igneous
Labradorite (in Larvikite or Gabbro)
Plagioclase Feldspar (containing (Ca, Na)(Al, Si)4O8)
Hardness: 6-6.5 Mohs. Color: dark gray to black matrix with iridescent blue flashes (labradorescence). Luster: vitreous to pearly. Crystal structure: triclinic. Cleavage: perfect in two directions.
- Hardness
- 6-6
- Luster
- vitreous to pearly
Identified More igneous →
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Physical properties
Hardness: 6-6.5 Mohs. Color: dark gray to black matrix with iridescent blue flashes (labradorescence). Luster: vitreous to pearly. Crystal structure: triclinic. Cleavage: perfect in two directions.
Formation & geological history
Formed through the slow crystallization of mafic igneous rocks like gabbro or norite deep within the Earth's crust. Slow cooling allows for the exsolution lamellae that create the iridescent play of color.
Uses & applications
Used primarily as decorative stone, countertops, floor tiles, and in jewelry (beads/cabochons). High aesthetic value in architectural cladding.
Geological facts
The iridescent effect is known as labradorescence; it is caused by light reflecting off microscopic layers of different feldspar minerals within the stone. It was first discovered in Labrador, Canada.
Field identification & locations
Identify by rotating under a light source to find the 'flash' of blue or green against a dull gray background. Commonly found in riverbeds or coastal areas near igneous outcrops in Canada, Norway, and Madagascar.
