Pyramid Island is a very small island near the southeastern shore of Pyramid Lake, Nevada

Nevada

Nevada is a state in the western, mountain west, and southwestern regions of the United States. With an area of and a population of about 2.7 million, it is the 7th-largest and 35th-most populous state. Over two-thirds of Nevada's people live in the Las Vegas metropolitan area, which contains its...

. It is located approximately 1.2 miles northeast of Anaho Island

Anaho Island

Anaho Island is an island in Pyramid Lake, Nevada, USA, on the Pyramid Lake Indian Reservation. It is located in the southeastern part of the lake, approximately four miles east of the community of Sutcliffe...

 and slightly less than six miles from the community of Sutcliffe.
The white band seen to the east of the island is composed of calcium carbonate

Calcium carbonate

Calcium carbonate is a chemical compound with the formula CaCO3. It is a common substance found in rocks in all parts of the world, and is the main component of shells of marine organisms, snails, coal balls, pearls, and eggshells. Calcium carbonate is the active ingredient in agricultural lime,...

which came from when the lake was at or near its overflow point.