Chlorite Schist Identification Guide
Identify chlorite schist by its green color, soft flaky foliation, silky sheen, and greasy feel versus greenstone and other schists.
Read the full Chlorite Schist encyclopedia entry →
What Chlorite Schist Looks Like
Chlorite schist is a foliated metamorphic rock dominated by the soft green mineral chlorite. It is characteristically green to greyish-green or dark green, with a silky to pearly sheen on its foliation surfaces and a scaly, flaky, layered (schistose) texture. The rock splits readily along its foliation into wavy sheets that feel smooth or slightly greasy. Shiny chlorite flakes catch the light, and the rock is comparatively soft and easily scratched.
Step-by-Step Field ID Checklist
- Color: Confirm a distinctly green to grey-green foliated rock.
- Foliation: Look for parallel flaky layers that split into wavy sheets.
- Sheen and feel: Note a silky sheen and smooth, slightly greasy or soapy touch.
- Hardness test: Chlorite is soft (Mohs ~2–2.5); a fingernail or knife scratches the flakes.
- Flexibility: Thin chlorite flakes bend but are not elastic (unlike mica).
- Acid test: No fizz (silicate rock).
Key Diagnostic Tests
- Hardness: Chlorite ~2–2.5; the rock is easily scratched, though it may contain harder grains.
- Foliation/cleavage: Pronounced schistosity; splits into flexible non-elastic flakes.
- Luster: Silky to pearly green.
- Density: ~2.6–3.0 g/cm³.
- Acid reaction: None.
Common Look-Alikes and How to Tell Them Apart
- Greenstone / greenschist: Greenschist is closely related but contains more actinolite, epidote, and albite; chlorite schist is dominated by soft green chlorite and is softer overall.
- Mica schist: Has shinier, elastic mica flakes (silver or brown) that snap back; chlorite flakes are green and bend without springing back.
- Talc schist / soapstone: Even softer (Mohs 1) and greasier; chlorite schist is slightly harder and greener.
- Serpentinite: More massive and waxy, often mottled; chlorite schist is clearly foliated and flaky.
- Phyllite: Finer-grained with a silky sheen but smoother surface; chlorite schist shows larger visible flakes.
Where Chlorite Schist Is Typically Found
Chlorite schist forms under low-grade (greenschist-facies) regional metamorphism of mafic igneous rocks (basalt, tuff) or iron-magnesium-rich sediments. It is common in mountain belts and ancient shield terranes, including the Alps, Appalachians, Scottish Highlands, and Precambrian greenstone belts. Look for green, flaky outcrops in metamorphic terrain, often near former volcanic rocks.
Frequently asked questions
How do you identify chlorite schist?
Chlorite schist is a green, foliated metamorphic rock with soft, flaky layers that split into wavy sheets, a silky sheen, a greasy feel, and a low hardness (the chlorite scratches with a knife).
What is the difference between chlorite schist and mica schist?
Mica schist has shiny, elastic silver or brown mica flakes that spring back when bent, while chlorite schist is green with softer flakes that bend without snapping back.
Why is chlorite schist green?
Its color comes from the mineral chlorite, an iron- and magnesium-bearing sheet silicate that forms during low-grade metamorphism of mafic rocks.
Is chlorite schist soft?
Yes, the chlorite that dominates the rock has a hardness of only about 2–2.5, so chlorite schist is relatively soft and easily scratched, though it may contain harder mineral grains.
Chlorite Schist identified by the community
Recent Chlorite Schist specimens identified with Rock Identifier.
