What are rock sediments?

Answer 1

There are organic rocks, like Limestone, and clastic (composed of fragments), like Sandstone. Within these groups there are others, like coal is organic and siltstone is clastic, but even within limestone and sandstone, there are further categories. There's oolitic limestone, chalk and 'shelly' limestones; and arkose, desert sandstone, orthoquartzite (generic sandstone), and others. Conglomerate is an interesting one, if you are after a rock that is not 'normal'.