set of various dark unpolished rocks with names

andesite background basalt black chromite coal collage collection cutout description flint gabbro gagate gemstone glass gneiss hematite hyalobasalt isolated jet kidney ludwigite magnetite mineral molybdenite name natural nepheline obsidian peridotite perovskite psilomelane psilomelanite raw rock rough schorl schungite set shale shungite slate sphalerite stone syenite tourmaline unpolished various vivianite volcanic white