Work out ore reserve tonnage instantly with clear inputs, formula shown and shareable results.
In-situ tonnage is area times thickness times specific gravity. Mining recovery then removes ore left in pillars, lost to dilution boundaries or unmineable geometry — typically 8-15% in underground mining and under 5% in open pit. Only the recoverable figure belongs in a reserve statement.
Reserve tonnage
In-situ tonnage = area x thickness x specific gravity; recoverable = in-situ x mining recovery
Mineral resource and reserve estimates for public reporting must be prepared under a recognised code such as JORC, NI 43-101 or PERC by a competent or qualified person.
A resource is a geological estimate. A reserve is the part of a measured or indicated resource that is economically mineable after applying modifying factors including mining recovery, dilution, cost and price.
It converts volume to mass, and errors propagate directly into tonnage. It must be measured on representative samples, since it varies with mineralogy, porosity and moisture.