The scientific name of this tiny cactus is Copiapoa cinerea. An extremely slow growing cactus, it seems as if this small specimen hasn't grown at all since I acquired it late last year. Eventually its purple color will change to a dull green, but the spines will remain the same dark color. One of the reasons it has a purple hue (other than its young age) is that I keep it in light shade. In Phoenix, it requires some summer sun protection even as it ages.
C. cinerea is native to northern Chile. There are about 20 other species and subspecies in this genera, and they are coveted for their rib formation. As this cactus grows, it will look nothing like it does in the photo. This species can reach about a foot tall and wide after many years. When I acquired it from a grower who specializes in cactus seed propagation, he referred to it as a 'gourmet' genus and species. I've seen members of this genus in cactus nurseries, but not often. Perhaps by 'gourmet', he meant semi-rare.
Eventually, this cactus will begin to offset. Most collectors remove the offsets so they will not detract from the cactus' basic form, which resembles a Golden Barrel. The flowers will be yellow.