Technical Report for the Fort Knox Mine - Kinross Gold

Fort Knox Mine Technical Report17.2.2 Survey DataPre-mine topography is based on airborne photogrammetric elevation data contoured at1.52 meter (5 foot) intervals. The coordinate system at the mine is a local grid modifiedfrom State Plane coordinates. Mining progress is constantly updated by survey traversesof bench toes using a backpack GPS (global positioning system) system and periodicallyupdated using airborne photogrammetric methods. The airborne topography wascompleted in August 1998 by AeroMap U.S, of Anchorage, Alaska, and updated in April2003, 2005 and May of 2007.17.2.3 Assay Grade CappingOriginal gold assays are capped at 0.50 oz Au/short ton (17.14 g/tonne), which displaysa shift in the lognormal distribution of the database. Two hundred eighty-three intervalswere capped at 0.50 ounce per ton, representing 1.06% of all assay data above the0.0125 ounce gold per short ton (.43 g/tonne) cutoff grade. These data are cappeddirectly in the MineSight database file knx011.07d.Figures 17-1 and 17-2 display the univariate statistics of the uncapped and cappedassay data respectively for the Fort Knox deposit, excluding rejected data.17.2.4 Drill hole CompositingGrade-capped assay intervals were combined into 30-foot bench composites stored atthe mid-point as “AU1” items in the knx009.07d composite file. Rejected assay intervalswere excluded from the compositing.Figure 17-3 presents the 2006 histogram frequency plot and statistics for the benchcomposite data for the Fort Knox deposit.Composites were assigned a code corresponding to one of the four defined lithologicdomains (see section 16.2.6). A composite was given the code corresponding to adomain if more than half of its length fell within that domain.54