what kind of leather is this

[cowboy316]

hey guys i just went to work on the iris carving and noticed in the cuts where i beveled and the spots where i pear shaded and the backgrounding it seem to be oozing and oily type goo in all the years ive done leather work ive never seen this before and was wondering what kind of leather this is i wanna say its an oil tanned of some kind 
  Cowboy316