U. S. GEOLOGICAL SURVEY 
BULLETIN NO. 136 PL. XI 
ACID BRECCIA, RACCOON CREEK 
Natural size. The photograph does not bring out clearly the brecciated character of the work, which is 
very pronounced in the specimen. The matrix is apparently an ash containing angular fragments of a larger 
size (average diameter 1 cm.). The colors are blue, gray, and buff. 
