How to identify Blue Tiger's Eye

To correctly identify Blue Tiger's Eye (Hawk's Eye (variety of Tiger's Eye, a form of 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

   Blue-gray to blue-green, often with darker bands. The color is uniform within the fibrous bands.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Silky to vitreous, especially on polished surfaces, exhibiting strong 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

   Typically massive, occurring as veins or lenses. Individual quartz crystals are microscopic (cryptocrystalline).

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   None, as it is a cryptocrystalline quartz.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Found in metamorphosed iron formations, particularly those rich in crocidolite. It forms in areas where silica-rich fluids have permeated and replaced the original crocidolite asbestos.

Key Facts

Hardness

6.5-7 on the Mohs scale

Specific Gravity

2.64-2.71

Crystal System

Trigonal (cryptocrystalline)

Color

Blue-gray, blue-green, sometimes with golden-brown streaks

Luster

Silky to vitreous, chatoyant

Transparency

Opaque to translucent

Fracture

Conchoidal to splintery

Cleavage

None

Composition

Silicon dioxide (SiO2) with embedded crocidolite fibers

Physical characteristics

• Crystal Habit: Massive, fibrous aggregates, pseudomorphs after crocidolite
• Cleavage Type: None
• Fracture Type: Conchoidal to splintery, due to the cryptocrystalline nature and fibrous inclusions
• Tenacity: Brittle
• Luster Type: Silky (due to fibrous inclusions) to vitreous (of the quartz matrix)

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