Rock Identifier
Molybdenite in Quartz (Molybdenite (MoS2) with Quartz (SiO2)) — mineral
mineral

Molybdenite in Quartz

Molybdenite (MoS2) with Quartz (SiO2)

Color: Lead-gray to bluish-gray; Luster: Metallic; Hardness: 1-1.5 (very soft, marks paper); Crystal Structure: Hexagonal; Cleavage: Perfect basal; Streak: Greenish-gray.

Hardness
1-1
Color
Lead-gray to bluish-gray
Luster
Metallic
Identified More mineral

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Physical properties

Color: Lead-gray to bluish-gray; Luster: Metallic; Hardness: 1-1.5 (very soft, marks paper); Crystal Structure: Hexagonal; Cleavage: Perfect basal; Streak: Greenish-gray.

Formation & geological history

Formed in high-temperature hydrothermal vein deposits, pegmatites, and contact metamorphic deposits. It is often found associated with quartz, fluorite, and wolframite.

Uses & applications

Molybdenite is the primary ore of molybdenum, which is used to make high-strength steel alloys, lubricants, and catalysts in the petroleum industry.

Geological facts

Molybdenite is so soft and greasy that it was historically confused with graphite. It is a semiconductor and its disulfide structure allows it to function as a dry lubricant similar to graphite.

Field identification & locations

Identify by its metallic lead-gray color, extreme softness (can be scratched by a fingernail), and the greasy feel. It often leaves a bluish or greenish streak on porcelain. Look for it in granitic areas.