Clinojimthompsonite is a rare chain silicate mineral that forms as a structural variation of jimthompsonite. It is typically found in association with other magnesium silicates in altered ultramafic rocks and is often difficult to distinguish from its orthorhombic counterpart without X-ray diffraction analysis.
Is this clinojimthompsonite?
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 clinojimthompsonite with a known reference. Clinojimthompsonite 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. Clinojimthompsonite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Clinojimthompsonite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: green, brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals.
Often confused with
Clinojimthompsonite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Jimthompsonite is the harder of the two (Mohs 5-6 vs. 2-3).
How to tell apart: Anthophyllite is the harder of the two (Mohs 5.5-6 vs. 2-3).
How to tell apart: Clinojimthompsonite is noticeably harder (Mohs 2-3 vs. 1); luster reads vitreous on Clinojimthompsonite and pearly on Talc.
Often found alongside clinojimthompsonite
Minerals reported to co-occur with clinojimthompsonite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Mg,Fe)₅Si₆O₁₆(OH)₂
- Mohs hardness
- 2-3
- Density
- 3.3 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic Crystals
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Metamorphic Ultramafic Rocks
- Typical price
- $50-300 per specimen
Where rockhounds find clinojimthompsonite
Classic worldwide localities
- Vermont, USA
- Pennsylvania, USA
Field-hunting tip
Look in metamorphic ultramafic rocks country — that is the host setting where clinojimthompsonite typically forms. If you start seeing jimthompsonite, anthophyllite, talc in float, you are in the right ground. Field specimens usually show a prismatic crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find clinojimthompsonite on the map
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