How to identify Tiger's Eye
Tiger's Eye (a variety of Chalcedony, a cryptocrystalline form of silica)
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Open the appTo correctly identify Tiger's Eye (Tiger's Eye (a variety of Chalcedony, a cryptocrystalline form of silica)), 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 golden-brown, reddish-brown, with characteristic shimmering bands.
- 2
Luster
How the surface reflects light: metallic, vitreous, dull
Silky to vitreous when polished, due to the fibrous structure.
- 3
Texture
Grain size and surface feel: coarse, fine, glassy
Fine-grained, fibrous, cryptocrystalline. When broken, it can show a splintery or conchoidal fracture.
- 4
Crystal Form
Shape of visible crystals or crystal faces
Massive, fibrous aggregates, typically forming veins or layers within host rock. Does not form macroscopic crystals.
- 5
Cleavage
How it breaks: flat cleavage planes vs irregular fracture
None, as it is a cryptocrystalline aggregate of quartz.
- 6
Geological Environment
The rock formation and setting where it occurs
Found in metamorphosed iron formations, particularly those containing crocidolite asbestos. It forms through metasomatic replacement processes in low-grade metamorphic conditions.
Key Facts
- Hardness
- 6.5-7 on the Mohs scale (due to quartz).
- Specific Gravity
- 2.64-2.71 g/cm³.
- Crystal System
- Trigonal (as quartz, but cryptocrystalline).
- 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 inclusions of iron oxides (limonite).
Physical characteristics
- Crystal Habit: Massive, fibrous aggregates, pseudomorph after crocidolite.
- Cleavage Type: None.
- Fracture Type: Conchoidal to splintery.
- Tenacity: Brittle.
- Luster Type: Silky (due to fibrous structure) to vitreous (when polished).
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