Siesta Beach is a beach located on Siesta Key in the U.S. state of Florida. Unlike beaches elsewhere that are made up mostly of pulverized coral, Siesta Beach's sand is 99% quartz, most of which comes from the Appalachian Mountains. Over time the feldspar and mica have been removed from the rock, leaving almost pure quartz. Even on the hottest days, the sand is so reflective that it feels cool underfoot.