THE NONMETALLIC MINERALS. 465 



try, but are exported to nearly all parts of the civilized world. Some of the finest- 

 grained material is also used in the manufacture of whetstones. There are various 

 points in the system of the Berea grit where the stone is adapted to this use, but sucli 

 a manufacture is best carried on when joined with a large interest in quarrying, so 

 that tlie small amount of suitable material can be selected; and thus it happens that 

 only at Amherst and at Berea are whetstones manufactured in large quantities. 



Below are given in brief outline the sources and main characteristics 

 of the principal grindstones now in the market, beginning with those 

 of the United States. In speaking of the texture of any stone, that of 

 Berea has been taken as the standard. This is the stone most used for 

 grinding cutting tools, such as axes and scythes. It must be remarked 

 here that the term Berea grit is applied not merely to the stone from 

 the immediate vicinity of the town of Berea, but is rather a general 

 name applied to this particular subdivision of the Subcarboniferous 

 formation of Ohio and extending over a wide field. 



Berea. — Medium fine; blue gray, light yellowish, or nearly white. 

 For edge tools in general; the finer varieties also used for whetstones. 

 Four quarries a few miles west of Berea produced alone upward of 

 $10,000 worth of grindstones during the last census year. (Specimen 

 No. 25059, U.S.N.M.) 



Amherst. — Medium fine, like the Berea, being a part of the same 



formation. Light gray, with small rust-colored spots due to iron 



oxides. For grindstones and whetstones for edge tools in general; 



the softer varieties for saws. (Specimens Nos. 25079, 25421, U.S.N.M.) 



Independence. — Similar to the Amherst, and especially adapted for 



the manufacture of large grindstones for dry grinding; stones said not 



to glaze when used for this purpose. (Specimen No. 25080, U.S.N.M.) 



Bedford. — Rather coarser, though of even texture and filled with 



brown spots of iron oxide. Especially adapted for grinding springs. 



Euclid. — Fine, light bluish-gray; for wet grinding edge tools. 



Massillon. — Medium to rather coarse; the microscope shows it to be 



an aggregate of rounded, colorless grains of quartz, with little, if any, 



cementing material. Not so finel}^ compacted as the last, and small 



fragments can be readily broken from the sharp edges by means of the 



thumb and fingers. Color, light yellowish or pinkish; for edge tools, 



springs, files, and nail cutters' face stones, but mainly for the dry 



grinding of castings. (Specimens Nos. 25054, 25055, U.S.N.M.) 



Constitution. — Medium; light gray and rather more fria])le than 

 the last. A variety of textures, however, and all kinds of grits for 

 wet grinding are furnished. (Specimens Nos. 25056, 25057, U.S.N.M.) 

 Huron., Michigan. — x^"'ine; uniform blue-gray color, with numerous 

 flecks of silvery mica. Smells strongly of clay when breathed upon. 

 For wet grinding of edge tools; produces a fine edge. (Specimen No. 

 25076, U.S.N.M.) 



The Jog gins., Nova Scotia. — Fine gray; of uniform texture; used for 

 wet grinding all kinds of edge tools; the larger stones for grinding 

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