BACKGROUND

Reflectance spectroscopy in the visible, near and shortwave infrared (350- 2500nm) has been employed to study the spectral mineralogy of regolith materials. It has the advantage of being sensitive to both crystalline and amorphous materials, unlike some other diagnostic methods like X-ray diffraction (Clark 1999). However, the reflectance measured can be affected by sample preparation, particle size, sample concentration and optical geometry. CRC LEME, in collaboration with Genalysis Laboratory Services, has investigated the effects of some of the routine laboratory treatments on spectral mineralogy, such as drying, crushing and pulping (particle size). In one specific study, regolith materials from a diamond drill intersection taken from the Jaguar Cu-Zn-Ag deposit, 4 km south of Teutonic Bore in the Eastern Goldfields Province of the Yilgarn Craton, were used. The main ore body is approximately 250 m below surface. The regolith materials, spanning a depth of 130 m, comprise colluvium-alluvium overlying saprolite, saprock and bedrock (basaltic composition). All of the samples were dried at 121°C before crushing and pulverising due to the presence of moist clay in the regolith samples that cause problems during preparation. The regolith materials were crushed to approximately 2 mm, to simulate chips, using a Boyd crusher and rotary sample splitter. One half of each sample was left as chips while the other half was pulverised to <75 um. Since all the samples in this study were dried, only tw