Mineral wireline logging, which is really an offshoot of oilfield wireline logging, is a process in which an electronic tool, probe or “sonde” is lowered into a borehole in order to make measurements of physical rock mass properties and borehole trajectory, structural setting and fluid properties Measurements employ electro-magnetic fields (directly or induced), radiation (natural and introduced via a chemical source) and sonic energy to interrogate the rock mass without physically breaking it. 

The sonde is lowered on a cable or “wireline” which transmits both power to the sonde and data from it to the surface recording systems. The data is proportional to analogue voltages produced by the various detector types. It must be calibrated and compensated for borehole effects in order to become a quantitative measurement. Examples are natural gamma ray, density, sonic transit time and resistivity.

Logs might describe or estimate the lithology, the local structure, rock strength, borehole direction and various fluid parameters such as temperature and conductivity. Wireline logs are routinely used in mineral exploration to describe coal seams in terms of depth, thickness and ash content. They have applications in all forms of mineral exploration, including base and precious metal projects

Wireline’s role, as well as capturing log data, is to increase the value gained from drilling projects by assisting in the choice of applicable measurements, operational planning, calibration, data processing, analysis, presentation and reporting.