310 G. P. Merrill — Free Gold in Granite. 



the mass of the quartz granules and feldspars. In such cases 

 it does not appear to have been deposited, as was at first thought 

 probable, along fissures, as a secondary constituent, but is com- 

 pletely enclosed in the fresh and ud fractured minerals in most 

 beautifully perfect arborescent and extremely thin, platy forms 

 as if deposited directly from solution. Careful search was made 

 for indications of impregnation, by means of solutions, along 

 preexisting fractures or cleavage planes. But, while in some 

 cases the metal does occur in thin platy forms in what are now 

 fractures or minute rifts, there is nothing to indicate that these 

 existed as such at the time the gold was deposited, but rather 

 that they are due to the subsequent weathering of the rock. 

 The plates do not lie in one common plane, but are scattered 

 at haphazard at all angles with the orientation of the crystals 

 in which they are imbedded. Moreover many of the forms 

 are so branched, moss-like or arborescent, that it is impossible 

 to consider them as formed in this manner. No pyrite or 

 other sulphides or their decomposition products can be detected. 

 There is apparently no way of accounting for the gold other 

 than by considering it an original constituent of the rock, a 

 product of cooling and crystallization from the original magma. 

 This of course on the supposition that the rock is a true gran- 

 ite, which it in every way resembles. 



This occurrence is of unusual interest, if not of importance. 

 So far as the writer is aware, nothing quite comparable with it 

 has been noted. 



J. B. Jaquet has briefly described and figured * an occur- 

 rence of free gold in microcline, the rock in which the latter 

 occurs consisting essentially of microcline and quartz, impreg- 

 nated with hematite. He remarks that it somewhat resembles 

 the coarsely crystalline granite found in the schists of the 

 region. Adams and Dawson have described f the ore of the 

 Treadwell mine, Alaska, as a hornblende granite, " much 

 crushed, altered, and impregnated with secondary quartz, 

 calcite and pyrite," the last named carrying the gold, a consid- 

 erable portion of which is free. In the present instance, how- 

 ever, the granite is altered only by the ordinary processes of 

 superficial weathering, and as above noted contains no pyrite 

 or other sulphides. The occurrence of the gold completely 

 imbedded in the clear glassy quartz and unfissured feldspars 

 apparently precludes the possibility of a secondary origin. 

 The beautiful, highly lustrous yellow metal stands out in the 

 sections, clear and distinct, whether in quartz or feldspar, 



* Geol. of the Broken Hill Lode, etc., Mem. Geological Survey of N. S. Wales, 

 Australia, No. 5, 1894. 



f Am. Geologist, Aug. ] 889. 



