SciShow Rocks Box: Labradorite Palm Stone

Location: Madagascar Chemical Formula: (Ca,Na,)(Al2Si)4O8 Mohs Hardness Scale: 6-6.5 What do morpho butterflies, the back of DVDs, and this mineral have in common? Structural pigment! This labradorite stone gets its incredible blue-green flash thanks to a phenomenon called labradorescence. The layers that make up this stone have different refractive indices, meaning light bends differently as it passes through. Those bouncing light waves interact with each other and by the time they get back to our eyeballs, they look like, well, this! And the story of those layers’ formation took place over millions of years. When the island of Madagascar was forming, intrusions of magma kept trying to reach the surface, but the crust was so thick that these pockets couldn’t burst through. This caused that magma to cool down slowly and settle into layers, like oil and water, giving us these stunning stones.