NOME REGION. 131 
joint planes, and as narrow veins of fairly regular thickness but small 
longitudinal extent — that is, much flattened lenses. A broken sur- 
face of such a vein may show sulphides, generally pyrite, or more com- 
monly a cavernous interior filled with iron oxide derived from the 
alteration of pyrite. Some of these veins are known from numerous 
assays to carry gold in small quantity. 
Calcite veins are almost restricted to the limestone areas, or at least 
to these areas and their immediate vicinity. They reach thicknesses 
of several feet at various exposures, but like the quartz veins have not 
been found to continue horizontally for any considerable distance. 
It should be stated, however, that the lack of outcrops, due to the cov- 
ering of loose weathered material or of moss, is a serious obstacle con- 
fronting the prospector who attempts to trace veins in this region, and 
makes it quite impossible without much labor and expense to deter- 
mine their extent on the surface. 
Numerous calcite veins are exposed in the limestone area of Anvil 
Mountain and its continuation east of Dry Creek. Prospect holes 
have been sunk on some of them and many have been staked as mining 
property. Free gold is found in small amount in some of these veins. 
Besides the veins of quartz and calcite described above there are 
also veins made up of quartz, chlorite, and albite. These were 
observed most frequently in the Anvil-Newton Peak area. 
No well-defined belt of mineralization has yet been established. 
There are restricted areas, nevertheless, where such secondary deposits 
are more highly developed than in the remaining parts of the region. 
The most important of these includes the upper portion of Anvil and 
Dexter creeks, the lower part of Glacier Creek, and a portion of Snake 
River extending north from Glacier Creek. Excavations on the 
third-beach line have shown that there also much of the schist bed 
rock is filled with small mineralized quartz veins. In this connection 
it may be stated that north of Rock Creek and on Pioneer Gulch gold 
is found in the surface debris, where concentration is due to decompo- 
sition of the bed rock and removal of the lighter material, the heavier 
constituents of the rock being left almost in place, since their move- 
ment is chiefly downward rather than in a lateral direction. In both 
places the bed rock is known to contain small mineralized quartz veins, 
and north of Rock Creek they carry sufficient gold to lead to some 
attempt at development. No unquestionably igneous rock bodies are 
known in this disturbed area. The greenstones either do not occur in 
any considerable amount or their identity is lost through alteration. 
One small exposure of greatly altered siliceous rock north of Specimen 
Gulch was at first considered to be an acidic granite, but there is much 
doubt concerning it. 
Brooks (p. 25) emphasizes the fact that many of the most important 
placer deposits of the peninsula are found in localities where both 
