Where is actual texture most often found?

Actual texture as opposed to visual texture is the materials used to create a work of art. Actual texture is physical it's hard, cold,smooth, etc. Impasto is an actual texture technique.  

Texture is one of the most fundamental elements of three dimensional art. It is an element that needs to be carefully considered by sculptors. Texture is related to the material used--marble, wood, clay, bronze, brass, iron. steel, or plaster, for example-- as well as the process: casting, carving, construction, or welding. In addition to the material and the process, the final surface treatment offers even more textural possibilities. These include patination (chemically altering the surface of metal), painting, staining, bleaching, varnishing, polishing, waxing, sanding, buffing, scorching, tapping the sufrace with various tools to add texture, and using a grinder to smooth out rough textures and welding seams, among other things.