208 ECONOMIC GEOLOGY OF SILVERTON QUADRANGLE, [bull. 182. 
through and considerable drifting done on the low-grade North lode 
before the fact was suspected that the main lode had been overshot. 
These two veins show a very interesting relationship, which will be 
further described later on. This main adit connects, through stopes 
and raises, with the drifts of the "300 level," 140 feet below the "200 
level." A shaft has also been sunk for 300 feet below the 600 level 
(main adit level), and drifts run in both directions on the main lode 
at the 700 and 800 levels, while drifting was about to begin also on the 
900 level in 1900. 
Purington states that the "vein presents more the character of a 
solid filling between two walls than most of those seen in the district." 
To one coming to the study of this lode from the Silverton region, to 
the east and southeast, its striking feature is the regular and nar- 
rowly spaced zone of sheeting and the fact that the lode is composed 
of a series of more or less regular plates of quartz separated by sheets 
of country rock. In fact, this structure, combined with that charac- 
teristic of the linked-vein type, are the two most prominent structural 
features of the Tomboy lode. The peculiar intersections, at small 
angles, of various fissured zones referred to by Purington 1 appears to 
be a relatively subordinate feature, and was recognized by me at only 
one place. There is one curve in the main vein which is found on all 
the levels. At this curve on the 600 level a few small stringers were 
noted running out into the walls. However, in any but ideal expo- 
sures it is manifestly a most difficult matter to distinguish the inter- 
sections described by Purington from what I have preferred to regard 
as an example of linked-vein structure. 
The dip of the lode varies from 50° to 80° to the southwest — usually 
about 70°. It is commonly accompanied by a wet seam of clay gouge 
along the hanging wall. Along the foot wall. is a stringer, or vein, 
somewhat more solid than the auriferous portion of the lode, carry- 
ing galena and zinc blende and "frozen" to the wall. This foot- wall 
streak is sometimes in contact with the higher-grade gold-bearing 
quartz, sometimes separated hy a plate of country rock. Its solidity 
and fresh appearance is often in great contrast to the rusty auriferous 
ore alongside. It has been brecciated in places, and the ore solidly 
healed with white quartz. The foot wall alongside it has been rather 
irregularly fractured and veined. I was unable to ascertain whether 
this foot-wall streak was distinctly different in age from the aurifer- 
ous portion of the lode. 
The crushed and decomposed aspect of the gold-bearing part of the 
lode, often accompanied by black oxide of manganese, kaolinite, 
sericite, and copper stains, has been referred to by Purington. That 
these portions of it have been subjected to some movement subsequent 
to the original deposition of the quartz is shown b}^ the presence of 
clay seams traversing the ore. Subsequent fractures filled with wet 
Op. cit., p. 778, fig. 66. 
