Desert Varnish, What Is It? How Is It Used In Stone Carving?
Desert Varnish is the dark coating on rocks originally thought to be found only on stone in arid regions. Actually it occurs worldwide and in many environments, varnishes may even exist on Mars as suggested by observations on both the Viking and Mars Pathfinder landing sites. Desert Varnish occurs in many different colors and densities, from a glossy black, all shades of brown and some with orange tints. How is the varnish made? What is it composed of? How do I use this knowledge in my hand carved stone wall art? Initially it was thought that the varnish was created by substances being drawn out of the rock, a weathering of the stone or a chemical reaction changing actual surface of the stone. Further investigation shows however that the varnish has high concentrations of clay which could only come from the outside of the stone. The clay then catches additional substances that have a chemical reaction under the heat of the sun along with a little moisture from the air mixed in to make