A Simple Chemical Method of Tracing Mineralization Through Light Non-residual Overburden

Synopsis The colour changes effected in a solution of dithizone by trace amounts of copper, lead, and zinc mineralization provide a sensitive field test for these metals. The method has been used with success by the United States Geological Survey to trace zinc orebodies under residual soils. The dithizone test is used here on samples of non-residual soil overlying a gold-bearing zone in which the gold is associated with disseminated sphalerite, galena, and chalco-pyrite. A gold-bearing zone was successfully traced under overburden ranging from a few inches to five feet in depth by means of this method. The method may prove useful in guiding preliminary trenching through light overburden, by outlining the extent of copper, lead, and zinc mineralization. Introduction The dithizone test affords a rapid, simple, and delicate test for the presence of zinc in soil and water and is suitable for use under field conditions. It has recently been used with success by the United States Geological Survey to outline a zinc-rich area in the residual soil over a primary zinc deposit in Tennessee. The purpose of the present study was to ascertain whether the method could be used to trace a gold-bearing zone, containing associated zinc mineralization, under shallow, non-residual, glacial overburden. The results obtained indicate that the method can be used to guide preliminary trenching in overburden up to six feet in depth. Tests made of the water near lake-shore outcrops also indicate that favourable prospecting zones may be located from the water, within five feet of the shore. It is felt that this simple field test should find a wider use in prospecting, because, under certain conditions, it can outline favourable zones and thereby reduce the amount of blind trenching necessary. The following pages describe the type of deposit tested, the method used, the .results obtained, and the difficulties encountered by a novice in the use of this chemical procedure. The author is indebted to the officials of Nor-Penn Mines, Limited, for their co-operation while the tests were being made; to the late Richard Bouska, Kenora prospector, for helpful suggestions; and to F. W. McCamus, University of Toronto undergraduate student, who ably assisted with the work.