Phyllite is a low-to-medium grade metamorphic rock that represents an intermediate stage between slate and schist. It is characterized by a distinct silky sheen on its foliation surfaces caused by the growth of microscopic mica flakes, distinguishing it from the duller appearance of slate.
Is this phyllite?
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 phyllite with a known reference. Phyllite sits at Mohs 1-2, softer than the next harder reference, harder than the previous one.
- 2Read the textureLook at a fresh break with a hand lens. Texture: Foliated, with a silky sheen; foliation often crinkled or wavy. Grain size: Fine-grained; crystals not visible to the naked eye.
- 3Pick out the mineralsComposition: Mainly quartz, sericite mica and chlorite. Identify the two or three most abundant grains.
- 4Read the lusterHold the specimen under a strong light. Luster: silky.
- 5Match the color rangeCompare against the expected color range: silvery-gray, greenish-gray, black.
Often confused with
Phyllite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Schist is the harder of the two (Mohs 3-6 vs. 1-2); luster reads silky on Phyllite and pearly on Schist.
How to tell apart: Luster reads silky on Phyllite and dull on Slate.
How to tell apart: Luster reads silky on Phyllite and pearly on Mica.
Often found alongside phyllite
Minerals reported to co-occur with phyllite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Mohs hardness
- 1-2
- Density
- 2.7-2.9 g/cm³
- Luster
- Silky
- Transparency
- Opaque
- Rarity
- Common
- Uses
- Decorative, Educational
- Host rock
- metamorphic terrains
- Texture
- Foliated, with a silky sheen; foliation often crinkled or wavy
- Grain size
- Fine-grained; crystals not visible to the naked eye
- Composition
- Mainly quartz, sericite mica and chlorite
Where rockhounds find phyllite
1 mapped spotsClassic worldwide localities
- Vermont, USA
- Scotland
- Norway
- Alps, Europe
- New Zealand
Field-hunting tip
Where it forms: metamorphic terrains. If you start seeing quartz, muscovite, chlorite in float, you are in the right ground. In the U.S., the densest reported localities are in Nevada. Start trip planning there.
Common questions
How do you identify phyllite?+
Where is phyllite found?+
Can I find phyllite in the United States?+
What rocks look like phyllite?+
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Find phyllite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
