Onyx is banded agate displaying straight and parallel bands of alternating colors. It belongs to the Chalcedony family of quartz and comes in a surprising array of natural colors including the translucent greens and red and golden browns of these lovely spheres. These spheres have strikingly varied coloring, appearing to be several spheres in one simply by changing the viewing angle.  Beautifully polished 4" sphere from India. The Medium Brass Stand is sold separately.