Hawk's Eye Identification Guide

What Hawk's Eye Looks Like

Hawk's eye (falcon's eye) is a chatoyant blue-grey to blue-green quartz, the unoxidized relative of tiger's eye. It forms when quartz replaces fibrous crocidolite (blue asbestos) while preserving the parallel fiber structure, producing a silky, moving band of light (chatoyancy) across the polished surface. Colors are slate-blue, grey-blue, and greenish-grey, with a soft satiny sheen and silky luster.

• Color: blue-grey, slate-blue, greenish-grey
• Transparency: translucent to opaque
• Luster: silky to vitreous on polished surfaces
• Habit: massive fibrous quartz; cut as cabochons to show the eye/band

Step-by-Step Field-ID Checklist

1. Roll under light. A single bright band of reflected light should glide across the dome — the chatoyant "eye."
2. Note the color. Blue-grey to greenish tone distinguishes hawk's eye from the golden-brown of tiger's eye.
3. Check the fiber direction. The silky bands run parallel; the sheen is perpendicular to the fibers.
4. Test hardness. It scratches glass easily (quartz, H=7).
5. Look for transitional zones. Specimens often grade from blue (hawk's eye) into golden brown (tiger's eye) where oxidation occurred.

Key Diagnostic Tests

• Mohs hardness: 7 — scratches glass and steel; not scratched by a knife.
• Streak: white.
• Fracture: conchoidal to splintery; no cleavage.
• Specific gravity: ~2.6–2.7 — typical of quartz.
• Optical effect: chatoyancy from parallel fibrous inclusions (pseudomorph after crocidolite).
• Acid: no reaction.

Common Look-Alikes and How to Tell Them Apart

• Tiger's eye: same material but golden-brown to reddish from oxidized iron; hawk's eye keeps the original blue-grey of the crocidolite.
• Pietersite: a brecciated, swirled tiger's/hawk's eye with chaotic, multidirectional chatoyancy; hawk's eye has a single straight band.
• Blue chalcedony / blue quartz: lacks the silky moving band (no chatoyancy).
• Labradorite: shows broad color flash (labradorescence) and has cleavage; hawk's eye is quartz (no cleavage) with a single chatoyant band.
• Dyed/imitation cat's-eye glass: shows a too-sharp, glassy eye and gas bubbles; natural hawk's eye has a softer, fibrous sheen and is harder than glass.

The core combination is quartz hardness (7) + silky single-band chatoyancy + blue-grey color.

Where Hawk's Eye Is Found

The principal source is the Northern Cape, South Africa (Griqualand West / Asbestos Mountains), where it occurs with tiger's eye in banded ironstone. Additional material comes from Western Australia, India, Namibia, and Brazil.

Quick Field Summary

A blue-grey, silky quartz that scratches glass and shows a single bright chatoyant band gliding across a polished dome is hawk's eye — the unoxidized blue counterpart of golden tiger's eye, distinct from chalcedony, labradorite, and glass imitations.