Well I didn’t know that. This is Fordite, or Motor Agate, an entirely man-made material, formed in car factories from layers of old automobile paint that dripped onto the metal racks which transported cars through the paint shop and into the oven. The paint was hardened to a rock-like state by the intense heat, with some paint undergoing over 100 bakings, and eventually became too thick, requiring removal. The following images show just what beautiful patterns some of the layers of paint formed, and pieces are now polished like gemstones to produce stunning art objects and jewellery. Some of this can be found over at:
It is also possible to date pieces of Fordite through the grouping and appearance of colours in the material, with some pieces having taken many decades to form.