"Harlequin opal" is a name given to an opal with patches of fire in the shape of rectangles or diamonds. The specimen at right is a harlequin opal from the Constellation Mine in Spencer, Idaho. It is 6 millimeters by 4 millimeters in size.
Find it on Geology.com
More from Geology.com
Ant Hill Garnets are tiny garnets that ants haul to the surface and discard on their anthill. Honest!