igneous

Larvikite

Monzonite (intermediate intrusive igneous rock containing plagioclase, alkali feldspar, augite, and biotite)

Hardness: 6-6.5; Color: Dark grey, charcoal, or bluish-black; Luster: Vitreous to sub-metallic; Crystal Structure: Monoclinic; Cleavage: Good; Specific Gravity: 2.59–2.63. It is characterized by an internal iridescent blue/silver reflection known as the Schiller effect.

Hardness: 6-6
Color: Dark grey, charcoal, or bluish-black
Luster: Vitreous to sub-metallic

Identified March 13, 2026More igneous →

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Physical properties

Formation & geological history

Formed at great depths (plutonic) from the cooling of magma approximately 292–298 million years ago during the Permian period. It is specifically associated with the Oslo Rift in Norway.

Uses & applications

Used extensively in architecture for building facades (notably the United Nations building), kitchen countertops, and monument stones. It is also popular in jewelry as beads and cabochons due to its labradorescence.

Geological facts

Often misidentified as 'Black Moonstone' or 'Blue Pearl Granite.' It is the National Stone of Norway. Unlike true Granite, it contains little to no quartz.

Field identification & locations

Identify in the field by its distinctive 'labradorescence' or 'Schiller effect'—a flash of blue or silver light when the dark stone is rotated. Primary locations include the Larvik region in Norway. Collectors should look for high-contrast flashes of color against the dark matrix.

Other igneous specimens

See all

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

Blue Apatite

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

mineral

Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

mineral

Magnetite

Magnetite (Fe3O4)

mineral