GRANITES OF NORTH CAROLINA 393 



being observed in any one of the sections. Some microperthite occurs. 

 Biotite of deep brown color and strong pleochroism is uniformly 

 distributed in large amount through the sections, altered principally 

 to chlorite, a colorless mica, and occasional epidote. Areas of micro- 

 graphic structure are abundantly distributed through some of the 

 sections, clearly indicating the overlapping of the periods of forma- 

 tion of the quartz and feldspar. Pleochroic titanite in crystals and 

 grains is quite freely developed in one of the sections. Inclusions 

 of apatite and zircon are fairly constant. 



The Mecklenburg county areas. — Biotite-bearing hornblende gran- 

 ite occurs one mile east of Davidson in the extreme northern part of 

 the county, and again five to six miles south of Charlotte in the extreme 

 southern part of the county. Hand specimens of these granites are 

 entirely different from, and bear no resemblance whatever to, those 

 of the types previously described. They are of medium texture and 

 gray color, and in the locality south of Charlotte a few bowdders have 

 been worked off for monuments. Much plagioclase is present in 

 association with the potash feldspar. Compact hornblende with 

 strong cleavage development is the principal ferromagnesian mineral 

 present. It is accompanied by more or less biotite of the usual kind, 

 which varies greatly in amount. 



The granite to the east of Davidson contains large lath-shaped 

 crystals of the hornblende distributed through it, which measure in 

 extreme cases as much as one and a half inches in length. All grada- 

 tions in the size of the hornblende individuals down to the smallest 

 grains occur. Chlorite is one of the chief alteration products of the 

 ferromagnesian constituent. Much titaniferous magnetite occurs 

 along ^^ith some of the usual minor accessories. 



THE WESTERN PIEDMONT GNEISS AND GRANITE BELT. 

 GENERAL CHARACTERS. 



The principal rocks of this belt are gneisses of variable mineral 

 composition. A residual of biotite granite-gneiss, closely resembling 

 in the hand specimens and in mineral composition the well-known 

 Lithonia area of granite-gneiss in Georgia,^ occurs in Alexander 



I "Granites and Gneisses of Georgia," Bulletin No. Q-A, Geological Survey of 

 Georgia, 1902, pp. 125 ff. 



