Explanation
A dark hard sandstone. The colors are gray, grayish green, grayish black, etc. It is composed of angular quartze, feldspar, mica and rock debris, and is poorly sorted. The content of impurities in rock is more than 15%, and they have been recrystallized, forming hydromica, chlorite, seridte and other minerals. Beautiful patterns can be used as ornamental stones (pattern stones).
Classification
Natural materials and products -> Mineral materials