Olivine sand

Olivine sand is a rare sub-type of heavy mineral sand and also of volcanic sand. Olivine is important rock forming mineral and major component of mafic (rich in magnesium and iron) and especially ultramafic igneous rocks but it is rare in sand. There is one very good reason – it is very unstable in atmospheric conditions and decays quickly.

Good olivine containing sands can be found in Hawaii because basaltic lava, which makes up these islands, is rich in this mineral. There is one beach in Hawaii Island which is composed mainly of olivine. It is Papakolea on the southern tip of the island. Olivine is denser than other common minerals there and that allows waves to separate it from the rest and concentrate it on the beach. Source material for olivine is cinder cone which is situated right next to the beach.