16 On the Geological Distribution of Gold. 



constitute the characteristic of this rock. At the base of 

 the crystals and beneath the same in the exterior part of the 

 mass of the rock, gold is distributed; also among, but not 

 within, the crystals, though a few exceptions have been noted.* 

 Small seams of \ to § of an inch traverse the rock, contrary 

 to the cleavage (in N.W. by S.E.), filled with compact 

 quartz, stained with per-oxide of iron, some pyrites, and 

 yellow iron-ochre in abundance ; but here rarely any gold is 

 to be seen. The pulverized mineral produces diminutive 

 particles of gold by the process of washing, the most of which 

 have the appearance of fragmentary gold-leaf floating on 

 water. We often meet with finely divided gold, which 

 floats on water, but on nearer examination we find that 

 such particles, when from the veinstone, are of an an- 

 gular form. In this locality it is as it were small por- 

 tions of gilders 5 gold, the least breath moving the same, 

 just like particles of a feather. Certainly, this kind of 

 gold is among singular exceptions, and of great interest 

 respecting the modus operandi by which it has been disse- 

 minated. Thus the rock in which it appears may be viewed 

 among gold-bearing curiosities. The said rock was discovered 

 in the province of Cauca, of N. Granada, in 1850. 



It is said that sandstone of the Lias group, containing gold 

 disseminated in small particles, has been found in Hungary. 

 This rock, as observed in the northern districts of S. America, 

 has not proved auriferous. 



In the Brazils, the following auriferous rocks were found 

 many years ago : 



A Conglomerate, consisting of angular fragments of specu- 

 lar and magnetic iron-ore, occasionally containing fragments 

 of flexible sandstone (itacolumite) of a pale-red hue, some- 

 times having fragments of chlorite and talc-schists, these frag- 

 ments embedded in a cement of a ferro- argillaceous com- 

 position, forming a compact rock, occupying the top as well 

 as the slope of the hills and also the valleys, resting on mi- 

 caceous and clay-slates and on a schist of specular iron-ore. 



* In California, I was gratified in seeing a rare specimen of a group of 

 auriferous quartz-crystals (the largest of which was about 2 inches in height, 

 and presented facets of nearly f of an inch) occupying a piece of micaceous 

 clay slate, in size aboiit 7 inches by 4. This group was surrounded with 

 small closely studded crystals which covered the fragment. Gold, in a 

 varied angular shape, was abundantly spread among the smaller, and par- 

 ticularly at the base of the larger crystals. Three or four of the latter 

 enclosed several gold particles, which were seen in the centre of the lower 

 portion of the same. 



