Name:  Oolitic limestone

Geologic Name:  Spergen Limestone

Reference:  Blatchley, R.S., The Indiana oolitic limestone industry in
1907: Indiana Dept. of Geol. and Nat. Resources, 32nd Ann. Rept.,
p. 301-460, 1907.

Microscopic characters:  The rock is composed of an aggregate of
oolites of calcite and microfossils.  They are cemented by a fine 
granular mass of calcite.  A small amount of ferrite occurs in small
flecks.