How to Identify Molybdenite: Properties & Lookalikes

Bluish-silver molybdenite flakes along pale veins in a granite specimen — Molybdenite flakes in granitePhoto: Nessa Eull · CC0 1.0 · Wikimedia Commons

Classification

What is molybdenite?

Molybdenite is molybdenum disulfide, MoS₂. Rhenium may substitute in small amounts, but appearance cannot determine trace-element content or ore grade.

Appearance

What does molybdenite look like?

Molybdenite forms platy hexagonal crystals, foliated masses, rosettes, and disseminated flakes. Fresh surfaces are metallic bluish gray and may leave a gray to greenish-gray mark.

Thin flakes bend but do not spring back. Oxidation can dull surfaces or produce yellowish secondary molybdenum minerals.

Field tests

Identification tests

Begin with observation and use the least destructive test first. Results can change with weathering, mixtures, coatings, and grain size. Review the step-by-step field-test methods before altering an unfamiliar specimen.

Hardness

About 1 to 1.5

Scratched very easily, similar to graphite.

Streak or mark

Gray to greenish gray

Often lighter and greener than graphite’s black mark.

Density

High; specific gravity about 4.6 to 5.1

A compact piece feels much heavier than graphite.

Cleavage and tenacity

Perfect basal cleavage; flexible, nonelastic flakes

Confirms a soft layered mineral but not molybdenite alone.

Useful procedures: Mohs hardness test · Mineral streak test · Specific gravity and density test · Cleavage versus fracture

Comparison

Common lookalikes

Graphite

Darker, much lighter in weight, and commonly leaves a blacker mark.

Galena

Brittle, cubically cleaved, and lacks flexible platy flakes.

Biotite

Usually brown to black, elastic in thin sheets, and less metallic.

Geologic origin

How does it form?

Molybdenite commonly crystallizes from hydrothermal fluids in porphyry molybdenum and porphyry copper systems, quartz veins, greisens, and skarns.

It may occur with quartz, feldspar, pyrite, chalcopyrite, fluorite, scheelite, and alteration minerals. Sparse flakes do not establish economic grade.

Where it occurs

Geologic setting and occurrence

Molybdenite is widespread in certain granitic hydrothermal systems but is rarely abundant in an ordinary hand sample. Weathering can remove or alter exposed flakes.

Field identification should be confirmed where resource, environmental, or processing decisions depend on it.

Human use

Uses and significance

Molybdenite is the principal source of molybdenum, used in alloy steels, stainless steels, catalysts, pigments, lubricants, and high-temperature applications.

Safety and limits

Field notes

Avoid grinding sulfide-bearing material or inhaling dust.
A few visible flakes do not establish a mineable molybdenum deposit.
Do not enter adits, trenches, or unstable exploration workings.

This guide supports preliminary field identification, not a laboratory determination, appraisal, hazard assessment, or statement of ownership or collecting permission. Verify land status and local rules before handling or collecting material.

Source basis

Authoritative sources

LithoMap wrote this guide in original language using the scientific concepts and physical-property standards supported by these sources.

Molybdenum Statistics and Information U.S. Geological Survey
Minerals and their physical properties U.S. National Park Service
Mohs Hardness Scale U.S. National Park Service
Natural Gemstones: Mineral Gemstones U.S. Geological Survey

Editorial review: September 17, 2026.

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