Ground, Soil, Texture, Granite, greywacke, graywacke, grey, earthy rock, variety of sandstone characterized by its dark color, poorly sorted angular grains, quartz, feldspar, small rock fragments, lithic fragments compact, clay-fine matrix, immature sedimentary rock Paleozoic strata, industrial usage, road construction, building material, Germany, Greywacke, gray, mineral, district, quartz glass, glass, germany, spar, european country, natural glass