MINES OF RAVEN AND GUYOT HILLS. 
319 
external silicification of the unknown mineral, with subsequent solution and removal 
of the unsilicified core. Finally pyrite was deposited in small sharp crystals upon 
the surfaces of the quartz crystals. Other specimens show that the fissure walls 
were in part coated with crystals of dolomite upon which are implanted tetrahedral 
crystals of tetrahedrite associated with a little pyrite. This second type of ore is by 
some considered characteristic of the Jackpot lode. 
Some of the tetrahedrite ore being stoped by lessees on level 15, near the 
Doctor shaft, contained from 6 to 27 ounces of silver per ton, while some ore previ¬ 
ously extracted was said to contain up to 200 ounces of silver and 20 ounces of gold. 
At this point in the mine a seam of coal (see also p. 31) lies along the foot wall of the 
tetrahedrite ore and is stoped with the latter. The coal is reported to have given 
an assay value of $40 per ton in gold, but it is doubtful whether the sample was 
taken with sufficient care to avoid including some of the adjacent ore. 
The ore now mined by lessees from the Smith-Reilly lode and associated 
fissures is of the usual type—calaverite associated chiefly with quartz and fluorite 
in narrow cracks in the breccia. 
PAY SHOOTS AND LODE STRUCTURE. 
The Doctor-Jackpot lode is a remarkably w r ell-defined and regular zone of 
parallel Assuring. It has been followed on the 550-foot Morning Glory level for 
2,900 feet, and is without doubt one of the most distinct and persistent sheeted 
zones in the district. In its typical development, as seen on the 700-foot level 
northeast of the Morning Glory shaft, the lode consists of two regular and well- 
defined parallel fissures from 3 to 6 feet apart. These fissures, particularly the 
foot-wall fissure, exhibit more evidence of movement of the w r alls than do most of 
the Cripple Creek lodes, and some slickensided surfaces w r ere observed, but not such 
as to indicate any great displacement. Between the tw o main fissures the breccia is 
usually sheeted, or divided into thin slabs of an average thickness of 2 or 3 inches 
by minor parallel fissures, and close examination often reveals less conspicuous 
cracks dividing these slabs into still thinner plates. The fissures of this sheeted zone 
are not all filled with the same material. Some are occupied by veinlets composed 
chiefly of a fine-grained purple aggregate of quartz and fluorite, locally inclosing 
calaverite. Others contain dolomite and quartz with tetrahedrite and a little 
fluorite, and still others are filled with rather crumbling aggregates of pyrite. In 
some cases the veinlet forms a fairly solid filling, but in others it is more or less open 
and vuggy. The lode varies from point to point in w T idth and in the number and 
disposition of its constituent fissures. In some places there is little more than a 
single w^ell-defined fissure. In others the fissures diverge so as to inclose horses of 
country rock as much as 30 feet in width. Such a horse appears in the northeastern 
part of the 700-foot level, where the stronger hanging-wall zone is sometimes called 
the Doctor lode, wdfile the foot-wall zone is called the Jackpot lode, and contains 
tetrahedrite. Somewhere below the 550-foot Morning Glory or Doctor level 14 these 
two zones of Assuring appear to join and form a single well-defined lode. Near the 
Doctor level 10, however, in the vicinity of the Doctor shaft, the lode again shows 
two sheeted zones separated by a horse of breccia with a maximum width of about 
