mineral
Tumbled blue-gray stone beads, likely labradorite or dyed quartz
Probable labradorite (plagioclase feldspar; approximately NaAlSi₃O₈–CaAl₂Si₂O₈), though exact identification requires testing
AI-generated identification · may be incorrectHardness about 6–6.5 Mohs for labradorite; blue-gray, translucent to opaque, vitreous luster, granular crystal structure, and two cleavage directions. The rounded, glossy surfaces indicate tumbling and polishing; visible blue flashes would support labradorite, while uniform color may indicate dyeing or another stone.
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Physical properties
Hardness about 6–6.5 Mohs for labradorite; blue-gray, translucent to opaque, vitreous luster, granular crystal structure, and two cleavage directions. The rounded, glossy surfaces indicate tumbling and polishing; visible blue flashes would support labradorite, while uniform color may indicate dyeing or another stone.
Formation & geological history
Labradorite crystallizes in slowly cooled mafic igneous rocks such as basalt, gabbro, and anorthosite, typically in Precambrian to younger intrusive settings. It commonly forms through magmatic crystallization and later weathering releases pieces into sediment.
Uses & applications
Used as ornamental stone, beads, cabochons, carvings, and collector specimens; it has limited construction use. Similar blue-gray tumbled stones are inexpensive jewelry materials.
Geological facts
Labradorescence—bright blue, green, or gold internal flashes caused by light interference across feldspar lamellae—is the key diagnostic feature. A refractive index, hardness, and dye test can distinguish it from dyed quartz or glass.
Field identification & locations
Common sources include Labrador, Canada; Finland; Madagascar; Norway; and Russia. Typical bead value is about $5–$30 for a strand, or $1–$10 per bead; verified high-flash material may cost more.
