I believe the orange beads are spondylus (spiny oyster) shell. The shells are quite common in old (and contemporary) Native North American ("Indian") jewelry as well as adornments from Peru.

The material and the stringing in your necklace is almost identical to "pre-Columbian" necklaces that I bought in Peru in the late 1970's and again more recently. These are very cool, but not terribly rare.