Hectorite is a rare lithium-bearing clay mineral belonging to the smectite group. It is typically found in soft, earthy masses associated with altered volcanic deposits and is highly valued in industry for its unique rheological properties.
Is this hectorite?
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 hectorite with a known reference. Hectorite sits at Mohs 1-2, 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: earthy to waxy, dull.
- 4Match the color rangeCompare against the expected color range: white.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: aggregates.
Often confused with
Hectorite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside hectorite
Minerals reported to co-occur with hectorite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na₀.₃(Mg,Li)₃Si₄O₁₀(F,OH)₂
- Mohs hardness
- 1-2
- Density
- 2.5 g/cm³
- Colors
- Streak
- White
- Luster
- Earthy to waxy, dull
- Transparency
- Translucent, transparent in thin section
- Crystal system
- Monoclinic
- Crystal habit
- Aggregates
- Cleavage
- {001}, perfect
- Fluorescence
- Weak sky blue under SW UV; bright sky blue under LW UV
- Rarity
- Uncommon
- Uses
- Industrial, Cosmetic, Collector
- Host rock
- In a bentonite deposit, altered from clinoptilolite derived from volcanic tu® and ash with a high glass content, related to hot spring activity (Hector, California, USA)
Where rockhounds find hectorite
Classic worldwide localities
- Five km south of Hector, San Bernardino Co., California, USA
- Lyles deposit, 38 km northeast of Hillside, Yavapai Co., Arizona, USA
- Disaster Peak, in the Montana Mountains, near McDermitt, Disaster district, Humboldt Co., Nevada, USA
- Puy Chalard, Puy-de-Dôme, France
- Balıkesir colemanite deposit, Balıkesir Province, Turkey
Field-hunting tip
Where it forms: In a bentonite deposit, altered from clinoptilolite derived from volcanic tu® and ash with a high glass content, related to hot spring activity (Hector, California, USA). If you start seeing calcite, clinoptilolite in float, you are in the right ground. Typical habit: aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify hectorite?+
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What rocks look like hectorite?+
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Find hectorite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
