igneous
Labradorite (Larvikite variety)
Plagioclase Feldspar (Na,Ca)(Si,Al)4O8
Hardness: 6-6.5 Mohs. Color: dark grey to black with blue or silver flashes (labradorescence). Luster: vitreous to pearly. Crystal structure: triclinic. Cleavage: perfect in two directions.
- Hardness
- 6-6
- Luster
- vitreous to pearly
Identified More igneous →
Explore Labradorite (Larvikite variety) in the encyclopedia →Identify your own rocks.
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Physical properties
Hardness: 6-6.5 Mohs. Color: dark grey to black with blue or silver flashes (labradorescence). Luster: vitreous to pearly. Crystal structure: triclinic. Cleavage: perfect in two directions.
Formation & geological history
Forms in mafic igneous rocks through slow cooling of magma within the Earth's crust. Most high-quality specimens, like the Larvikite shown here, are from the Permian period approximately 290 million years ago.
Uses & applications
Used extensively in jewelry for its iridescent qualities, as well as interior design for countertops, tiles, and high-end architectural cladding.
Geological facts
The iridescent effect is known as 'labradorescence' or 'Schiller effect,' caused by light diffracting between microscopic layers of different mineral compositions within the stone.
Field identification & locations
Identify by rotating it under a light source to find the metallic 'flash' or blue/silver sheen. Found commonly in Norway (Larvik region), Madagascar, and Canada (Labrador).
