How to identify Tiger's Eye

To correctly identify Tiger's Eye (Tiger's Eye), 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-yellow to reddish-brown, often with iridescent bands. Hawk's Eye (blue Tiger's Eye) is blue to bluish-green.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Silky to vitreous, exhibiting strong chatoyancy.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Fibrous appearance, even when polished smooth. Can feel cool and smooth to the touch.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Massive, fibrous aggregates, typically found in veins. Does not form distinct macroscopic crystals.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   None, as it is a microcrystalline quartz. The original crocidolite had perfect cleavage, but this is not retained in the quartz pseudomorph.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Formed in metamorphic terrains where crocidolite-rich rocks (often associated with banded iron formations) have undergone silicification. Typically found in veins or seams within these host rocks.

Key Facts

Hardness

7 (Mohs scale)

Specific Gravity

2.64 - 2.71

Crystal System

Trigonal (as quartz)

Color

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

Luster

Silky, vitreous

Transparency

Opaque to translucent

Fracture

Conchoidal to splintery

Cleavage

None

Composition

Silicon dioxide (SiO2) with inclusions of iron oxides (limonite, goethite) and relict crocidolite fibers.

Physical characteristics

• Crystal Habit: Massive, fibrous aggregates, pseudomorph after crocidolite.
• Cleavage Type: None (as quartz). Original crocidolite had perfect cleavage.
• Fracture Type: Conchoidal to splintery.
• Tenacity: Brittle.
• Luster Type: Silky to vitreous, chatoyant.

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