NTGS rock property data collection methodologies

Abstract

This Technical Note documents three methods used by the Northern Territory Geological Survey (NTGS) to collect rock property data from drill core and other rock samples. Standardised methods are used to ensure the rock property measurements are consistent and repeatable. The three methods used and their resultant rock property measurements are:

Archimedes' method for bulk density, grain density and porosity;

vacuum sealing method for bulk density; handheld magnetic susceptibility meter method for magnetic susceptibility.

The repeatability of the Archimedes' method and the vacuum sealing method is monitored through regularly cross checking bulk density results obtained using the two different methods. Bulk density measurements using the two methods are generally consistent with 95% of measurements correlating to within 0.10 g/cm3.

The repeatability of the handheld magnetic susceptibility meter method is monitored through the use of magnetic susceptibility standards. Measurements of these standards are taken twice daily; 95% of the KT-20 S/C measurements are within 1.1% of the average magnetic susceptibility of the calibration standards. Likewise, 95% of the KT-9 measurements are within 3.1% of the average magnetic susceptibility of the calibration standards.