gemstone

Hawk's Eye (Falcon's Eye / Blue-Green Tiger's Eye)

Silicified Crocidolite (Quartz pseudomorph after riebeckite, SiO2)

AI-generated identification · may be incorrect

Mohs hardness of 6.5–7; color ranges from deep blue-gray and dark olive-green to golden-green; vitreous to silky luster; trigonal crystal system (cryptocrystalline aggregate); specific gravity of ~2.64–2.71; exhibits prominent chatoyancy (cat's eye effect) caused by parallel fibrous mineral inclusions.

Identified October 3, 2026More gemstone →

Explore Hawk's Eye (Falcon's Eye / Blue-Green Tiger's Eye) in the encyclopedia →

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Physical properties

Formation & geological history

Formed by pseudomorphism during low-grade regional or hydrothermal metamorphism, where quartz gradually replaces fibrous crocidolite (an amphibole mineral) while preserving the parallel fibrous texture.

Uses & applications

Commonly carved and polished into cabochons, spheres, decorative eggs, beads, and ornamental items for jewelry and metaphysical collections.

Geological facts

Hawk's eye is essentially an un-oxidized or partially altered precursor to golden-brown tiger's eye. When polished into a rounded cabochon or egg, the parallel oriented fibers reflect a movable streak of light reminiscent of a feline eye, a phenomenon known as chatoyancy.

Field identification & locations

Recognized by its dark bluish-gray to deep greenish color and distinct silk-like chatoyant band shifting across the surface under a direct light source. Major commercial sources include South Africa (Northern Cape), Western Australia, and Brazil.