Chromphyllite is a chromium-rich member of the mica group, characterized by its distinctive and vibrant emerald-green color. Collectors look for scaly or platy aggregates typically found in metamorphic environments associated with chromite deposits.
Is this chromphyllite?
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 chromphyllite with a known reference. Chromphyllite sits at Mohs 3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: whitish green.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: emerald green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: platy, pseudo hexagonal.
Often confused with
Chromphyllite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Chromphyllite leaves whitish green, Fuchsite leaves white; luster reads vitreous on Chromphyllite and pearly on Fuchsite.
How to tell apart: Streak differs, so Chromphyllite leaves whitish green, Muscovite leaves white.
Often found alongside chromphyllite
Minerals reported to co-occur with chromphyllite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- K(Cr,Al)₂(AlSi₃O₁₀)(OH)₂
- Mohs hardness
- 3
- Density
- 2.88 g/cm³
- Colors
- Streak
- Whitish green
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Platy, pseudo hexagonal
- Cleavage
- Perfect on {001}
- Rarity
- Rare
- Uses
- Collector, Scientific research
- Host rock
- Cr-enriched layers in quartz-diopside rocks
Where rockhounds find chromphyllite
Classic worldwide localities
- Slyudyanka complex, Southern Lake Baikal region, Siberia, Russia (type locality)
Field-hunting tip
Where it forms: Cr-enriched layers in quartz-diopside rocks. If you start seeing quartz, chromite, kyanite in float, you are in the right ground. Typical habit: platy, pseudo hexagonal. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify chromphyllite?+
Where is chromphyllite found?+
What rocks look like chromphyllite?+
What minerals are found with chromphyllite?+
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Find chromphyllite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
