448 GEOLOGY AND GOLD DEPOSITS OF THE CRIPPLE CREEK DISTRICT. 
This remarkable ore body was mined down to a point above the present 900- 
foot level of the Portland mine, where the ore ceased. The old stope is at present 
accessible only on the 800-foot level. Here the ore body was roughly circular in 
plan and about 25 feet in diameter. The basalt dike has an average width on this 
level of 4 to 5 feet, but at the chimney expands to the east in an irregular swell and 
attains a local width of 15 to 20 feet. It is in this short swell and in the immediately 
adjacent breccia that the ore occurred. Just at this point the No. 1 Lee vein comes 
into the dike from the east, the ore body occurring at the junction of dike and lode. 
The less decomposed portions of the basalt, petrographically described on page 93, 
contain no ore, but much of the rock is traversed by numerous reticulated cracks 
along which decomposition and oxidation has proceeded, causing the rock to super¬ 
ficially resemble a breccia. This material is in part ore. The bulk of the ore on this 
level, however, seems to have occurred in the breccia alongside the dike at the junc¬ 
tion with the No. 1 Lee vein. This breccia contains abundant particles of microcline 
from the granite, is impregnated with pyrite, and is rather soft. It shows much oxida¬ 
tion, which penetrates the mass of the breccia very irregularly, with usually a sharp 
line between oxidized and unoxidized material. Nothing was seen on this level of 
the rounded pebbles referred to by Mr. Hills. The relation of the No. 1 Lee vein 
to the ore body on the 800-foot level strongly suggests that the vertical chimney- 
like character of the deposit may be due to the intersection of the basalt dike with 
the No. 1 Lee vein, but on the 500-foot level the lode known as the No. 1 Lee does 
not reach the dike at the Anna Lee chimney. It is probable, however, as Penrose 
suggests, a that better exposures would reveal on all levels the connection of the ore 
body with one or more fissures intersecting the dike. 
VALUE OF THE ORE. 
The average value of the Portland ore from 1894 to 1904 is shown in the table 
on page 171. It ranges from a maximum of $70.78 a ton in 1894 to $26.03 a ton in 
1902. Some of the best ore in the past came from the Diamond stopes in the granite. 
Large bodies of this ore near the 700-foot level were practically free from waste and 
averaged $100 to $150 a ton as shot down in the stopes. On the 900-foot level the 
tenor of the ore fell to about $25 a ton, and near the 1,000-foot level, where stoping 
was in progress at the time of visit, the ore shoot was barely paying $15 to $20 a ton. 
On the Hidden Treasure No. 3 stope, above the 1,000-foot level, about one- 
fourth of the rock broken is left in the stopes as waste. About 35 per cent of the 
material hoisted is screenings, with an average value of about $50 a ton. The 
remaining 65 per cent of coarse material is sorted to ore having an average tenor of 
about $20 a ton. 
While some very rich ore is sometimes found in the Captain stopes, these bodies 
are notable rather for their size than for unusual richness, and the ore as mined is 
probably not ver}^ different in tenor from the general average of the mine. 
a Sixteenth Ann. Rept. U. S. Geol. Survey, pt. 2, 1895, p. 207. 
