Insertion rates
"5%" and "20%" are both correct — 5% is per control type, 20% is the total. Simón's survey of seven QA/QC consultants all lands near 20% (range 15–25%), and "a 20% control-sample insertion rate has practically become an industry standard."
His recommended breakdown for core drilling:
| Type | Rate |
|---|---|
| Duplicates (twin 2% + coarse 2% + pulp 2%) | 6% |
| Standards (CRMs) | 6% |
| Blanks (coarse 2% + pulp 2%) | 4% |
| Check samples (umpire lab) | 4% |
The 1999 TSE-OSC regulatory floor: 1 duplicate + 1 blank + 1 standard per 20 samples = 15%. Practical refinement (Bloom): match blank spacing to the lab's rack size — one per 25–40 samples tracks a fire-assay rack.
The finding that actually bites
Achieved ≠ planned, routinely. Rainy River planned 3.3–5% CRMs and achieved 2.2% on average; blanks landed at 0.7–1.4%; prior operators submitted none at all. The rate that matters is the one computed from the data — per period, per hole — never the one in the protocol document. And rigid rates aren't sacred: tailor proportions to the problems your program actually has.
In geoDB
Your planned rates live in the project's QC insertion protocols; geoDB computes actual QC presence per certificate and reports low insertion in its batch QC summary (flagging under ~3–5%). The approval page states the achieved rate and any missing QC type right above the approval decision, and stores what it said with the approval — but it is guidance, not a block: you may approve any certificate you want to, including one with no QC on it at all. Keep the achieved-vs-planned comparison in your own review habit.