Jordan - The Jordanian ḥarrah

Al- ḥarrah, or basalt desert, stretches from southern Syria across north-eastern Jordan into northern Saudi Arabia. Much of this area consists of broken-up lava flows which cover the desert floor with millions of basalt stones and boulders. As a result of the chemicals in the basalt interacting with those in the atmosphere the exposed parts of these rocks are covered with a thin patina (or “desert varnish”) which over millions of years has produced a shiny black surface. If this surface is pierced, the resulting mark shows the natural pumice-grey colour of the rock beneath, which looks almost white against the surrounding black. Over the millennia, this mark gradually patinates back to the black of its surroundings, at a speed dependant on the depth and width of the mark and the degree of exposure it suffers.