Aragonite is a carbonate mineral, one of the two common, naturally occurring, crystal forms of calcium carbonate, CaCO3 (the other form being the mineral calcite). It is formed by biological and physical processes, including precipitation from marine
Thierry Cohen made these by combining the daylight pics of the cities and the pristine skyline of the desert at the same latitude, direction, and angle. He wants to show what city dwellers would see without all the light pollution