BY STEVE VOYNICK
Limestone is a great fossil medium; this fossil slab shows many forms of Devonian Period marine life.
In the world of sedimentary rocks that includes sandstone, siltstone, mudstone, shale and all intermediate grades, limestone is the star of the show. Although this fine-grained, often non-descript, grayish rock makes up only 10 percent of all sedimentary rock, it serves as an architectural stone and a vital material for the production of steel, chemicals, and cement. It is also an abundant source of fossils, the geological precursor of marble, and the host rock for the world’s great caves.