I think your .04 oz per cubic yd is quite reasonable going by the statements on the company website: In 1983, approximately 9,000 cubic yards of material was processed from Tub Springs Gulch with an average grade of 0.03 ounces per cubic yard. In 1993, several 50 cubic yard bulk samples were tested from the Lower Black Rock Canyon area with an average grade of 0.045 ounces per cubic yard. http://www.pacificgoldcorp.com/properties/nevadarae/production-history.html