Watson — Association of Native Gold with Sillimanite. 241 



Art. XXII. — An Association of Native Gold with Silli- 

 manite ; by Thomas Leonard Watson. 



About a year ago Doctor Craig K. Arnold of Dahlonega, 

 Georgia, kindly sent me a very interesting specimen of pegma- 

 tite partly incased in mica schist, which contained in places 

 abundant large and small flakes of elementary gold readily 

 visible to the unaided eye. A thin section was cut from the 

 most favorable free gold-bearing portion of the rock for micro- 

 scopic study of the relations of the gold to the silicate minerals. 

 In view of the numerous published statements in recent years 

 on the occurrence of primary gold in igneous and metamorphic 

 rocks,* I consider the Georgia occurrence, regardless of min- 

 eral associations, to be of some interest as illustrating, micro- 

 scopically, the subsequent formation of the gold in the rock, 

 which from its observed relations by the naked eye might 

 readily be inferred to have formed contemporaneously with the 

 rock minerals. f 



A personal communication from Doctor Arnold informs me 

 that the locality from w T hich the specimen came is on Coosa 

 Creek, some four or five miles south of Blairsville, Union 

 County, Georgia. Although located in the Coosa Creek gold 

 belt, where gold mining has been engaged in from time to time 

 for many years, the several State Survey reports on gold contain 

 no geologic information on the area beyond the mere state- 

 ment that the rocks are schists or gneisses. There has been 

 some development work in the nature of inclines relative to 

 water level at the locality from which the specimen was taken, 

 but, so far as I am aware, practically nothing is known of the 

 field relations. 



The specimen is fresh and apparently represents mostly 

 vein matter, partly wrapped in a thin veneer of mica schist. 

 Quartz greatly predominates, but some feldspar is observed, 

 and this portion of the specimen has the appearance of a peg- 

 matite of irregular but moderately coarse crystallization of the 

 two minerals with some mica. The schist portion of the speci- 

 men is a mixture of large shreds and scales of biotite and mus- 

 covite through which are distributed somewhat numerous 

 rose-colored crystals of garnet. That portion of the specimen 

 showing much visible elementary gold from which the thin 

 section was cut, corresponds more nearly to the schist although 



*See Lincoln, F. C, Certain Natural Associations of Gold, Econ. Geol- 

 ogy, vol. vi, pp. 247-302, 1911. Lincoln cites references to the literature. 



f This statement refers to the enclosing rock and not to the pegmatite, for 

 it is believed the gold was probably introduced with the pegmatite and 

 therefore contemporaneous in crystallization with its chief minerals, quartz 

 and feldspar. 



