Igneous rocks are formed from the cooling of molten ... The granite is polished, so it moves quickly and smoothly across the ice. 2. Decorative uses Obsidian can be carved into decorative figures.

The Journal of Geology, Vol. 23, No. 8, Supplement: The Later Stages of the Evolution of the Igneous Rocks (Nov. - Dec., 1915), pp. 1-91 (91 pages) ...