28 THE IRON ORE DISTRICT OP EAST TEXAS. 



and the deposits directly referrable to that period have not yet received suffi- 

 cient study to enable us to do more than indicate their existence and desig- 

 nate some of the members. The iron ores are in part at least of this period, 

 while the overlying quartzitic and quartzose sandstones and gray, yellow, or 

 buff-colored sands, together with some of the mottled sands or sandy clays 

 and gravel, certainly belong to it. 



THE ORES AND. THEIR MODE OF OCCURRENCE. 



The mode of occurrence and the association of the iron ores differ consid- 

 erably in the different districts, and therefore for the sake of convenience in 

 description, they have been grouped under three different headings, and will 

 be treated separately. 



1. Brown Laminated Ores. 



2. Nodular or G-eode Ores. 



3. Conglomerate Ores. 



1. BROWN LAMINATED ORES. 



"These ores are extensively developed south of the Sabine River, especially 

 in the counties of Cherokee, Anderson, Smith, Rusk, Harrison, Panola, Nacog- 

 doches, and Shelby. The extension of this belt to the southwest across the 

 Trinity River also remains to be examined. 



" The ore is a brown hematite of a rich chestnut color, and often of a highly 

 resinous lustre. In structure it varies from a compact, massive variety show- 

 ing no structure, to a highly laminated form, the laminae varying from one- 

 sixteenth inch to one-quarter inch thick, frequently separated by hollow spaces, 

 and sometimes containing thin seams of gray clay. These often give it a 

 buff color and a crumbly nature, and hence the name often applied to it of 

 'Buff Crumbly Ore.' The laminae frequently show a black glossy surface, 

 though the interior is always the characteristic rich chestnut brown color. 



" The ore occurs in a horizontal bed from one to three feet thick, and aver- 

 ages between eighteen inches and two feet in thickness. It is flat on top, but 

 is bulging and mammillary below and lies at or near the summits of the high- 

 est hills in the region. In fact, it is to this protecting cap of hard material 

 that the hills owe their existence, as it has saved the underlying soft strata 

 from the effects of erosion, which otherwise would quickly have lowered them 

 to the level of the surrounding rolling country. The iron ere bed is directly 

 underlaid by a deposit varying from thirty to forty feet thick of a soft yel- 

 low indurated glauconite (greensand). This bed is sometimes hardened into 

 a soft rock, easily cut with a saw or axe, and locally used as a building stone. 

 The interior of the bed, however, where it has not been exposed to the atmos- 



