Reflectance spectroscopy in the VIS-NIR-SWIR region is particularly sensitive to clay and iron minerals that result from the weathering and oxidation of any type of geological materials - including sulfide- or iron-rich ore, outcrops, and/or mine waste.
Iron-bearing minerals are particularly useful in tracking sulfide oxidation and mine waste. The process of pyrite oxidation at the surface of mine waste can produce acidic water that is gradually neutralized as it drains away from the waste. This neutralization can deposit different Fe-bearing secondary minerals that zone away from mine-waste piles. These Fe-bearing minerals are indicators of the geochemical conditions under which they form.
Reflectance spectscopy - using either airborne or hand-held spectrometers - can be used to map secondardy Fe-mineral zones because each of these minerals is spectrally unique. In this way, imaging spectroscopy can be used to "rapidly screen entire mining districts for potential sources of surface acid drainage and to detect acid producing minerals in mine waste or unmined rock outcrops" (Swayze et al., 2000).