GABBROS OF EAST SOOKE AND ROCKY POINT. 
27 
copyrite. The average good ore, however, runs about 5 or 6 
per cent copper. Very few other minerals of any kind are found 
accompanying the chalcopyrite. A little quartz feldspar, calcite, 
-pyrite, magnetite, molybdenite, and zeolites have been observed, 
but the amount of these is so small as to be negligible; and 
restricted to the surface is a little native copper, oxidized copper 
minerals, and limonite. For practical purposes it may be said 
that the only gangue present is the hornblendite itself. 
As the large shear zones in which the ores are found yield 
more readily to erosional influences than the hard, unaltered 
gabbros, they are topographically expressed by the presence of 
small valleys on land ; and on the sea coast, where wave action is 
strong, as on the southwest coast, by narrow wave-eroded chasms. 
These chasms sometimes run in for 100 feet or more and thus 
form an infallible indicator of the presence of these zones. The 
valleys on land, however, have been filled in with soil, so that 
they are now only shallow depressions, difficult or impossible to 
trace in the present uncleared condition of the country. 
The shear zones in which the ores are found are strong 
and persistent, and can usually be followed for several hundred 
feet. The largest, that exposed on the Margaret, Copper King, 
and Eureka claims, is traceable for at least 4,500 feet. The 
strike, as described under “ Faulting/’ page 25, varies greatly 
between the different zones, but there are two principal sets 
of shear zones, one having strikes between north 10 degrees west 
and north 20 degrees east, the other between north 45 degrees 
east and north 65 degrees east. They vary in width from a few 
feet to one which is at least 250 feet wide. Their size and 
persistence render these deposits of considerable prospective 
value, and make it probable that they will continue to carry good 
values to considerable depths. There is, however, no reason to 
believe that they will increase in value with depth. They will 
more probably decrease gradually in value, probably with 
gradual increase of the proportion of pyrite. Native copper, 
which is frequently found in small amount at the surface, is 
due to surface alteration only, andcanriot be expected beyond 
depths of a few feet. 
