mineral
Polished labradorite sphere
Labradorite, calcic plagioclase feldspar ((Ca,Na)(Al,Si)₄O₈)
AI-generated identification · may be incorrectGray-green, polished surface with visible internal cleavage and possible subtle blue-green labradorescence; vitreous luster, triclinic crystal structure, two good cleavage directions, Mohs hardness 6–6.5, specific gravity about 2.68–2.72.
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Physical properties
Gray-green, polished surface with visible internal cleavage and possible subtle blue-green labradorescence; vitreous luster, triclinic crystal structure, two good cleavage directions, Mohs hardness 6–6.5, specific gravity about 2.68–2.72.
Formation & geological history
Forms as an igneous mineral in mafic to intermediate rocks such as basalt, gabbro, and anorthosite when molten material cools slowly. Important deposits formed in Precambrian terrains, especially Madagascar, Finland, Canada, Norway, and Ukraine.
Uses & applications
Cut into cabochons, beads, spheres, carvings, and ornamental objects; also used occasionally as decorative architectural stone. This specimen’s value depends mainly on the strength and color of its flash.
Geological facts
Labradorescence results from light interference in microscopic intergrowths within the feldspar. Strong blue, green, gold, or multicolor flashes are most desirable.
Field identification & locations
Identify it by gray body color, feldspar-like cleavage, hardness near 6, and colored flashes that appear when rotated under a strong light. A glassy polish and lack of bubbles help distinguish it from man-made glass.
