Stone, Ralph W.  1876-1964. <br/><br/>
The minerals of Pennsylvania: Non-metallic minerals, 
by R. W. Stone. 
 - Harrisburg, Pa.,  Department of Internal Affairs, Topographic and Geologic Survey,  1939. 
 - 50 p. incl. illus. (map) tables.  23 cm. 
 - Bulletin M,  18-C .
<br/><br/> At head of title: Pennsylvania Geological survey, Fourth series  With Ashley, G. H. The undeveloped mineral resources of Pennsylvania. 1933. (Bulletin M18-A) 
<br/><br/>Bibliographical footnotes. 
<br/><br/><label>LCCN: </label>gs 40000143  
<br/><br/><label>Subjects--Topical Terms: </label><br/>Mines and mineral resources--Pennsylvania.
<br/><br/><label>LC Class. No.: </label>TN24.P4  / A7