32 Sypney H. BALL: 
and about 110m (360 feet) of shafts and drifts in the adjacent cupriferous 
schists. The total production has been some 90 tons of copper. 
The country rock is granite, containing many inclusions of basic 
igneous rocks, mashed to chlorite schists, frequently porphyritic. There 
is associated gray, fine-grained, biotite-quartz-orthoclase schist, which 
was originally, presumably, either a monzonite-porphyry or a latite. 
Intrusive in both the schists and granite is a dike of schistose chloritized 
diorite-porphyry and numerous thin dikes of later diabase. 
The Josva vein strikes from N. 36° E. to S. 36° W. and dips S.E. 
65° parallel to the enclosing schists. It is exposed for only 64m (210 
feet) and passes under the sea at either end. One kilometer to the south- 
west across a bay is the Lillian mine, presumably situated on the same 
fracture. | 
The hanging wall is chlorite schist and the foot-wall, biotite-quartz- 
orthoclase schist. The two walls, from 1 to 11/, m (31/, to 5 feet) apart, 
are well defined fractures, there being beneath the hanging wall from 
2.5—7.5 cm (1 to 3 inches) of gouge. The rock between the walls is 
more schistose than that beyond them and hence the vein weathers 
as a depression. 
The ore occurs as isolated or linked lenses in a mineralized band 
from 0 to 0.7 m thick (0—2.3 feet) immediately beneath the hanging 
wall. At the surface this mineralized band averaged 32 cm (13 inches) 
thick, but decreased to 11 em (4.5 inches) at the bottom of the shaft, 
where values stopped. In the schist are numerous small intrusions of 
granite and the amount of ore increases in these brittle rocks. In ad- 
dition to ore filling fractures in granite some ore replaces its felspar. 
A partial analysis of good ore follows: copper 5.14 %, silica 51.6 %, 
sulphur 1.7 %, iron 1.98 %, alumina 13.45 %, lime 8.75 %. The рге- 
cious metal content varies directly with that of the copper, there being 
present for each unit of copper 0.003 oz., gold and 0.4 oz. silver. 
Bornite is the predominant ore mineral: chalcopyrite and chalcocite 
are less abundant, and malachite and chrysocolla are unimportant. 
Native gold is reported in fractures near the surface. The gangues in 
the order of abundance are epidote, fluorspar (usually purply, rarely 
green). quartz, calcite, actinolite, brown garnet and prehnite. Epidote, 
garnet, quartz, actinolite, and some calcite, chalcopyrite, and bornite, 
crystallized first, although the garnet is older than some of the bornite: 
next prehnite formed: after it fluorspar, and lastly a second generation 
of calcite. Molybdenite and specular hematite, although they were not 
observed in association with the ore, have been found nearby, and are 
presumably contemporaneous with the first group of minerals. The 
only secondary gangue mineral is the zeolite, stilbite, which in places 
occurs on malachite. 
