂ may oxidise to MoO₃ and release SO₂; both are respiratory irritants.
MoO₃ fume is particularly irritating and may form in roasting or smelting operations.

Protective equipment for firefighters:
SCBA and full protective clothing where SO₂ and MoO₃ fume may be present.

Accidental Release Measures for Molybdenite:

Personal precautions:
Prevent fine MoS₂ powder dust generation; wear respiratory protection if powder is released.

Environmental precautions:
Molybdenum is an essential trace element at low concentrations; at high concentrations Mo may be harmful to aquatic organisms; prevent large quantities from entering water courses.

Clean-up methods:
Collect mechanically or wet-sweep to prevent dust; dispose in accordance with applicable regulations.

Exposure Controls / Personal Protective Equipment for Molybdenite:

Engineering controls:
Local exhaust ventilation in grinding and processing areas; wet methods preferred to control Mo dust.

Eye protection:
Safety glasses or goggles during handling of crushed mineral or powder.

Hand protection:
General purpose gloves for abrasion protection; nitrile gloves for fine powder handling.

Respiratory protection:
P95 (US) or P2 (EU EN 143) particle filter for dusty operations; OV/P100 for operations with Mo oxide fume.

Molybdenite Identifiers:
IMA Symbol: Mol
Strunz Classification: 2.EA.30
CAS Number (MoS₂): 1317-33-5
Chemical Formula: MoS₂
Molecular Weight: 160.07 g/mol
PubChem CID: 14823
InChI: InChI=1S/Mo.2S
InChIKey: CWQXQMHSOZUFNT-UHFFFAOYSA-N
SMILES: [Mo](=S)=S
Crystal System: Hexagonal (2H polytype); Trigonal (3R polytype)
Crystal Class: 2H: Dihexagonal dipyramidal (6/mmm); 3R: Ditrigonal pyramidal (3m)
Space Group: 2H: P6₃/mmc; 3R: R3m
Unit Cell 2H: a = 3.16 Å, c = 12.3 Å, Z = 2
Unit Cell 3R: a = 3.16 Å, c = 18.33 Å, Z = 3
Composition: Mo 59.94%, S 40.06% (theoretical)
Colour: Black; lead-silvery grey; bluish-grey
Crystal Habit: Platy hexagonal; lamellar; massive; granular
Cleavage: {0001} perfect
Tenacity: Lamellae flexible, not elastic; sectile
Mohs Hardness: 1.0–1.5
Luster: Metallic
Streak: Bluish-grey to grayish-black
Diaphaneity: Nearly opaque; translucent in thin flakes
Specific Gravity: 4.62–4.73
Pleochroism: Very strong (reflected light)
Fusibility: Infusible (decomposes at ~1185°C)
Feel: Distinctly greasy / soapy
Fluorescence: None
GHS Classification: Not classified as hazardous (bulk natural mineral); Mo OEL: 10 mg/m³ TWA (ACGIH, insoluble compounds)
Mineral Class: Sulfide (molybdenite group)
Deposit Types: Porphyry Cu-Mo; greisen Mo-W-Sn; skarn; quartz vein

Properties of Molybdenite:
Mineral class: Sulfide
Chemical formula: MoS₂
Molecular weight: 160.07 g/mol
Composition: Mo 59.94%, S 40.06%
Crystal system: Hexagonal (2H); Trigonal (3R)
Colour: Black; lead-silvery grey; bluish-grey
Crystal habit: Platy hexagonal crystals; lamellar; massive; granular
Cleavage: {0001} perfect
Tenacity: Flexible lamellae, sectile
Mohs hardness: 1.0–1.5
Luster: Metallic
Streak: Bluish-grey to grayish-black
Transparency: Opaque (thin flakes translucent)
Specific gravity: 4.62–4.73
Pleochroism: Very strong
Feel: Greasy, soapy
Decomposition temperature: ~1185°C
GHS Classification: Not classified (bulk mineral)
Storage: Dry, closed containers

Molybdenite Properties — Specifications:
Product name: Molybdenite (MoS₂)
IMA Symbol: Mol
Chemical Formula: MoS₂
Molecular Weight: 160.07 g/mol
Theoretical Mo content: 59.94%
Theoretical S content: 40.06%
Specific gravity: 4.62–4.73
Mohs hardness: 1.0–1.5
Crystal system: Hexagonal (2H)/Trigonal (3R)
Available grades: Ore mineral (run-of-mine); molybdenite concentrate (froth flotation); technical MoO₃ (oxidative roasting); pure MoS₂ powder (lubricant/semiconductor grade)
Storage: Dry, closed containers; away from oxidising acids and high-temperature oxidising environments
Format: Lump ore; concentrate; fine powder (lubricant grade)
Documents: Product data sheet and CoA available on request

Names of Molybdenite:
Molybdenite
Molybdenum disulfide
Molybdenum(IV) sulfide
Molybdenite-2H
Molybdenite-3R
MoS₂
Molybdaena
Molybdenglanz
Molybdénite
Molibdenita
Molybdäneisenerz
IMA symbol Mol
Strunz 2.EA.30
CAS 1317-33-5
PubChem CID 14823