The first economic study of a project, and the only one permitted to include inferred material.
An initial economic analysis of a mineral project that includes estimates of capital and operating costs, metal prices, and project economics. PEAs are less detailed than feasibility studies and carry higher uncertainty, but help determine if a project warrants further study.
A PEA is where a deposit first gets a dollar value attached, so it usually moves the share price more than any drill result. It is also the least rigorous study stage, and its permissiveness about inferred material is the reason.
Read the metal price assumption, the share of inferred material in the mine plan, and the capital cost. A PEA with 40% inferred feed and a $700M capex is a very different proposition from its headline NPV.
PEAs cannot be used to declare reserves, and their economics routinely deteriorate at pre-feasibility once inferred material is excluded and costs are firmed up.