Pfeiffer Beach at Big Sur, California, has distinctive areas of purple sand, which are mostly grains of reddish-purple manganese garnet crystals.
Garnet is a commonly-found mineral in beach sand, but usually at relatively low quantities. Pfeiffer Beach is notable because of the abundance of garnet minerals in the sand which give it a distinctive purple color.
These garnets likely originated in the rocks of the nearby Santa Lucia mountains. Over thousands of years, erosion caused rock fragments to break away and be transported to the ocean by the rivers. Erosion over time will have worn these rock granules down until only tiny grains of the most erosion-resistant hard minerals, such as garnet, remain. Waves and currents wash these garnets onto Pfeiffer Beach, and as it is a relatively heavy mineral it tends to settle in concentrated patches on the beach.
