Survey Track: Geology, Geophysics, Mapping and Core · Module 4 of 4 · about 15 min
Core, QA/QC and proving it
Drill core is the ground truth. Loggers record rock type, alteration, mineralization, structure and recovery for every run. Rock quality designation (RQD) measures how broken the core is by adding up the lengths of pieces 10 centimeters or longer as a percentage of the run.
Samples go to a lab for assay, and the results are only as good as the QA/QC around them. Crews insert blanks (material with no metal, to catch contamination), certified reference materials or standards (known grades, to check accuracy) and duplicates (to check precision). If the controls fail, the batch gets rerun.
Public companies report resources and reserves under strict rules: S-K 1300 in the U.S., NI 43-101 in Canada and the JORC Code in Australia. Each requires a qualified or competent person to stand behind the estimate. These rules exist because mining has a long history of fraud based on salted or faked samples.
The basic habits: chain of custody for samples, clean labeling, photos of every core box and data that can be traced back to the hole and depth.
Sources
Module quiz
5 questions, 4 correct to pass. You'll see what you missed and why, and you can retake it.