Clintonite is a brittle mica found primarily in contact-metamorphosed limestones and skarns. It typically forms tabular, six-sided crystals that appear more rigid and less flexible than other common micas.
Is this clintonite?
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 clintonite with a known reference. Clintonite sits at Mohs 3.5-6, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white, slightly yellow-gray.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous, pearly, submetallic.
- 4Match the color rangeCompare against the expected color range: colorless, green, yellow, red, reddish brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: massive, radial.
Often confused with
Clintonite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads vitreous, pearly, submetallic on Clintonite and splendent to submetallic, vitreous, pearly on cleavage on Biotite.
How to tell apart: Luster reads vitreous, pearly, submetallic on Clintonite and pearly to submetallic on cleavage on Phlogopite.
Often found alongside clintonite
Minerals reported to co-occur with clintonite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca(Mg,Al)₃(Al₃Si)O₁₀(OH)₂
- Mohs hardness
- 3.5-6
- Density
- 3.0-3.1 g/cm³
- Streak
- White, slightly yellow-gray
- Luster
- Vitreous, pearly, submetallic
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Massive, radial
- Cleavage
- {001}, perfect
- Rarity
- Uncommon
- Uses
- Collector
- Host rock
- In chlorite schists; in metasomatically altered limestones; in siliceous skarns near contact metamorphic zones
Where rockhounds find clintonite
Classic worldwide localities
- Amity, Edenville, and Warwick, Orange Co., New York, USA
- Crestmore, Riverside Co., California, USA
- Ludwig, Lyon Co., Nevada, USA
- Sulzer, Prince of Wales Island, Alaska, USA
- Mt. Monzoni and at Mts. Castone and Adamello, Trentino-Alto Adige, Italy
- Pargas district, Finland
Field-hunting tip
Where it forms: In chlorite schists; in metasomatically altered limestones; in siliceous skarns near contact metamorphic zones. If you start seeing talc, spinel, grossular in float, you are in the right ground. Typical habit: massive, radial. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify clintonite?+
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Find clintonite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
