Here is a terrifc cabochon of native copper, hailing from Arizona. It has sections of copper along with cuprite all thoughout the cab. The back side view clearly illustrates the high percentage of copper going through the stone.
Although this one is a cabochon (or cab), you can also glue on "bails", or have the piece drilled to accept a pinch bail. Either approach will let you turn this sample into a fine pendant.