How to identify Chrysotile

To correctly identify Chrysotile (Chrysotile (a serpentine mineral)), 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 white, gray, greenish-white, or yellowish-white. Can be stained by iron oxides to reddish-brown.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Silky to greasy when fibrous; dull to waxy when massive.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Characteristically fibrous, often appearing as bundles of fine, flexible, thread-like fibers. Can also be massive.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Typically occurs as cross-fiber veins (fibers perpendicular to vein walls) or slip-fiber veins (fibers parallel to vein walls). Individual crystals are microscopic, forming hollow tubes.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Perfect along the fiber length (due to its fibrous nature), but not a true crystallographic cleavage in the traditional sense for non-fibrous minerals.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Found in serpentinized ultramafic rocks (e.g., serpentinite), often associated with ophiolite complexes, metamorphic terrains, and altered peridotites. It forms in veins within these rocks.

Key Facts

Hardness

2.5-3.0 on Mohs scale (fibers are flexible, not hard)

Specific Gravity

2.50-2.60

Crystal System

Monoclinic

Color

White, gray, greenish-white, yellowish-white

Luster

Silky (fibrous), greasy to waxy (massive)

Transparency

Translucent to opaque

Fracture

Splintery (due to fibrous nature)

Cleavage

Perfect along fiber length (pseudo-cleavage)

Composition

Hydrous magnesium silicate

Physical characteristics

• Crystal Habit: Fibrous, typically in veins (cross-fiber or slip-fiber), also massive.
• Cleavage Type: Pseudo-cleavage, perfect along the length of the fibers.
• Fracture Type: Splintery, due to its fibrous nature.
• Tenacity: Flexible, elastic (fibers).
• Luster Type: Silky to greasy.

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