whitish opaque? Most random white stones you find at the beach are weathered quartz. Scratches and microscopic fluid inclusions account for the color. -- Even if they are away from the beach, these kinds of stones are frequently weathered out quartz veins. They are deposited by high temp. (200-600C) hydrothermal fluids. As the crystals grow, microscopic drops of this hydrothermal brine are trapped within the crystal, scattering light and giving it a white color.
