A granite stone with numerous mottled colors in a wavy pattern than can resemble a rainbow. Rainbow granite quarried in Morton, Minnesota, has a dark black or green background with pink, yellow and red crystals producing a variegated pattern (Brady 1971). Another type, called African Rainbow Granite, is quarried in Nambia and has a white to ivory background with mutiple color pink and blue veins.
G.S.Brady, Materials Handbook, 10th edition, McGraw-Hill, New York, 1971.
Martus Stone at https://www.martusstone.com/product/rainbow-granite/
MSI Surfaces at https://www.msisurfaces.com/granite/african-rainbow/