Molybdenite: the ore of molybdenum, not to be confused with graphite

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Molybdenite is a very soft, silvery grey molybdenum sulphide that stains the fingers. Mineralogy, industrial uses, safety precautions, care and buying tips.

Key points

Colour	lead grey to silvery grey, metallic lustre
Mineral family	molybdenum sulphide, MoS2
Crystal system	hexagonal (the most common variety, known as 2H); trigonal for the 3R variety
Hardness (Mohs)	1 to 1.5 (like talc; it can be scratched with a fingernail)
Density	about 4.7
Streak	bluish grey; stains paper and fingers
Cleavage	perfect, in flexible but non-elastic flakes
Known deposits	Colorado (Climax, Henderson), New Mexico (Questa), Arizona, Utah, Mexico, Quebec
Industrial use	main ore of molybdenum and almost the only source of rhenium
Precautions	see the safety box below: wash your hands, no elixirs, no dust

What is molybdenite?

Molybdenite is a molybdenum sulphide (MoS2). It forms small flakes or masses of silvery grey spangles, shiny like metal, that split into flexible sheets. It is extremely soft (1 to 1.5 on the Mohs scale, like talc), greasy to the touch, and it leaves bluish grey marks on the fingers and on paper.

Its name comes from the Greek molybdos, “lead”: it was once taken for lead or for graphite. In 1778 the Swedish chemist Carl Wilhelm Scheele showed that it was a separate substance, and shortly afterwards his colleague Peter Jacob Hjelm isolated the metal molybdenum from this ore (1781 or 1782 depending on the source). See also our page what is a mineral?.

What is molybdenite used for?

It is first and foremost an ore: molybdenite is the most common source of molybdenum, a metal added to steel to make it more resistant to heat and corrosion. It is also the main source of rhenium, a very rare metal. Large mines, such as Climax and Henderson in Colorado or Questa in New Mexico, are “porphyry” deposits, where the ore is dispersed through a large mass of rock.

Powdered molybdenum disulphide is also used as a dry lubricant. In the early 20th century, molybdenite crystals served as detectors in the first radio sets, with a fine metal point (the “cat’s whisker”). It is therefore not a jewellery mineral: it is too soft and too messy.

Traditional symbolism

In the world of crystals, molybdenite is rare and poorly documented. Its metallic lustre and flaky texture evoke concentration, lucidity and sorting out ideas; it is sometimes used as a stone for study or reflection.

These associations are recent and symbolic. No ancient tradition is attached to it, since the mineral was only distinguished in the 18th century. No study shows any effect on attention or health.

Traditional correspondences

Domain	Correspondence cited
Chakra	third eye, sometimes the throat
Element	air or earth, depending on the author
Signs	Virgo, Aquarius (very variable)
Keywords	concentration, lucidity, order

These links are few and differ widely from one author to another. See the third eye chakra and the origin of the chakras.

Safety: a molybdenum sulphide

Never in the mouth, and out of reach of children and animals.
No elixirs: do not let the stone soak in water you drink.
Dust: the mineral flakes and leaves fine metallic dust. Do not breathe it in: do not file, sand or saw it without a mask and ventilation. Fine dust of molybdenum and its compounds irritates the eyes and airways.
Hands: wash your hands after handling, especially before eating or touching your face.
Heat: do not heat or burn it; sulphides give off sulphur dioxide, an irritant.
Environment: do not pour washing water into a stream.

How to use it

As a collector’s piece: a piece of rock with molybdenite flakes, in a closed box or display case.
As a study object: placed next to a piece of graphite, to learn to tell them apart.
Not as jewellery: the stone is far too soft, and it stains clothes and skin.

If you use it for meditation, hold it only briefly and wash your hands afterwards (tutorial).

Care and cleansing

Cleaning: a blower bulb or a very soft brush. Do not rub: the flakes wear off.
Water: unnecessary, and best avoided as a precaution.
Storage: alone, in a closed box, with gloves for handling if possible; it stains other stones and cardboard.
Knocks: the extreme softness of the stone makes it fragile.
Symbolic cleansing: sound, smoke or moonlight (guide).

Recognising molybdenite and telling it apart from graphite

Sign	Molybdenite	Graphite	Galena
Streak on paper	bluish grey	black, greasy	lead grey
Weight	heavy (about 4.7)	light (about 2.2)	very heavy (7.2 to 7.6)
Shape	flexible hexagonal flakes	scales or black masses	grey cubes
Hardness	1 to 1.5	1 to 2	2.5

The best clue remains density, which is higher than that of graphite, and the colour of the streak on a sheet of paper (a harmless test). See galena and the streak of a mineral. Imitations are rare: it is generally sold raw, on its host rock. See real or fake stone? and Our commitments.

How to choose

Choose a piece with visible flakes on a host rock (quartz, granite), well kept in a bag or box. Fine crystal specimens are rare; samples of flaky rock are affordable. Ask about the origin of the piece. It is meant for collecting and study, not for wearing.

Pairings: with rutilated quartz or pyrite, which are sometimes found in the same mineralised areas.