on the Geological Survey of South Carolina. 65 



diamonds have been discovered at the gold workings in this 

 itacolumite formation. 



Iron ores. — The magnetic oxyd, the specular oxyd, and the 

 hydrous peroxyd of iron, are all found ill the talcose and mica 

 slates of some of the districts. The ore Mr. Tuomey thinks 

 cotemporaneous with the slates, being frequently so intermingled 

 with them, as to prevent their being readily distinguished one 

 from the other. In examining one of the beds of specular iron, 

 he comes to the conclusion that it was originally sulphuret of 

 iron, and in connection makes the following remarks, which are 

 worthy of notice. 



"It is not a little curious that pyrites will resist decomposition 

 when placed under water, while, if it be exposed to the atmos- 

 phere, it is readily acted upon and reduced to an oxyd. Nearly 

 every gold mine in the state offers examples in illustration of this 

 fact. For wherever oxyd of iron is found mingled with the 

 ores, when water is reached, it is invariably found in the form of 

 iron pyrites. 



"We have first the sulphuret, or iron pyrites, which by decom- 

 position becomes probably the protoxyd, a portion of which 

 combines with another atom of oxygen, and forms peroxyd, the 

 mixture of the two now existing together, producing the magnetic 

 oxyd. The remaining protoxyd is converted into peroxyd, and 

 the whole is now the specular oxyd or red ore, which we find 

 towards the surface. And when during this change water enters 

 into combination with the ore, we have the hydrous peroxyd 

 or brown hematite ore. Every step in this progress may be ob- 

 served at the furnace bed, on People's creek." 



M. Tuomey states that, with a single exception, he nowhere 

 observed iron ore in a true vein. Here the ore was fibrous he- 

 matite, and was traced by him for miles. 



Gold. — The gold formation, the circumstances under which 

 gold is found, the mines which are explored, and the methods 

 adopted for working the ores, receive from our author particular 

 attention. We must, however, be brief in our notice of this as 



Wel1 as other portions of the work. 



After stating that the gold formation of the United States is 

 confined to a band of schistose rocks extending from the Rappa- 

 hannock in Virginia to the Coosa river in Alabama, Mr. Tuo- 

 tfjey remarks that these rocks in South Carolina, as well as in 

 the neighboring states, seldom exceed a breadth of sixty or 

 ei ghty miles, and that the gold is found at times in veins of gran- 

 ge, syenite, gneiss, hornblende and mica slates, as well as in the 

 talcose rocks, which have been considered the only gold bearing 

 rocks. He speaks of two classes of mines which are explored ; 

 the vein mines, where the metal occurs in the solid rock, and 

 the deposit or branch mines, consisting of beds of gravel and 



Second Series, Vol. VTJ r, No. 12.— July, 1 84 9. 9 



