How to identify Red Tiger's Eye

To correctly identify Red Tiger's Eye (Quartz (variety of 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

   Deep reddish-brown to brick-red, often with streaks of darker or lighter red. The color is uniform throughout the chatoyant bands.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Silky to vitreous, especially on polished surfaces, with a distinct chatoyancy.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Fine-grained, fibrous appearance internally, though externally smooth when polished. Can feel cool and dense.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Massive, cryptocrystalline aggregates, typically forming veins or layers. Does not exhibit macroscopic crystal faces.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   None, due to its cryptocrystalline nature.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Found in metamorphosed banded iron formations or other environments where crocidolite asbestos has been altered by silica-rich hydrothermal fluids or metasomatism. Often associated with serpentinites and other metamorphic rocks.

Key Facts

Hardness

6.5-7 on the Mohs scale (due to quartz composition).

Specific Gravity

2.64-2.71 g/cm³.

Crystal System

Trigonal (as quartz).

Color

Reddish-brown, brick-red, often with golden or darker streaks.

Luster

Silky to vitreous, chatoyant.

Transparency

Opaque to translucent.

Fracture

Conchoidal to splintery.

Cleavage

None.

Composition

Silicon dioxide (SiO₂) with fibrous inclusions of iron oxides (hematite, goethite) that replaced crocidolite.

Physical characteristics

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

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