Clastic sedimentary rocks are formed from rock fragments or clasts; chemical sedimentary rocks precipitate from fluids, and biochemical sedimentary rocks form as precipitation from living organisms.
Sedimentary rock is classified into two groups based on how they form. They are clastic and chemical. Clastic sedimentary rock is formed as bits of weathered rock become cemented together. Because all kinds of rock are subject to weathering many different minerals can make up this group of rocks.