Corrensite is a regular mixed-layer clay mineral composed of alternating chlorite and swelling trioctahedral smectite layers. It typically forms as an alteration product in volcanic or sedimentary rocks and is often identified via X-ray diffraction due to its subtle structural differences from standard chlorite.
Is this corrensite?
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 corrensite with a known reference. Corrensite sits at Mohs 2-3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Corrensite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Corrensite typically shows a earthy luster.
- 4Match the color rangeCompare against the expected color range: green, yellow, white, gray, brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: platy.
Often confused with
Corrensite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside corrensite
Minerals reported to co-occur with corrensite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Mg,Fe)₉(Si,Al)₈O₂₀(OH)₁₀·nH₂O
- Mohs hardness
- 2-3
- Density
- 2.4-2.8 g/cm³
- Streak
- White
- Luster
- Earthy
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Platy
- Cleavage
- Perfect Basal
- Rarity
- Uncommon
- Uses
- Collector, Scientific Research
- Host rock
- Hydrothermal Alteration Zones and Sedimentary Deposits
- Typical price
- $10-50 per specimen
Where rockhounds find corrensite
Classic worldwide localities
- Germany
- USA
- France
- Russia
- Czech Republic
Field-hunting tip
Look in hydrothermal alteration zones and sedimentary deposits country — that is the host setting where corrensite typically forms. If you start seeing calcite, dolomite, quartz in float, you are in the right ground. Field specimens usually show a platy habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find corrensite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
