The appended sketch will give an idea of the present development of the Helvetia, which is one of the most promising properties in the district, and a type of the best class of mines of its kind found there.
The Helvetia, like other mines of the district, occurs in the crystalline schists, the quartz being found as lenses inclosed in the country rock. Some of the lenses might be mistaken for fissures, but I failed to see one possessing the characteristics of a “fissure.”
Nearly all the lenses exhibit a tendency to “make” into the hanging wall side of the country rock, the lenses of quartz following each other in a general direction, but at an angle with the stratification of the schists, and are separate and distinct from each other, being separated at the ends (where they sometimes overlap) by the “leaves,” as they may be termed, of the schistose country rock. These lenses were doubtless caused by a compressive stress on the schists, which had a tendency to split them, but was not powerful enough to cause an abrupt fracture. The accompanying sketch may convey an idea of the occurrence of these quartz lenses.
WORKINGS OF THE HELVETIA MINE NEAR JULIAN
LENTICULAR QUARTZ BODIES IN SCHISTOSE ROCK
By the above sketch it will be observed that there is a tendency on the part of the quartz lenses to follow a given direction, which lies at a small angle across the strike of the schists, and that these lenses are not connected, but occur independently, though all are the result of the same force which flexed and split the strata.
Other mines about Julian were idle at the time of my visit, the most of them being inaccessible, owing to water in the workings. Considerable money has been expended on the Owens Mine in an attempt to drain and recover the workings, but it was abandoned after several months of work and considerable expense.
More activity was exhibited in the mines about Banner than any other part of the district.