REPORT OF THE STATE GEOLOGIST. xlili 



existing in places in this district, has not yet been studied. This de- 

 scription is therefore confined to the different limonite ores. These 

 limonites are of three forms : 



Brown laminated ores. 



Nodular or geode ores. 



Conglomerate ores. 



The first of these is the usual ore of the iron district south of the 

 Sabine River, while the other two are principally found north of that 

 stream. The origin of these different varieties of ore is reasonably well 

 established by the investigations of the Survey. The beds of lamin- 

 ated ore are the results of the decomposition in place of iron pyrites, 

 greensand marls, and the carbonate of lime of the included shells, 

 the chemical action producing peroxide of iron, gypsum, and carbonic 

 acid. The nodular or geode ores are probably derived from the older 

 clay ironstones, while the conglomerate ores are but the results of the 

 partial breaking up and re-cementing of other ores. 



The laminated ores occur as beds of varying thickness, probably av- 

 eraging about two feet at the tops of the hills, which are the remains of 

 the ancient table lands of Eastern Texas, and are overlaid by sands of 

 variable thickness, or in many cases bv sandstone instead. This distri- 

 bution is not entirely uniform, as they are present in some hills and 

 absent from others, according to the existence or non-existence of con- 

 ditions favorable to their formation. They are, however, abundant and 

 rich, and are found in all gradations, from massive to coarsely laminated 

 structure. In color they are rich brown, often black, and are found in 

 many places throughout the counties lying below the Sabine River, at 

 least as far south as Sabine County, and west to and beyond the Trinity 

 River, but their extension west of that stream has not yet been traced. 

 From our present knowledge of their composition, we can say that there 

 are very few places where the ores are found in sufficient quantity for 

 iron making (other conditions being favorable) at which the quality of 

 ore is not good enough to warrant the erection of iron works. 



The nodular or geode ores, although very similar to the laminated 

 ores in their composition, differ widely from them in their mode of 

 occurrence. They appear principally in the counties north of the Sa- 

 bine River, in the shape of nodules or geodes, and of various forms of 

 honeycombed, stalactitic, botryoidal, or mammillary structure. They 

 vary in color from yellow to red, and sometimes a glossy black. These 

 nodules or geodes occur in deposits of variable extent, at times as de- 



