Hawaii's Green Sand Beach is made of rounded crystals of olivine, also known as peridot.
Gemstone-quality olivine (chrysolite) is called peridot. Olivine is one of the most common minerals. It is a magnesium iron silicate with the formula (Mg,Fe)2SiO4.
S Kitahashi, wikipedia.org
This is a gem born of fire, associated with lava. Peridot is one of the few gemstones that comes in only one color. The shade of green depends on the amount of iron in the crystal.