An overview of vis-nir-swir field spectroscopy - Spectral International

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were designed more for general remote sensing with solar illumination as the
prime light source. It was the appearance of the ASD TerraSpec in 2004 with
its flexible and innovative design specifically for minerals and mining that has
brought cutting edge, fast, fiber-optic data collection into the field and core shack.
This paper will review the concepts of reflectance spectroscopy, and look at the
more practical information that can be obtained from the visible, near-infrared,
and short-wave infrared regions of spectra, beyond just simple mineral
identification. Routine applications such as core logging, field reconnaissance,
pit mapping, and remote sensing ground truth will be illustrated with examples.
Selected alteration systems for gold, porphyries, diamonds, unconformity
uranium, IOCGs and skarns will be summarized from a spectral perspective and
mini-case studies discussed, space permitting.
REFLECTANCE SPECTROSCOPY
Spectroscopy is the study of the interaction between energy as electromagnetic
radiation (EMR) and matter. Radiation can be absorbed, emitted or scattered by
matter.
Reflectance spectroscopy can be defined as the technique that uses the energy
in the Visible (0.4-0.7), Near-Infrared (0.7-1.0) and Short-Wave Infrared (1.0-2.5
µm) wavelength regions of the electromagnetic spectrum (Figure 1) to analyze
minerals.
Figure 1. – Highly generalized cartoon of the EMS showing the various regions that
are covered by field portable spectrometers. Source unknown.
The science and techniques of reflectance spectroscopy are based on the
spectral properties of materials. Certain atoms and molecules absorb energy as
a function of their atomic structures. (Hunt, 1977 and Goetz et al, 1982).
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