26 GBAVEL AND PLACER MINING IN ALASKA. [bull. 263. 
Occasionally, however, the precious mineral sought lies in a matrix 
of fine sand, or even entirely in the crevices of the bed rock on which 
the alluvial deposit rests. Obviously the term gravel mining does 
not cover the cases in which detrital gold is extracted from such 
matrices, and the general term placer mining has been, therefore, 
added in the title of this report for want of a name which shall 
include all operations considered. 6 When in the subsequent matter 
the terms gravel deposit, gravel washing, and gravel mining are 
employed they must be understood, for the sake of brevit} T , to include 
the consideration of all classes of deposits in which gold of detrital 
origin is found. 
The term " elluviaV has been applied to placer deposits formed by 
the rotting of rock in place to greater or less depth. 6 ' Such deposits 
do not occur in the portions of Alaska visited, and may be excluded 
from consideration. 
In regard to the valuable contents of the deposits, it should be 
stated that in all the cases here considered gold is the mineral sought. 
Platinum or any minerals of the platinum group have not been found 
in paying quantity in any part of Alaska. Alluvial tin has been 
found and mined in the western portion of Seward Peninsula. The 
deposits were not, however, visited by the present expedition/ 7 
a Placer, according to a Spanish definition, is a place near the bank of a. river where gold dust is 
found. Lindley on Mines, sec. 419, makes the following comments: 
"Dr. R. W. Raymond (Glossary of mining and metallurgical terms, Trans. A. I. M. E., vol. 9, p. J 
164) defines the word placer as a deposit of valuable mineral found in particles in alluvium or dilu- 
vium, or beds of streams. He adds to the definition the statement that, by the United States 
Statutes, all deposits not classed as veins or rock in place are considered placers. As was said by the 
Supreme Court of the United States (Reynolds v. Iron S. M. Co., 116 U. S., 687-695; 6 Sup. Ct. Rep., 
601), in distinguishing the two classes of deposits: 'Placer mines, though said by the statutes tol 
include all other deposits of mineral matter, are those in which this mineral is generally found in 
the softer material which cover the earth's surface, and not among the rocks beneath.' " 
It is evident that the term placer mining as used in the present report covers a much more limited 
field than would be the case were the term placer used in its broad legal sense. 
b The term alluvial mining, used in Australia, is not generally employed in the United States. 
cEng. and Min. Jour., vol. 77, May 5, 1904, p. 722. 
dSee the report of A. J. Collier (Bull. U. S. Geol. Survey No. 229, 1904) for an exhaustive account of 
the York tin deposits. 
