Regarding your Nov. 6 editorial, “Is Pretium petering out?”, the Valley of the Kings bulk sample program at the Brucejack project in B.C. was designed to incorporate both a sampling program with the sample tower, and the results from processing of the 10,000 tonnes of excavated material to produce gold.
It was never a question of which method was “cheaper” to get a representative sample (and the tower operation was not cheap), but rather how we might get as much information out of the program as possible, given the 10,000-tonne limit for a bulk sample. (We also incorporated a 16,789-metre drilling component.)
The plan was to compile all the generated data, validate the results, and then compare the result back to the block model for our mineral resource estimate. Strathcona Mineral Resources was the independent qualified person (QP) with responsibility for the excavation and sampling operation, and Snowden is the independent QP with responsibility for the modeling, and review and sign-off of the milling and processing.
We have concerns as to whether the sample tower really yielded representative results, and have been advised that a sample tower program simply may not work for a heterogeneous, high-nugget coarse gold deposit like our Valley of the Kings.
As we reported in our Oct. 22, 2013 news release, the results from processing the first cross-cut (426585E) demonstrated that 94% more gold was produced from actual processing than was estimated by results from Strathcona’s sample tower for the same material. We don’t believe that this variation of 94% is an acceptable result.
The bigger point is that the bulk sample program is a scientific undertaking, and Pretium adheres to a very fundamental scientific principle: you first have to compile all the data and ensure you are measuring what you are supposed to before you can make any meaningful conclusions.
In respect of an “industry rule of thumb” of capping assays at 30 grams per tonne gold to diminish the nugget effect — how many gold projects are there in the world today that host 139 intersections grading over a kilogram per tonne gold, 398 intersections grading between 100 and 1,000 grams per tonne gold, and 851 intersections grading between 15 and 100 grams per tonne gold?
We’ve encountered extreme grade gold consistently, with a hit rate of one plus-kilo gold intersection for every 534 metres of drilling this year. The high-grade gold mineralization is hosted in a well-defined stockwork system which lends itself very well to bulk mining.
We don’t see this as an “overemphasis on high-grade” – just the hallmarks of an exceptional high-grade gold project.
Michelle Romero, vice-president of corporate relations Pretium Resources Vancouver
Let’s sock it 2um!!! Those new york white shoe boyz