How to identify Serpentine

To correctly identify Serpentine (Serpentine Group), 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, olive, yellowish-green, bluish-green), but can also be yellowish, brownish, or black. Often mottled or veined.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Greasy, waxy, silky (especially fibrous varieties like chrysotile), or dull.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Massive, platy, fibrous, or granular. Often feels smooth or slightly soapy to the touch.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Usually massive, fine-grained, or platy aggregates. Fibrous forms (chrysotile) are common. Individual crystals are rare and microscopic.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Poor to distinct in one direction (basal), but often not observed in massive varieties. Fibrous varieties show cleavage parallel to the fibers.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Ultramafic igneous rocks (peridotite, dunite) that have undergone hydrothermal alteration (serpentinization) in oceanic crust, ophiolites, subduction zones, and metamorphic terrains.

Key Facts

Hardness

2.5 - 4 (Mohs scale)

Specific Gravity

2.5 - 2.9 g/cm

Crystal System

Monoclinic or Orthorhombic (depending on the specific mineral within the group)

Color

Green (various shades), yellowish, brownish, black; often mottled

Luster

Greasy, waxy, silky, dull

Transparency

Translucent to opaque

Fracture

Conchoidal, splintery, or uneven

Cleavage

Poor to distinct basal cleavage (001), often not observed in massive forms. Fibrous varieties show cleavage parallel to fibers.

Composition

Hydrous magnesium iron phyllosilicate

Physical characteristics

• Crystal Habit: Massive, platy, fibrous (asbestiform), lamellar, granular
• Cleavage Type: Basal (001) - poor to distinct
• Fracture Type: Conchoidal, splintery, or uneven
• Tenacity: Brittle to tough (fibrous varieties)
• Luster Type: Greasy, waxy, silky, dull

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