> I thought it was Kimberlite, but it is Peridotite according to the linked page.
>
> > Next question: What makes green sand green?
> > Howard

Well, no. Green dirt in Arkansas and green sand on Hawaii are two very different things. The surf is eroding an old lava flow on the south shore of Hawaii. That lava has a high content of olivine, a greenish mineral that is often extruded from volcanoes. Softer materials are washed away leaving bits of olivine.

The composition of lava is not always the same. It brings a variety of minerals to the surface.

Black sand and red sand in Hawaii are formed by a similar process, with different minerals. My favorite sand is the golden sand on Kauai, which is a combination of coral and lava. In a few places it is almost pink. They also have barking sand on Barking Sand Beach. It makes a little sound when you walk on it.
Howard