mineral
Labradorite
(Ca, Na)(Al, Si)4O8 (Plagioclase Feldspar)
Hardness: 6-6.5 Mohs; Color: Gray to black with blue/green/gold iridescence; Luster: Vitreous to pearly; Crystal Structure: Triclinic; Cleavage: Perfect in two directions; Specific Gravity: 2.68-2.72
- Hardness
- 6-6
- Color
- Gray to black with blue/green/gold iridescence
- Luster
- Vitreous to pearly
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Physical properties
Hardness: 6-6.5 Mohs; Color: Gray to black with blue/green/gold iridescence; Luster: Vitreous to pearly; Crystal Structure: Triclinic; Cleavage: Perfect in two directions; Specific Gravity: 2.68-2.72
Formation & geological history
Forms in mafic igneous rocks like basalt, gabbro, and norite through the crystallization of cooling magma. Common in Precambrian rocks over 1 billion years old.
Uses & applications
Primarily used as a gemstone in jewelry, for decorative carvings, and as a countertop material (Labrador Antique granite).
Geological facts
Exhibits a unique optical effect known as labradorescence, caused by light diffracting from submicroscopic layers within the mineral. It is often called the 'Aurora Borealis' of stones.
Field identification & locations
Identify in the field by rotating the specimen to catch the metallic blue or green flashes (schiller effect) against a dark gray background. Found extensively in Labrador, Canada, and Madagascar.
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sedimentary
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Metamorphic
Epidote
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metamorphic
Gypsum (variety Selenite or Alabaster)
Calcium sulfate dihydrate (CaSO4·2H2O)
Mineral
Nephrite Jade
Nephrite
Mineral/Rock
Banded Gneiss (River Rock/Pebble)
Gneiss (specifically a banded variety often found as a river rock)
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