igneous
Labradorite Granite (Blue Pearl)
Anorthosite (dominated by Labradorite feldspar)
Hardness: 6-6.5 (Mohs scale); Color: Steel blue to dark grey with iridescent blue flashes; Luster: Vitreous to pearly; Crystal structure: Triclinic; Cleavage: Two directions at nearly 90 degrees; Specific gravity: 2.68-2.72.
- Hardness
- 6-6
- Color
- Steel blue to dark grey with iridescent blue flashes
- Luster
- Vitreous to pearly
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Physical properties
Hardness: 6-6.5 (Mohs scale); Color: Steel blue to dark grey with iridescent blue flashes; Luster: Vitreous to pearly; Crystal structure: Triclinic; Cleavage: Two directions at nearly 90 degrees; Specific gravity: 2.68-2.72.
Formation & geological history
Formed from the slow cooling of magnesium and iron-rich magma deep within the Earth's crust (plutonic). This specific variety is famously quarried in the Larvik region of Norway (Larvikite) and dates back to the Permian period, approximately 298-250 million years ago.
Uses & applications
Widely used for high-end kitchen countertops, floor tiles, exterior building cladding, monuments, and decorative interior accents. Some high-quality pieces are used as gemstones for jewelry.
Geological facts
The striking blue shimmer is known as 'labradorescence,' caused by light reflecting off internal microscopic planes of different mineral compositions. While commercially called 'granite' in the stone industry, it is scientifically an anorthosite or larvikite.
Field identification & locations
Identify by the 'schiller' effect or blue flash when light hits the surface at certain angles. Commonly found in Norway, Canada, and Madagascar. In the field, look for a dark, coarse-grained rock that displays sudden metallic blue or silver sparks.
