Paragonite Schist Identification Guide
A field guide to recognizing paragonite schist, a sodium-mica schist easily confused with ordinary muscovite mica schist.
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What Paragonite Schist Looks Like
Paragonite schist is a foliated metamorphic rock dominated by paragonite, the sodium-rich white mica (NaAl2(AlSi3O10)(OH)2), the sodium analogue of muscovite. It looks much like a pale, silvery mica schist: a fine- to medium-grained, strongly foliated rock with a silky to pearly sheen on cleavage surfaces, splitting readily into wavy sheets. Color is whitish, silvery, pale green, or gray. It commonly carries quartz, and may host garnet, kyanite, or chloritoid.
- Color: silvery white, pale gray to greenish
- Texture: schistose (well-foliated), shiny mica-rich layers
- Luster: pearly to silky on mica sheets
- Habit: foliated rock that splits into flaky/wavy layers
Step-by-Step Field ID Checklist
- Confirm schistosity - strong planar foliation that splits into sheets.
- Identify the mica sheen - silvery, fine flakes coating foliation planes.
- Hardness. Mica is soft (2-3); flakes peel and bend elastically.
- Look for index minerals (garnet, kyanite, chloritoid) suggesting medium-grade metamorphism.
- Note the pale color. Paragonite tends slightly more chalky-white than golden muscovite.
- Caution: paragonite and muscovite are nearly indistinguishable by eye - lab/chemical tests confirm sodium content.
Key Diagnostic Tests
- Mohs hardness: ~2-3 (mica) overall; quartz grains harder.
- Streak: white.
- Cleavage: perfect basal (one direction), peels into thin elastic sheets.
- Density: ~2.8 g/cm3 for the mica.
- Definitive ID: XRD or microprobe needed to confirm paragonite versus muscovite (Na vs K).
Common Look-Alikes and How to Tell Them Apart
- Muscovite (mica) schist: visually almost identical; paragonite is the Na-mica and requires chemical/XRD confirmation - muscovite is more common and often slightly more golden.
- Sericite/phyllite: finer-grained with a more satiny sheen and less obvious individual flakes; phyllite is lower grade.
- Talc schist: much softer (Mohs 1), greasy feel, will not show crisp mica flakes.
- Chlorite schist: greener, with non-elastic flakes and lower luster.
Where It Is Found
Paragonite schist forms during regional metamorphism of aluminous, sodium-bearing sedimentary protoliths (pelites) at medium grades. It occurs in metamorphic belts such as the Alps, the Appalachians, and other orogenic terrains, often interlayered with muscovite schist and quartzite.
Frequently asked questions
What is paragonite schist?
It is a foliated metamorphic rock dominated by paragonite, the sodium-rich white mica, resembling a pale silvery mica schist and formed by regional metamorphism of aluminous sediments.
How do you tell paragonite schist from muscovite schist?
They look nearly identical; reliable separation requires chemical analysis or X-ray diffraction because paragonite is the sodium mica and muscovite is the potassium mica.
What does paragonite schist look like?
A silvery white to pale greenish, strongly foliated rock with a pearly mica sheen that splits into thin wavy sheets, often with quartz and minor garnet or kyanite.
Where is paragonite schist found?
In medium-grade metamorphic belts such as the Alps and Appalachians, interlayered with muscovite schist and quartzite.
Paragonite Schist identified by the community
Recent Paragonite Schist specimens identified with Rock Identifier.
