Gold in Placers.— Wood. 378 
In Montana, of which country this paper more particularly 
treats, gold occurs in situ. 
1. Native in quartz veins in granite, slate, and quartzite. 
2. In chemical combination with iron pyrites, also copper 
pyrites. These veins occur in slates and granites, the accompany- 
ing gangstone usually being quartz. 
3. In brown iron ores the result of weathering and chemical 
decomposition of iron pyrites, which weathering or oxidizing in- 
fluence may extend to considerable depth in the vein owing to the 
action of percolating surface waters, or be limited to a few feet. 
The gold in this instance is free, but in a very fine flour-like 
condition. Such veins where the ordinary action has extended to 
a great depth, usually occur in slates or a rock which admits of 
the ready percolation of water. This changed condition is seen 
in all veins holding iron and copper sulphides. 
+. Gold occurs in more or less quantity in all veins in Mon- 
tana. In pure galena a small trace is obtained, as well as in 
copper sulphide. 
d. In a very few instances a small percentage of gold has 
been found in quartzite dikes. The quantity is rarely sufficient to 
warrant working. 
As to its physical properties the gold may be a light yellow or 
a dark yellow, holding a variable proportion of silver. It may 
occur, 
ae 
In large nuggets. 
Moderately coatse—angular. 
. - Moderately coarse—much worn. 
4. In grains and scales (fine). 
5. Flour-like condition. 
vo 
3 
Some of these nuggets have been of considerable size, one ob- 
tained at St. Louis gulch, weighing nearly 21 ounces, while those 
weighing two or three ounces and more are of frequent occurrence. 
NovreEs 
1. A probable explanation will be found farther on. 
2. When angular, the gold has not been subjected to much 
attrition and not carried far from its source. 
3. Carried considerable distance and subject to much attrition. 
+, A very common form for gold to assume in placer beds, 
This is its most common condition in the vein material, thin 
leaves and scales. 
