How to identify Tiger's Eye
Tiger's Eye (a variety of Chalcedony, which is a cryptocrystalline form of silica, SiO2)
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Open the appTo correctly identify Tiger's Eye (Tiger's Eye (a variety of Chalcedony, which is a cryptocrystalline form of silica, SiO2)), 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
Color
Overall color and any zoning or banding
Golden-yellow, golden-brown, reddish-brown, sometimes with blue (Hawk's Eye) or red (heated) variations. The colors are typically banded.
- 2
Luster
How the surface reflects light: metallic, vitreous, dull
Silky to vitreous, exhibiting strong chatoyancy (a mobile, shimmering band of light).
- 3
Texture
Grain size and surface feel: coarse, fine, glassy
Fine-grained, fibrous appearance due to the pseudomorphic replacement of crocidolite. When polished, it feels smooth.
- 4
Crystal Form
Shape of visible crystals or crystal faces
Typically massive, occurring in veins or layers. Individual crystals are cryptocrystalline (microscopic).
- 5
Cleavage
How it breaks: flat cleavage planes vs irregular fracture
None, as it is a cryptocrystalline quartz.
- 6
Geological Environment
The rock formation and setting where it occurs
Found in low-grade metamorphic terrains, often associated with serpentinite or other ultramafic rocks where crocidolite-rich veins have undergone silicification.
Key Facts
- Hardness
- 6.5-7 on the Mohs scale
- Specific Gravity
- 2.64-2.71
- Crystal System
- Trigonal (cryptocrystalline)
- Color
- Golden-yellow, golden-brown, reddish-brown
- Luster
- Silky to vitreous, chatoyant
- Transparency
- Opaque to translucent
- Fracture
- Conchoidal to splintery
- Cleavage
- None
- Composition
- Silicon dioxide (SiO2) with fibrous inclusions of altered crocidolite and iron oxides (goethite).
Physical characteristics
- Crystal Habit: Massive, fibrous aggregates, pseudomorph after crocidolite.
- Cleavage Type: Absent
- Fracture Type: Conchoidal to splintery, due to its cryptocrystalline nature and fibrous structure.
- Tenacity: Brittle
- Luster Type: Silky (due to chatoyancy) to vitreous
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