igneous
Larvikite (polished/tumbled)
Larvikite, a monzonitic alkaline intrusive rock; mainly alkali feldspar, plagioclase, and augite/other pyroxenes
AI-generated identification · may be incorrectDark gray to blue-gray, coarse crystalline, with pale feldspar patches and possible blue schiller (iridescence); granular texture and generally massive structure. Hardness is roughly 6–7 Mohs; cleavage belongs to constituent feldspars rather than the rock as a whole.
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Physical properties
Dark gray to blue-gray, coarse crystalline, with pale feldspar patches and possible blue schiller (iridescence); granular texture and generally massive structure. Hardness is roughly 6–7 Mohs; cleavage belongs to constituent feldspars rather than the rock as a whole.
Formation & geological history
Slow cooling of silica-undersaturated magma produced this intrusive igneous rock, chiefly in the Permian Oslo Rift of southeastern Norway, approximately 300 million years ago.
Uses & applications
Used as dimension stone, countertops, façades, flooring, monuments, and decorative tumbled specimens. It is commonly marketed as “Blue Pearl” or “Labradorite” granite, though it is not true granite or labradorite.
Geological facts
Its blue flash comes from light scattering within feldspar crystals, similar in appearance to labradorescence. The photograph strongly suggests larvikite, but exact identification would require a fresh surface, mineral testing, or petrographic analysis.
Field identification & locations
Look for a dense black-gray stone with interlocking pale feldspar crystals and blue-gray flashes when tilted under light; it is especially associated with Larvik, Norway. Test hardness and avoid relying solely on color, since similar gabbro and anorthosite can look alike.
