DESCRIPTION OF THE ORES 479 



from their original position, and are now found only in fragments inter- 

 mingled in the clay mass. The pipe ores have not been observed in the 

 sandstone or slate areas, but are abundant in limestone ore regions, in 

 some places forming the major part of the ore. 



BRECCIATED ORE 



The brecciated ore consists of fragments of chert, sandstone, or slate, 

 cemented by iron oxide into a solid mass. These masses are sometimes 

 quite large, many tons in weight, forming so-called solid ore bodies. 

 Frequently the inclosed rock fragments disintegrate and crumble out, 

 leaving the more or less cavernous skeleton of ore (see number 12, plate 

 50, figure 1). Brecciated ore is found on the limestones, on the clay, 

 and on the sand deposits. It occurs in large quantities on the sand de- 

 posits in the Nittany valley, where the greater part of the inclosed frag- 

 ments consists of chert from the overlying limestones. I have nowhere 

 observed any limestone fragments in any of the brecciated masses. It 

 is possible that some of the hollow spaces may represent former lime- 

 stone fragments which have all been leached out. The brecciated ores 

 are most abundant where the ore masses rest on the sandstone or inter- 

 calated clay beds, and while in general they are most abundant near the 

 bottom of the deposit, huge blocks of them are scattered at various levels 

 through the clay-ore mass. 



FLAKE VR SHEET ORE 



Flake or sheet ore occurs in the joint and bedding seams of the lime- 

 stone and slates. So far as it has been observed in situ it occurs in com- 

 paratively thin flaky laminated sheets, often less than an inch in thick- 

 ness (see figures 2 and 4). As the surrounding rock is leached away, 

 the ore sheets and flakes are carried down and more or less broken up 

 and mingled with the other materials. The nature of the ore fragments 

 observed in the residual clay shows this type of ore to be locally the 

 most abundant of all those mentioned, while in other localities it is al- 

 most entirely wanting. 



FRAGMENTAL ORE 



Fragmental ore consists of irregular angular fragments of all sizes 

 commingled with the residual clay, being probably in all cases broken 

 remnants of the preceding forms. It is not always possible, however, 

 to refer the fragment to its original form, as there is often no essential 

 difference in appearance between a small fragment of a sheet and that 

 of a pipe or a shell. In several localities, most noticeably in the lime- 

 stone districts, there are rounded water-worn fragments of the ore asso- 



