DESCRIPTION OF THE IRON ORES. 
69 
faulting of the ore deposits is provisionally assigned to the postlava 
period, because this has been a period of considerable faulting 
throughout the district. 
500 feet 
Fig. 7.— Cross section of Blowout contact deposit, a, Iron ore; b, laecolitlric andesite; c, Homestake 
limestone; d, altered Homestake limestone. 
The shape of the deposits in vertical cross section is incompletely 
known because exploration has been shallow. Available informa- 
Pinto sandstone 
Andesite 
Homestake limestone 
1/4 
Vz 
Claron limestone 
3 /4 lmile 
Vertical scale twice horizontal 
Fig. 8.— Cross section southeastward through Lindsay Hill, showing structural relations of ores. 
tion is summarized in figs. 4, 5, 6, 7, 8, and 9. Inferences drawn 
from the manner of development of the ore are discussed on pages 76 
and 85. 
Ore 
Prese,, 
Ore 
*<"/a 
Ore 
\/\ 
ws$. 
Y/*- -•- + -»■-<-+++ + + + + t i +-*-++ ++ + + -r- + 1 
Yr t +--H--l--l--H- + + + ++-l--r+4++ + -r--r-+-i-F 
/- + + + -r + + + -t+ + + ++-r-+ ++4+ ++ + +t-rf 
<$/y#+ + + -H-+ + + + + -t- Andesite+ + + + + + + ++-»- L 
jJ^Ca-*- +-r-+ + + + ++ + + -r-t--|-+i- + -r+ + -r+ + -r+-r| 
3 tC#' + + + + -+ + + + + +-t+- ( -++ + + -t-+ t++ + ++ + +' 
ffTO^I 
-t-4 
Base unknown 
2 miles 
Fig. 9.— Ideal cross section through Iron Mountain laccolith, showing structural relations of ore: 
ORE DEPOSITS IN BRECCIAS. 
The ore constitutes cements or minute veins in fault breccias 
formed by the Homestake limestone, Pinto quartzite, or andesite ai 
several localities, as follows: Limestone and quartzite at the Milner 
mine, Dear, Excelsior, Duliilh No. 2, Desert Mound: andesite at the 
