SplendidSands

   The seaside resort town of Bretignolles lies along the southernmost coast of Brittany on France’s Atlantic shoreline. These beautiful sand grains are gemstones, and they congregate in waves and swaths on the beach. Winnowed by wave and tidal action, they segregate out from the quartz grains because they are “heavy minerals,” minerals with a higher density than quartz.

   The sand is sprinkled with sparking blue sapphires, the aluminum oxide mineral corundum. Some pink and red grains are ruby, red corundum; others are garnet, a mineral that can vary in color. Some black grains are magnetite, others are likely spinel, both iron-bearing minerals. The green grain, near center, is epidote; the yellowish grains with the near 90° corners are K-feldspar. Adding to the sparkle in this sample is clear quartz.

   Well rounded and polished, this characteristic of sand grains is indicative of a high-energy coastline where waves perpetually pound the shore. And the sand grains, in non-stop motion, rub, round and polish each other.