Feldspar group (plagioclase)
Labradorite
That flash - labradorescence - is interference, not pigment. The stone separated as it cooled into extremely thin alternating lamellae of two feldspar compositions, and light reflecting off those internal layers interferes with itself, returning one narrow band of colour at one particular viewing angle.
- Mineral family
Feldspar group (plagioclase)
- Typical colours
Smoky grey to near-black body, flashing blue, teal, gold or green
- Hardness (Mohs)
6 - 6.5
- Luster
Vitreous to pearly on the flashing planes
- Texture
Dark and matte-looking until it is turned, when a flat plane of colour lights across the whole face and then disappears.
Caring for it
Feldspar again, so it cleaves and chips more readily than quartz. Store it separately, avoid knocks and ultrasonic cleaners, remove it before swimming, and clean with nothing more than a soft dry cloth.