Hornfels буталсан базальт боржингийн нягтшил
Hornfels Rock Formation, Properties, Uses and Occurrence … Hornfels; Hornfels is a fine grained metamorphic rock and It is the group for a series of contact metamorphic rocks that have been baked under high temperatures by the heat of igneous intrusions and as a result, have become massive, splintery, extremely hard, and in some cases exceedingly tough …