Larvikite has so many misleading names that it makes perfect sense that many people confuse it with Labradorite and Black Moonstone. These names include Black Labradorite, Black Moonstone, Norwegian Moonstone, and Blue Pearl Granite, just to name the most common. This video will show you a side by side comparison so that you can identify which you have, even if it was labeled as one of those “other” names.
Black Moonstone: 6-6.5
Black Moonstone: White
Larvikite: Larvikite is a Augite Syenite or Monzonite with relatively high Al2O3, Na2O and K2O contents. It is a relatively coarse-grained Anorthoclase-rich igneous rock. Anorthoclase constitutes 90 or more percent of this rock. The presence of the alternating Alkali Feldspar and Plagioclase layers give characteristic silver blue sheen (Schiller effect) on polished surfaces. (gemdat) Even though the main mineral in Larvikite is Feldspar, the rock type also contains some Olivine, Clinopyroxene, Amphibole, Biotite, Magnetite and Apatite. Sometimes there is also a little Nepheline present. Some of these minerals are dark, but Feldspar and Nepheline are lighter, and it is the variations in the content of the light and dark minerals that causes the layering. (geoparken.com) (Click here to read more about Larvikite.)
Labradorite: Labradorite is a Plagioclase Feldspar. It has the chemical composition of (Na,Ca)Al1-2Si3-2O8 (Sodium, Calcium, Aluminum, Silicon, Oxygen). (Click here to read more about Labradorite.)
Black Moonstone: Black Moonstone is an Orthoclase Feldspar. It has the chemical composition of KAlSi3O8 (Potassium, Aluminum, Silicon, Oxygen). (Click here to read more about Black Moonstone.)
► Don’t forget to check out my video and article comparing Moonstone and Rainbow Moonstone (aka White Labradorite).
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