While most of this specimen is siliceous, the small tan area on the broken face is calcareous. It is hard to tell for sure, but the colorful area on the broken face looks very much like gem bone. There are other features that may also be inclusions. Additional photos of these areas will be added at a later date. That said, it is really hard to tell if this is indeed a coprolite, but it has more promise than most I have seen from the Morrison Formation.
Please Note: Most rocks sold as coprolites from the Morrison Formation in Utah are likely not coprolites at all. Without the presence of inclusions or backfilled burrows left by dung eating insects, there is no way to verify that so called "agatized coprolites" have fecal origins. For this reason, I usually classify specimens of this type as dubiocoprolites.