How to identify Cat's Eye Quartz

To correctly identify Cat's Eye Quartz (Quartz (variety: Cat'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

   Variable, commonly gray, green, yellow, brown, white. The color is often influenced by the type of fibrous inclusions.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Vitreous (glassy) to greasy, with a silky sheen on the chatoyant band.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Typically massive or granular, often polished into a smooth cabochon to best display the chatoyancy.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Usually found as massive aggregates or in veins. Individual crystals are typically prismatic, but the cat's eye effect is best observed in polished, non-faceted forms.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   None, due to its cryptocrystalline or massive nature.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Hydrothermal veins, pegmatites, and metamorphic rocks where conditions allow for the growth of quartz with oriented fibrous inclusions (e.g., rutile, amphibole).

Key Facts

Hardness

7 on the Mohs scale

Specific Gravity

2.65 g/cm³

Crystal System

Trigonal

Color

Variable, commonly gray, green, yellow, brown, white

Luster

Vitreous to greasy, silky on chatoyant band

Transparency

Translucent to opaque

Fracture

Conchoidal

Cleavage

None

Composition

Silicon dioxide (SiO2) with fibrous inclusions

Physical characteristics

• Crystal Habit: Massive, granular, or prismatic crystals (though chatoyancy is best in massive forms cut as cabochons)
• Cleavage Type: None
• Fracture Type: Conchoidal
• Tenacity: Brittle
• Luster Type: Vitreous to greasy, silky

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