GEOLOGY OF THE BEAK LODGE D1STEICT. 287 



different .specimens were collected in a radius of as many yards. The 

 prevailing rock was a very coarsely-crystalline feldspar-porphyry, with a 

 fine porcelain-like matrix, breaking* with a sharp conchoidal fracture. The 

 feldspar crystals were often very perfect, and from an inch to two inches 

 long. Flat and thin crystals were common, often joined together, with the 

 shorter axis of one reversed, as " twins." The specimens varied in color 

 from light yellow or yellow-brown to gray, and large masses of rock in 

 the middle of the " ledge" were made up of feldspar intermixed with 

 irregular masses of limonite iron ore and black oxide of manganese. 

 Bowlders of iron and manganese which would weigh several hundred 

 pounds were scattered over the surface of the ground. The mineral was 

 solid, compact, and exceedingly heavy, but the two oxides were distinct in 

 the mass, though often closely intermixed. Manganese and limonite 

 occurred, filling the spaces between the large feldspar crystals and impreg- 

 nating the rocks irregularl}' throughout until it resembled a " breccia." 

 Evidences of an octoheclral or cubical crystallization in the limonite indi- 

 cated that it was derived from the decomposition of iron pyrites, and traces 

 of the latter mineral were found on breaking the rock. 



No gold could be detected in this formation by the eye; but, suspect- 

 ing its presence, the different specimens collected were carefully sampled 

 and submitted to Mr, P. de P. Ricketts for assay. The result showed the 

 presence of a decided trace of gold, probably contained in the iron and 

 manganese oxides. 



Prospecting in the dry ravine a 'short distance below this ledge, the 

 gravel from off bed-rock was found to be largely composed of material 

 derived from the disintegration of the ledge. Twelve fine colors of gold, 

 or about half a cent to the pan, was obtained as an average of several 

 tests, and each time nearly a pint of gravel and pebbles of manganese and 

 limonite was left in the pan after washing out the lighter clay and feldspar. 

 It would seem probable that the whole of the gold contained in the gravel 

 in this ravine had been derived from the decomposition and denudation of 

 the above ledge. 



The occurrence of gold in trachyte without any quartz being asso- 

 ciated with it has been previously reported from several mining districts in 



