How to identify Tiger's Eye

To correctly identify Tiger's Eye (Tiger's Eye (a variety of Chalcedony, which is cryptocrystalline Quartz)), 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

   Golden-brown, yellow-brown, reddish-brown, sometimes blue (Hawk's Eye). The colors are typically banded or streaked.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Silky to vitreous, especially on polished surfaces, due to chatoyancy.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Fibrous internal structure, often visible as parallel lines or bands. Smooth to the touch when polished.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Massive, fibrous aggregates. Does not form macroscopic crystals.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   None, as it is cryptocrystalline quartz.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Typically found in metamorphosed ultramafic rocks, often associated with serpentinite bodies, where crocidolite asbestos veins have been replaced by quartz. It forms in veins or seams within these host rocks.

Key Facts

Hardness

6.5-7 on the Mohs scale

Specific Gravity

2.64 - 2.71

Crystal System

Trigonal (cryptocrystalline)

Color

Golden-brown, yellow-brown, reddish-brown, blue (Hawk's Eye)

Luster

Silky to vitreous

Transparency

Opaque to translucent

Fracture

Conchoidal to splintery

Cleavage

None

Composition

Silicon dioxide (SiO2) with inclusions of limonite and relict crocidolite fibers

Physical characteristics

• Crystal Habit: Massive, fibrous aggregates, pseudomorph after crocidolite
• Cleavage Type: None
• Fracture Type: Conchoidal to splintery
• Tenacity: Brittle
• Luster Type: Silky (chatoyant) to vitreous

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