IAnsome.] THE STOCKS OR MASSES. 103 
)iv now worked in quantity in the quadrangle is undoubtedly the 
iold ore of the Camp Bird. This is all milled, and averages from $40 
o 1200 per ton as delivered at the stamps. The gold ore of the Gold 
King mine is generally of low grade and can be worked to about as 
low a limit as any in the quadrangle. 
THE STOCKS OR MASSES. 
DEFINITION AND GENERAL DESCRIPTION. 
As denned by Von Cotta, 1 ore stocks are irregular bodies of ore 
possessing distinct boundaries. They differ from veins or lodes in 
the absence of a characteristic tabular form, and from impregnations 
in being fairly solid masses of ore with definite limits, or, in the case 
of stock works (Stockwerke), of a greal number of small veins or ore 
bodies constituting a mass which is worked as a whole. Phillips 2 
has translated Von Cotta's Stocke as "masses," but this word is so 
general in its scope and lias been used in so many classifications with 
varying significance thai ii is here discarded as a definite descriptive 
term. The nearly vertical ore bodies of the Red Mountain district, 
sometimes locally known as "chimneys." are substantially what Von 
Cotta has described and defined as standing (or upright) stocks. 
The stocks of the Silverton quadrangle are nearly vertical, irreg- 
ularly lenticular or spindle-shaped bodies of* almost solid ore, sur- 
rounded by an envelope of much altered, partly silicified country 
rock, which is usually impregnated with pyrite. Neighboring ore 
bodies are commonly connected by fissures, usually filled withwetclay 
gouge or kaolin. The sizes <>!' the individual ore bodies vary greatly. 
In plan, lengths of t0 or 50 feet and widths of 10 or L5 feet appear to 
have been not uncommon. Accurate sections of actual stocks are not 
now available, but individual ore bodies appear to h a ve been followed 
in many cases through several levels, and therefore to have had a 
nearly vertical maximum dimension of several hundred feet. Although 
sometimes nearly circular, the ore bodies generally showed a more or 
less elongated or elliptical plan, the longer axis of which usually lay 
more nearly north and south than east and west. The direction of the 
longer axis was not, however, always constant for all depths of a 
given stock. 
The ore bodies, particularly in the deeper workings, were usually 
found within nearly vertical zones of fractured, altered country rock, 
locally known as "ore breaks." Mr. T. E. Schwarz, who appears to 
have originated this term, says: 
The ore bodies of the Red Mountain district occur as chimneys or chutes, hav- 
ing great persistence in depth and varying greatly in dip and cross section, but 
ramifying toward the surface. The outcrops of these ore chutes occur along lines 
of alteration of the andesite or inclosing rock, and such lines were undoubtedly 
fracture planes of greater or less extent. These fracture planes or belts of meta- 
morphosed andesite were in the early days of the district termed by me "ore 
1 Erzlagerstiitten, p. 191, Freiberg, 1859. 2 Op. cit., p. 4. 
