How to identify Serpentine

To correctly identify Serpentine (Serpentine group minerals), check each of these features in order. Many rocks and minerals look alike, so cross-reference multiple properties before deciding.

Step-by-step identification

1. 1

   Color

   Overall color and any zoning or banding

   Typically shades of green (light to dark, yellowish-green, olive-green, bluish-green), sometimes brownish, blackish, or mottled.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Greasy, waxy, silky (especially chrysotile), or dull.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Smooth, soapy, or fibrous. Often feels slippery to the touch.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Massive, platy (antigorite), fine-grained (lizardite), or fibrous (chrysotile). Individual crystals are rarely macroscopic.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Perfect basal cleavage in antigorite and lizardite, but often not observed in massive forms. Chrysotile exhibits fibrous parting.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Associated with ophiolite complexes, subduction zones, and areas where oceanic crust or mantle rocks have been uplifted and hydrated. Found in metamorphic terrains derived from ultramafic protoliths.

Key Facts

Hardness

2.5-5.0 on Mohs scale (varies by mineral: chrysotile ~2.5-3, lizardite ~2.5-4, antigorite ~3.5-5)

Specific Gravity

2.5-2.9 g/cm (varies slightly by mineral)

Crystal System

Monoclinic (chrysotile, lizardite), Orthorhombic (antigorite)

Color

Green, yellowish-green, brownish-green, blackish-green, often mottled

Luster

Greasy, waxy, silky (fibrous varieties), dull

Transparency

Translucent to opaque

Fracture

Conchoidal to splintery (antigorite), fibrous (chrysotile)

Cleavage

Perfect basal cleavage (001) in antigorite and lizardite, but often not visible in massive forms. Chrysotile exhibits fibrous parting.

Composition

Hydrous magnesium iron phyllosilicate

Physical characteristics

• Crystal Habit: Massive, platy, lamellar, fibrous, fine-grained, pseudomorphic after olivine or pyroxene.
• Cleavage Type: Perfect basal (001) in antigorite and lizardite, but often indistinct in massive aggregates. Chrysotile has fibrous parting.
• Fracture Type: Conchoidal to splintery (antigorite), fibrous (chrysotile).
• Tenacity: Brittle to tough (antigorite), flexible (chrysotile fibers).
• Luster Type: Greasy, waxy, silky, dull.

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