mineral
Polished labradorite cabochon
Labradorite, plagioclase feldspar; approximately (Ca,Na)(Al,Si)₄O₈
AI-generated identification · may be incorrectHardness 6–6.5 Mohs; gray to dark gray body with blue-green iridescent labradorescence, vitreous luster, triclinic crystal structure, and two good cleavage directions. The rounded, polished form is a cabochon, likely set in a small metal bezel.
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Physical properties
Hardness 6–6.5 Mohs; gray to dark gray body with blue-green iridescent labradorescence, vitreous luster, triclinic crystal structure, and two good cleavage directions. The rounded, polished form is a cabochon, likely set in a small metal bezel.
Formation & geological history
Forms in mafic igneous rocks such as basalt, gabbro, and anorthosite as calcium-rich plagioclase crystallizes from magma. Most gem-quality material is associated with Precambrian anorthosite deposits, especially in Madagascar, Finland, Canada, and Norway.
Uses & applications
Used for cabochon jewelry, carvings, ornamental objects, and mineral collecting; strong blue flash increases desirability.
Geological facts
Its shifting color is caused by light interference from microscopic lamellae produced during feldspar exsolution and cooling. The visible blue sheen is best seen by tilting the stone under directional light.
Field identification & locations
Identify by gray translucent body, broad internal cleavage-like fractures, and directional blue flash; distinguish from moonstone by its darker body and stronger multicolor sheen. Avoid ultrasonic cleaners and harsh impacts because of cleavage.
