White Sands is white primarily due to the exceptionally high purity of its gypsum sand.
The Reason Behind the Brilliant White
The stunning, pure white color characteristic of the White Sands dunes is a unique geological feature. This distinct hue isn't just a visual trait; it's directly linked to the composition and purity of the sand itself.
High Purity Gypsum
As highlighted by researchers, the white color is caused by the high levels of purity of the gypsum sand. Unlike other sands composed of various minerals that might give them darker or more varied colors (like brown, grey, or red), the gypsum crystals at White Sands are remarkably free from impurities like iron oxides or organic matter.
How Purity Creates Whiteness
The lack of these impurities is key to the sand's bright appearance:
- Pure substances often have predictable and strong interactions with light.
- The highly pure gypsum sand reflects and refracts light very effectively.
- This interaction occurs uniformly across the visible light spectrum.
- Instead of absorbing specific wavelengths of light (which would result in a colored appearance), the pure gypsum crystals scatter and bounce back almost all the light that hits them.
Essentially, this strong and uniform reflection and refraction of light, enabled by the sand's high purity, makes White Sands appear vibrantly white to our eyes. The individual gypsum crystals act like tiny prisms or mirrors, collectively creating the vast, blindingly white landscape.
