From a distance, the dunes at Great Sand Dunes National Park look barren. Some dark areas can be seen, but the dark sands are rich in magnetite, an oxide of iron, exposed when the wind churns and ...

Dust mites belong to the arthropod family. They’re related to ticks and resemble insects but lack wings and eyes. Dust mite reactions are typically harmless, though they can cause swelling, itching, ...