Bone is usually cattle shin bone. It has a different texture than antler (stag). Stag is usually from European or asian deer or elk species, though some modern makers are using North American elk or even whitetail deer antler. The most popular stag is Sambar stag. It is more dense than the domestic antler. Most pre-1960 Schrade Walden (and Schrade Cut Co) knives were bone jigged to resemble stag, or with other textures such as sawcut, a few smooth, and quite a bit with patterns from Rogers Manufacturing Company of Rockfall, Connecticut. They began making jigged knife handle material from domestic cattle bone around the turn of the century, but most of it came from Argentina by the 1920's. During WWII they sourced the bone also in Brazil and... the best, toughest bone came from old (15 yr) Australian range cattle.
At first, all the jigging was done by hand. Eventually they used machines. George Schrade patented a machine to do this in 1925 and cutleries which made their own handles (Camillus among them) began using George's machines. Rogers produced some distinctive patterns. I often see it stated that "Rogers Bone burned in 1956 and went out of business", but that is a myth. They may have suffered a fire, but last produced bone knife handles through 1962, gradually shifting to molding plastics, Delrin knife handles when the Dupont factory in Parkersburg, West Virginia was completed in 1960. By then, they had been doing plastics molding for five years or so. They continue in that business to this day.
Delrin is an acetyl resin of Nylon, but a lot of other plastics were used prior. More research is in order, but Dupont patented Delrin in 1956, so it is possible that limited quantities were available before 1960. Other types of Nylon and styrene were definately used.
So there is more than you ever wanted to know about stag jigged bone which Schrade often called simply "stagged" regardless of the particular pattern of jigging.
Michael