The sand Dunes of Colorado are natures wonder and also a wonder when seen from space. The characteristic greenish black color areas of the sand dunes are due to the black sand. The characteristic black dunes appearing as green algal mass. This black sand is the deposits of magnetite that is a crystalline black oxide of iron. The peak of the dunes are said to be moist always. This feature is better reasoned by the misty looking deposits on the dunes. This image was created using the data supplied by the Global Land Cover Facility of the University of Maryland.