242 



REPORT OF NATIONAL MUSEUM, 1899. 



1). Blue clay, about 6 inches thick. 



c. Paint ore, varying from 6 inches to 6 feet in thickness, 



d. Yellow clay, 6 feet thick; 



e. Oriskany sandstone, forming the crest and southern side of the 

 ridge. It is extremely friable, and disintegrates so readily that it is 

 worked for sand at many points. (See fig. 8.) 



The paint bed is not continuous throughout its extent. It is faulted 

 at several places; sometimes it is pinched out to a few inches, and again 

 increases in width to 6 feet. The ore is bluish-gray, resembling lime- 

 stone, and is very hard and com- 

 pact. The bed is of a lighter 

 tint, however, in the upper than 

 in the lower part, and this is 

 probabl}^ due to its containing 

 more hj^draulic cement in the 

 upper strata. The paint ore 

 contains partings of clay and 

 slate at various places. At the 

 Rutherford shaft there are fine 

 bands of ore alternating with 

 claj' and slate, as follows : Sand- 

 stone (hanging wall), clay, ore, 

 slate, ore, clay, ore, slate, ore, 

 cement, slate (foot wall). These 

 partings, however, are not con- 

 tinuous, but pinch out, leaving 

 the ore without the admixture 

 of clay and slate. Near the out- 

 crop the bed becomes brown 

 hematite, due to the leaching out 

 of the lime and to complete oxi- 

 dation. Occasionally streaks of 

 hematite are interleaved with 

 the paint ore. In driving up the 

 breasts toward the outcrop the 

 ore is found at the top in 

 rounded, partially oxidized, and weathered masses, called "bomb- 

 shells," covered with iron oxide and surrounded by a bluish clay. In 

 large pieces the ore shows a decided cleavage. 



Preparation. — As alreadv intimated, only a small portion of the 

 ocher is used in its natural condition, it being first roasted and then 

 ground, the grinding being either "dry" or in oil. The roasting 

 deepens the color to a degree dependent upon the length of time the 

 ore is exposed. Yellows are converted into browns and reds, and the 

 ocher rendered less hydrous at the same time. The crude ore as mined 



SECTION ACROSS THE BED. RUTHERFORD AND BARCLAY MINE. 



Fig. 8. 



SECTION ACROSS PAINT MINE AT LEHIGH GAP, PA. 



After C. E. Hesse. 



