Jackson.] 



86 



facts relating to the segregation of the emery. Frequently large 

 globular masses of it arc found of uncommon purity separated from the 

 principal masses of the bed and surrounded by a thin layer of bright 

 green Chlorotoid, and a thicker layer of interwoven laminated crystals 

 of delicate lilac colored Margarite, sometimes tAvo or more inches in 

 thickness. These minerals, according to Dr. J. Lawrence Smith's 

 theory of the segregation of emery, are minerals of elimination, or 

 were thrown off by the segregating emery. Some of these balls 

 of emery are three feet or more in diameter, and arc extremely 

 difficult to break, for the sledge can get no gripe on the rounded sur- 

 faces, and it is almost impossible -to drill them. I therefore advised 

 the application of fire, which by irregularly expanding the masses will 

 cause them to break to pieces ; or, that they be cracked by means of a 

 heavy drop hammer, if it is desirable not to roast the emery. Expe- 

 riment shows, however, that the grain of the mineral is not injured 

 for practical use by any degree of heat applied to it. 



The following diagram represents a section of the rocks at the base 

 of the South Mountain. 



Beginning at the right or lower rocks we have 



1. Highly crystalline and brilliant black Hornblende Rock which 

 extends to the eastward for some distance, but how far is not known. 



2. A bed of magnetic Iron ore more or less impregnated with 

 emery. 



3. The emery bed with numerous strings and reticulated veins of 

 Margarite, Chlorotoid and black Tourmaline. This bed is here four 

 feet thick. 



4. A small bed of granular Quartzlte. 



5. Chlorite and Talcose slate mixed. 



6. Crystallized Talc. 



7. Talcose Slate rock. 



8. Soap Stone or Talcose rock. 



