Sand, Puako Beach, Hawaii, Hawaii

This interference figure is a conoscopic view of a grain of olivine from a sand sample collected on Puako Beach on the Big Island of Hawaii. It is mounted in Cargille Melt Mount 1.68 refractive index medium. This is looking down one of the optic axeses. Circular polarized light removes the isogyres. The elliptical shape of the isochroms indicates a biaxial crystal and the position of the acute bisectorix, northeast of this view.