How to identify Tiger's Eye
Tiger's Eye (a variety of Chalcedony, 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, 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 to reddish-brown, often with dark brown or black bands. Hawk's Eye (blue Tiger's Eye) is blue-gray to blue-green.
- 2
Luster
How the surface reflects light: metallic, vitreous, dull
Silky to vitreous when polished, exhibiting strong chatoyancy.
- 3
Texture
Grain size and surface feel: coarse, fine, glassy
Fibrous, often visible on unpolished surfaces or under magnification. Smooth and polished on finished pieces.
- 4
Crystal Form
Shape of visible crystals or crystal faces
Cryptocrystalline, forming fibrous aggregates. Does not exhibit macroscopic crystal forms.
- 5
Cleavage
How it breaks: flat cleavage planes vs irregular fracture
None, due to its cryptocrystalline nature.
- 6
Geological Environment
The rock formation and setting where it occurs
Typically found in highly metamorphosed iron formations, often associated with asbestos deposits (crocidolite). Occurs in veins or seams within host rocks that have undergone silicification.
Key Facts
- Hardness
- 6.5-7 on the Mohs scale
- Specific Gravity
- 2.64-2.71
- Crystal System
- Trigonal (as quartz/chalcedony)
- Color
- Golden-yellow, golden-brown, reddish-brown, sometimes blue-gray (Hawk's Eye)
- Luster
- Silky to vitreous, chatoyant
- Transparency
- Opaque to translucent
- Fracture
- Conchoidal to splintery
- Cleavage
- None
- Composition
- Silicon dioxide (SiO2) with inclusions of iron oxides (goethite) and relict amphibole fibers.
Physical characteristics
- Crystal Habit: Cryptocrystalline, fibrous aggregates, pseudomorph after crocidolite.
- Cleavage Type: None
- Fracture Type: Conchoidal to splintery
- Tenacity: Brittle
- Luster Type: Silky to vitreous
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