This is a polished labradorite slice from Madagascar. Only one side has been polished to accentuate the iridescent color changes, known as a schiller effect or 'labradorescence'. Labradorite is a type of feldspar mineral that contains twinning mineral structures that reflect light that enters in the mineral, causing the iridescence. You can find an many colors in labradorite's iridescence, with some pieces only reflecting a single color and others reflecting the entire rainbow!
You will receive a piece similar in size to the one pictured. The color variations may differ, but you will always receive a specimen that exhibits an iridescent shine! This piece is approximately 5cm x 4.5cm x 1cm.