| The clay layers are mainly composed of organic matter, clay minerals, quartz, feldspars, ankerite, pyrite, etc. |
| Calcite and ankerite are present, but the most abundant carbonate is magnesite. |
| Skeletal feldspar grains contain ankerite rhombs, and tiny sphalerite, galena, barite, and siderite crystals. |
| The crystals are of quartz, less often of calcite or dolomite, and sometimes of aragonite, ankerite, hematite, magnetite, pyrite, chalcopyrite, and sphalerite. |
| Nevertheless, it is supposed that nickel and cobalt form seams within ankerite and siderite blocks. |
| Other carbonates, i.e., ankerite, siderite, witherite, strontianite, may form if the respective metal cations are available. |
