HAILE GOLD MINE. 83 
about 12 to 1 on the average, and these concentrates are very clean, seldom containing over 
15 and often under 10 per cent of rock. The pyritic portion of the concentrates is practi- 
cally pure iron sulphide 1 , with only a slight amount of copper and occasional traces of arsenic. 
These concentrates range in value from only a few dollars up to $40 and more per ton. 
Between 90 and 95 per cent of their value is extracted by the Thies process of roasting and 
chlorination. It is probable that the total extraction is a little under 80 per cent of the assay 
value of the ore. 
A point to which the miners unanimously hold, but for which an adequate explanation 
has not yet been found, is the decided influence of joints on the value of the ore. This fea- 
ture seems to be best illustrated in the Haile ore body, but is said to apply also to the Bumalo 
and Beguelin deposits. There are three fairly well-defined systems of joints in the ore of 
the Haile pit. One system, approximately vertical and at a right angle to the strike, has 
little or no effect on the values except at the southwest end of the body, where the joints 
appear to be the boundary of the pay ore. Joints parallel to the foliation of the rocks like- 
wise have little influence on the values. Joints of the third* system, running from foot to 
hanging wall perpendicular to the dip and called "'floors," are said to have a decided effect 
on the values. For a few inches on each side of them, particularly on the underside, the ore 
is said to be better than elsewhere, and there is also said to be a difference in value between 
any two. These floors are well shown in PI. V. They have every appearance of being of 
later formation than the ore, and why they should so affect the value is not known, unless 
secondary enrichment has taken place along them, and that is probably not the case. 
ORE BODIES. 
The most remarkable feature of the Haile mine is its large ore bodies. Some idea of the 
size of these has already been given in the description of the developments. Roughly 
outlined on the surface by the presence of float gold the principal ore bodies were at once 
recognized. Subsequent work has resulted in the three large open cuts — the Haile, Bu- 
malo, and Beguelin pits. As the grade of ore which could be profitably treated progressed 
lower and lower, these workings have been extended into the outer portions of the deposits. 
All these principal ore bodies, which are lenticular in form, are influenced in their position 
by the structure of the rocks in which they occur. In other words, their longest horizon- 
tal dimension lies in a northeast-southwest direction, and they dip to the northwest. 
The Haile ore bod}MS an irregular lens of altered tuff whose foliation strikes about N.40° 
E., and dips on the average 55° NW. This foliated structure is preserved in the ore, as well 
as in the unaltered tuff, and is well shown in PI. V, which is a view toward the hanging wall 
of the new Haile pit near its bottom. If the field of the photograph extended a little farther 
to the right, the diabase dike shown in PI. IV could be seen. PI. V also shows incidentally 
the method of breaking the ore, which practically amounts to quarrying. The ore body 
following this rock structure is about 200 feet long from northeast to southwest, and on the 
average 100 feet thick at a right angle to the walls. From a description of the old Haile 
pit, now filled in and inaccessible, and from what can be seen underground, the northeast 
end of the deposit seems to narrow up, lens-like, till finally pay ore practically ceases. At 
the southwest, however, at least for the upper 200 feet, the boundary between pay ore and 
rock of too low grade to be worked is roughly a plane running approximately vertically 
across the deposit. There is in some cases even a joint or break at this place, on one side 
of which ore occurs and on the other practically worthless rock. This suggests the possi- 
bility of faulting along a plane parallel to the 27-foot .dike, but there is no other evidence 
of such an occurrence. It is difficult, however, to explain the sudden cutting off of the val- 
ues and of the alteration which produced them. 
About 100 feet below the surface, at the southwest end of the pit, a small bunch of quartz 
occurred holding some free gold. At 130 feet, about midway between the foot and hang- 
ing walls, at the same end of the pit, a horse of well-foliated sericite schist, soft in comparison 
with the surrounding silicified ore, juts into the pit, and continues with the general dip as 
far as work has gone. Just northwest of this, or toward the hanging wall, the ore is heavily 
