186 PROCEEDINGS OF THE ACADEMY OF [Part I 



Beyond this is the corundophihte zone^^ composed of plates of cor- 

 undophiUte 20 mm. broad, which may be wholly replaced by oligo- 

 clase. The corundophilite often penetrates the emery vein in 

 sheets filling fissures, on which may occur in cavities fine foliated 

 sheets of pearly margarite, and thick masses of interlaced blades 

 and crystals of violet diaspore, frequently enclosing bright red 

 needles of rutile, or broad plates of ilmenite.^^ Rarely associated 

 with these are radiating yellowish green needles of epidote, or brown 

 crystals of brookite. To a much later period of mineralization be- 

 long veins of specular hematite in small rosettes, pyrite, chalcopy- 

 rite, calcite, and aragonite. 



It will be seen that the mineralogy of this deposit is quite com- 

 plex. However, the presence of such minerals as tourmahne, oligo- 

 clase, rutile, brookite, etc., the evidence of reaction with the serpen- 

 tine, and the features resembling the plumasites described above, 

 all indicate that this deposit probably owes its origin largely to the 

 desilication of a granitic pegmatite intruded along the contact of 

 the hornblende schist and serpentine. 



Georgia: The Georgia corundum deposits have been described 

 by Francis P. King.-"* All of the deposits occur in ultrabasic rocks 

 forming intrusive masses in the gneisses and schists. The veins 

 vary in form, and are from one to twelve feet in width. The fol- 

 lowing four types were recognized by King: (a) lime-soda feldspar 

 with quartz and phlogopite or vermiculite, (b) lime-soda feldspar 

 with actinolite; (c) a coarse-grained aggregate of lime-soda feldspar, 

 black hornblende, and margarite; (d) a massive vein made up of 

 light grass-green amphibole ("smaragdite"), hme-soda feldspar, 

 and a little chromite. All these types have walls of compact, scaly 

 chlorite, which quite frequently contains corundum. The second 

 type (b) is rare, and the corundum crystals usually possess a sheath- 

 ing of secondary margarite. The third type (c) is more common 

 than (b), but it differs from the first two in its massive, pegmatitic 

 character. The fourth type (d) is very rare, being known only at 

 the Bell Creek mine. Towns County, and in Clay County, North 

 Carolina. The I'ock is made up of a beautiful grass-green bladed 

 smaragdite, and feldspar, through which are scattered pink and 

 ruby-red corundum. 



At the Hog Ci'eek mine. Town 's County, a boulder of zoisite en- 



'^ Known to the old miners as the "fringe rock." 



^" Francis P. King, Geological Survey of Georgia, Bull., 2, 1894. 



