COLOR

Leaves are green, the sky is blue, and little wagons are red. When we first learn the concept of color, we have little inkling of the hidden magic that creates it. Color is an interplay between microscopic structure and light. In minerals, color can tell many stories. Though not reliable for identification on its own, color can hone the accuracy of other identification tools. It can reveal a specimen’s composition, its origin, and even chemical reactions otherwise invisible under any but the most powerful of microscopes. In addition, trace chemicals in crystals can create a rainbow of color variations. Red and green tinted sediment can indicate rust reactions, rendering micro-chemistry visible from great distance, even from space—orbiting astronauts can make out the red hues of the rocks that make up Utah’s Arches National Monument. Special color effects, such as opalescence, reveal the microscopic structure of the specimen from which they emit. Though each of us learns basic colors in childhood, for those who pursue science, color is a realm of continuing discovery.