This rock contained chalcedonic cement before it underwent diagenesis, a process where low temperatures and low pressures alter the content of sediments before they finally lithify, or turn into rock.

• 在它经历成岩作用之前，它含有燧石质的胶结成分。成岩作用过程中，低温抵压改变了沉积物的成分，而后固结成岩。