Why is Pingtan Jingsha black?

Pingtan mirror sand is black. Pingtan mirror sand is black because of the particularity of geological structure on the island and the formation of the beach itself. Pingtan Island is a small island located in a volcanic area with special soil. The sediments naturally accumulated on Jingshan beach also have the unique black and texture of volcanic rocks. In addition, the passivation and oxidation of the beach itself will also make the sand black. Therefore, the reason why Jingsha in Pingtan is dark is because of the particularity of the island's geological structure and the formation of the beach itself.