THE PETROGRAPHIC CHARACTER OF OHIO SANDS 
WITH RELATION TO THEIR ORIGIN" 
D. DALE CONDIT 
Geological Survey of Ohio, Columbus 
In connection with a report in preparation by the Geological 
Survey of Ohio on glass and molding sand, a petrographic examina- 
tion of a large number of samples was made by the writer of 
this paper. The samples were collected from all parts of Ohio 
and represent practically all the important deposits of the state 
from the oldest to the very recent. About ninety rock samples, 
Carboniferous and older, were examined, and forty uncemented, 
recent sands from the glacial drift and other sources. The petro- 
graphic work was done in the geological laboratories at Columbia 
University. 
In preparing the samples for inspection with the microscope, 
thin sections were made of the rocks. Most of these had only a 
slight bond so they were first boiled in Canada balsam until all the 
interstices were permeated by that liquid. On cooling there 
resulted a firmly cemented mass which would permit of grinding 
to the usual thickness. In the case of loose, uncemented sands, 
liquid mounts were made in oil of cloves which has an index refrac- 
tion similar to that of balsam. Many of the samples being made 
up of grains too thick for study with polarized light were first 
crushed to 1oo-mesh size in an agate mortar, after a preliminary 
inspection had been made to determine the shape and size of grain. 
The sands ordinarily met with in Ohio may be divided into 
three great groups on the basis of physical properties and mineral. 
make-up. The three groups are: (1) The old sandstone formations 
Permo-Carboniferous and older; (2) residuary and outwash 
deposits derived by weathering and erosion of the sandstones; 
(3) glacial drift sands—recent deposits made up of assorted material 
1 Published with permission of the State Geologist of Ohio. 
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