An “unprecedented” flow of cash into the high-risk mineral exploration sector has sparked a drilling boom that is causing huge backlogs at the laboratories whose assays determine success or failure.

More than $2.2 billion flowed into the 656 pre-revenue explorers on the ASX in the final three months of 2020, in a result that was 72 per cent higher than average and was described by advisory firm BDO as “unprecedented”.