igneous

Labradorite (Larvikite variety)

Plagioclase Feldspar (Na,Ca)(Al,Si)4O8 with Monzonite/Syenite matrix

Hardness: 6.0-6.5; Color: Dark grey to black with blue/silver iridescent patches; Luster: Vitreous to pearly; Crystal structure: Triclinic; Specific gravity: 2.68-2.72; Cleavage: Perfect in two directions at nearly 90 degrees.

Hardness: 6
Color: Dark grey to black with blue/silver iridescent patches
Luster: Vitreous to pearly

Identified March 30, 2026More igneous →

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Physical properties

Formation & geological history

Formed from the slow cooling of magmatic melts deep in the Earth's crust (intrusive). The iridescent effect (labradorescence) is caused by light diffraction in regular layers of different compositions (lamellae) that develop during cooling.

Uses & applications

Used widely for architectural cladding, high-end kitchen countertops, monuments, and as a semi-precious gemstone for jewelry and decorative carvings.

Geological facts

This specific variety is often marketed as 'Blue Pearl Granite' even though it is geologically a Larvikite. It is the national stone of Norway. The labradorescence seen in the flashes of color is due to the Schiller effect.

Field identification & locations

Identify in the field by rotating the dark, coarse-grained rock under light to find the 'flash' of blue or silver. It is commonly found in the Larvik region of Norway and parts of Canada, Madagascar, and Russia.

Other igneous specimens

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Blue Apatite

Fluorapatite (Ca5(PO4)3F)

mineral

Dark Igneous Rock (Likely Basalt or Diabase)

Basalt (extrusive igneous rock) or Diabase (intrusive igneous rock - also known as Dolerite), largely composed of plagioclase feldspar, pyroxene (augite), and sometimes olivine and amphibole. Exact mineralogy would require thin section analysis.

Igneous

Magnetite

Iron(II,III) oxide (Fe3O4)

mineral

Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

mineral

Blue Apatite

Apatite (Group), Ca5(PO4)3(F,Cl,OH)

mineral

Magnetite

Magnetite (Fe3O4)

mineral