Solid, the material is made from the quad shader. It’s actually a revamp of Jantim’s ZB2 metal shader from a few years ago. It might be possible to do a ZB3 version as a matcap combined in a doubleshader with another basic material, but I’m not sure. I still have to see if I can get this rusty iron material to work in ZBrush 3. These renders of the horse head were done in ZBrush 2.
Threetails, I’ll be uploading a set of materials soon. Some quad shaders and some matcaps. The skin shader I used for Nerve will be included. I’ll try to get a small tutorial together for it as well. It works well for various lighting situations, but the light settings (such as aperture and the intensity curve) really effect the translucent look of it as well, so I’ll try to explain everything when I upload it all. 
Here’s a couple other angles of the horse head.
