In the preceding pages some unit costs of sinking, drifting, cross-cutting, and drilling have been presented, together with a few costs covering entire churn-drilling campaigns. Few figures are available covering the total cost of exploring a property before reaching a decision to develop it for production. However, figures are available covering expenditures for exploration and development at a few properties during various stages of exploitation before the productive stage, and the following data are summarized from those figures.
The following conclusion with respect to exploration costs in northern Canada gold districts is taken from Information Circular 6693:
Although conditions differ at individual properties so that no estimate can be made of the expenditure required to prove a given prospect, the figures do indicate that in embarking upon the development of a prospect in this region, one should be prepared to expend at least $250,000 to $300,000 in order to determine whether the property will justify additional expenditure for a mill. It may require the expenditure of only a fraction of this amount in some instances to reach the conclusion that the property will not make a producer. On the other hand, this amount or much more may be required to prove that there is or is not a mine.
1. Central Patricia mine.—This property consisted of 18 claims in northern Ontario, 120 miles from the railroad by winter tractor route. At the end of the exploration campaign, 33,155 tons of ore had been proved, together with an estimated additional “possible” 12,000 tons. A vertical, three-compartment shaft had been sunk to a depth of 527 feet, four shaft stations cut, and 1,776 feet of drifting and 1,019 of crosscutting completed. Preliminary work included 6,000 feet of diamond drilling, 1,050 linear feet of surface trenching, hauling of equipment and supplies, and construction of camp and temporary mine buildings. Although much of this work was of service later in development for production, the cost may reasonably all be charged to exploration. The summarized costs follow:
In addition, $60,325 had been expended covering inventory at time of temporary shut-down, and not charged off on the books.
2. Ashley mine.—This property was 42 miles by winter road from Elk Lake, Ontario, the end of the railroad. It embraced 23 claims covering 951.7 acres. Discovery was made in October 1930, and the following figures cover expenditures during various stages for exploration and development up to the time a mill was completed and ready for operation (August 31, 1932) but excluding the cost of the mill:
3. Bobjo.—This property is in the Patricia district, northern Ontario, 120 miles from the railroad. In 1928 and 1929 it was partly explored by a two-compartment, vertical shaft (6½ by 12 feet) to a depth of 268 feet. Two shaft stations were cut and 1,786 feet of lateral development was completed. The summarized cost of this work was as follows:
4. San Antonio.—This property is in Manitoba remote from rail-road transportation. Following are the summarized costs of exploration:
1. Golden Belt—This property is in Yavapai County, Arizona, 15 miles from the railroad. Following is a summary of the exploration costs, including camp buildings, roads, mine equipment and supplies, 750 feet of open-cuts, approximately 598 feet of tunnels and drifts, 95 feet of raises, and 825 feet of 14° incline, and cost of stoping 2,370 tons of ore taken out during the period covered: