Clastic sedimentary rocks are primarily formed from fragments of other rocks. These fragments, known as clasts, are produced through processes such as weathering and erosion, where larger rocks are broken down into smaller pieces. These clasts are then transported by wind, water, or ice and subsequently deposited in a new location. Over time, the accumulated sediments undergo compaction and cementation, resulting in the formation of clastic sedimentary rocks.
The key characteristic of clastic rocks is that their composition is directly derived from the physical breakdown of pre-existing rock material rather than the chemical precipitation of minerals or the accumulation of organic material. This distinguishes them from other types of sedimentary rocks, such as chemical sedimentary rocks, which are formed from soluble minerals that precipitate from water. Therefore, the primary component of clastic sedimentary rocks is indeed the pieces of other rocks.