How to identify Tiger's Eye
Tiger's Eye (a variety of Chalcedony, which is microcrystalline Quartz)
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Open the appTo correctly identify Tiger's Eye (Tiger's Eye (a variety of Chalcedony, which is microcrystalline 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
Color
Overall color and any zoning or banding
Golden-yellow, golden-brown, reddish-brown, sometimes with darker brown or black bands. The color is due to iron oxide staining.
- 2
Luster
How the surface reflects light: metallic, vitreous, dull
Silky to vitreous, especially noticeable on polished surfaces due to chatoyancy.
- 3
Texture
Grain size and surface feel: coarse, fine, glassy
Fine-grained, fibrous appearance internally, often smooth and polished externally for commercial use.
- 4
Crystal Form
Shape of visible crystals or crystal faces
Cryptocrystalline (microcrystalline) aggregates, typically massive or in veins. Does not form macroscopic crystals.
- 5
Cleavage
How it breaks: flat cleavage planes vs irregular fracture
None, due to its microcrystalline nature.
- 6
Geological Environment
The rock formation and setting where it occurs
Found in metamorphic rocks, particularly those rich in iron and silica, where crocidolite asbestos has been altered. Often occurs in veins or seams within serpentinites or other mafic/ultramafic metamorphic rocks.
Key Facts
- Hardness
- 6.5-7 on the Mohs scale
- Specific Gravity
- 2.64-2.71 g/cm³
- Crystal System
- Trigonal (as quartz)
- Color
- Golden-yellow, golden-brown, reddish-brown
- Luster
- Silky to vitreous
- Transparency
- Opaque to translucent
- Fracture
- Conchoidal to splintery
- Cleavage
- None
- Composition
- Silicon dioxide (SiO2) with fibrous inclusions of goethite (FeO(OH))
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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