Talc is the softest known mineral and serves as the standard for 1 on the Mohs scale. It typically occurs as foliated or massive aggregates with a distinct greasy or soapy feel, often found in magnesium-rich metamorphic rocks.
Is this talc?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch talc with a known reference. Talc sits at Mohs 1, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: pearly, greasy, dull.
- 4Match the color rangeCompare against the expected color range: white, gray, green, silver, pale yellow, pale green, gray white, yellowish white, brownish white.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: foliated, massive, scaly.
Often confused with
Talc vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside talc
Minerals reported to co-occur with talc. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mg₃Si₄O₁₀(OH)₂
- Mohs hardness
- 1
- Density
- 2.58-2.83 g/cm³
- Streak
- White
- Luster
- Pearly, greasy, dull
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Foliated, massive, scaly
- Cleavage
- Perfect on {001}
- Fluorescence
- Orange yellow under SW UV; yellow under LW UV
- Rarity
- Common
- Uses
- Industrial, Lapidary, Decorative
- Host rock
- In talc-rich schists or steatite through hydrothermal alteration of mafic rocks (steatitization) subsequent to serpentinization during greenschist facies metamorphism
Where rockhounds find talc
14 mapped spotsClassic worldwide localities
- Fowler, St. Lawrence Co., New York, USA
- Delta, York Co., Pennsylvania, USA
- Smithfield, Providence Co., Rhode Island, USA
- Rochester, Windsor Co., Vermont, USA
- Mt. Greiner, Zillertal, Tirol, Austria
- Zermatt, Valais, and St. Gotthard, Ticino, Switzerland
Field-hunting tip
Where it forms: In talc-rich schists or steatite through hydrothermal alteration of mafic rocks (steatitization) subsequent to serpentinization during greenschist facies metamorphism. If you start seeing actinolite, tremolite, chlorite in float, you are in the right ground. Typical habit: foliated, massive, scaly. Train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in North Carolina, Massachusetts, New York. Start trip planning there.
More talc photos
Common questions
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Find talc on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
