oolite
noun
oo·lite ˈō-ə-ˌlīt 
: a rock consisting of small round grains usually of calcium carbonate cemented together
oolitic
ˌō-ə-ˈli-tik
adjective 
Word History
Etymology
probably from French oolithe, from oo- o- + -lithe -lite
First Known Use
1785, in the meaning defined above