Generating a Resource Estimate by Magnetic Field Inversion ? a Study of the Hawsons Magnetite Deposit, NSW

Abstract

Resource definitions have regulatory requirements of sampling from drilling. Drilling provides direct and precise measurement of ore grades and characteristics which determine the financial viability of the resource, but close drilling of a resource is very expensive. Magnetic field inversion is an indirect method of estimating ore grades and volumes. It is generally only assigned an exploration role to make the resource discovery and design the initial drilling program. However, in favourable circumstances a combination of limited infill drilling and bulk sampling by magnetic field inversion may provide a cost effective and superior means of defining the resource. We illustrate this with a study of the Hawsons magnetite deposit south of Broken Hill.