This paper will be presented at the Art, Science and Applications of Reflectance Spectroscopy Symposium sponsored by ASD Inc. and IEEE GRSS, February 23-25, 2010 in Boulder, Colorado.

Authors: Brian Curtiss¹, Phoebe Hauff²
Affiliations:
(1) ASD, Inc., Boulder, CO  USA
(2) Spectral International, Inc., Arvada, CO  USA

Abstract
Reflectance spectroscopy is widely used in the mining industry to identify new deposits as well as to provide information that supports ore sorting and processing decisions. In exploration, reflectance spectroscopy allows for rapid characterization of many individual minerals and alteration assemblages associated with economic mineral deposits. Since alteration can extend beyond an economic deposit, mapping of alteration zones provides a useful vector to the predicted mineralization.

Deposit types such as epithermal gold, porphyry copper, diamonds, uranium, rare earths, base metals all have diagnostic mineral signatures that define alteration assemblages and distribution producing deposit models. Knowledge of these models allows the explorationist to better evaluate type and potential of a prospect.

Mineral maps are created from satellite and airborne sensors. The alteration identified is field checked with portable spectrometers. It allows rapid, insitu identification of minerals at the outcrop and in the core. High volumes of samples are processed faster then other analytical methods. Accurate alteration models can be constructed which aid in drilling programs. Reflectance spectroscopy has literally revolutionized how exploration is done.

In active mines, reflectance spectroscopy is often used as a laboratory technique to supplement XRD analysis and other measurements of blast-hole cuttings for metallurgical processing decision making. Reflectance spectroscopy is used to measure ore properties such as acid consumption, abundance of swelling clays, and fines all of which are important for optimizing heap leach operations. The advantage of reflectance spectroscopy is the speed of measurement and the need for minimal sample preparation. For exploration, direct measurements of outcrop, cores and RC chips are all common applications. For operating mines, it is possible to perform quantitative ore analysis on either coarse or finely ground samples, such as assay pulps. Quantitative calibrations built using coarse samples may be used both for laboratory analysis as well as in fixed over-the-conveyor installations.