"Sunstones," at least the type from Oregon, can be strikingly beautiful. They feature a type of labradorite feldspar that contains copper in varying amounts. The best occur in saturate reds, greens or a combination of the two colors. Many show an optical effect called "schiller," an almost metallic sheen caused by nearly invisible aligned particles in the stones. The ones from India and Tanzania feature bright spangles, sometimes multicolored, resulting from light bouncing off crystal inclusions in the stones.
Go here for images of various sunstones: Sunstone Images