Answer:
Yes, it could have been monazite.
Monazite could have become part of sedimentary rock because it is formed during the metamorphosim of clastic sedimentary rocks. It is a resistant minerals that is found in weathered rocks debris which become concentrated and they are part of the soils and sediments found near weathered rocks.
Explanation:
Monazites are phosphate minerals that are found im small grains as accessory in igneous rocks and sedimentary rocks. It is formed during the crystallization of igneous rock and metamorphosim of clastic sedimentary rocks.
It is a resistant minerals that found in weathered rocks debris and become concentrated in sediments near weathered rocks.