Gold Exploration Using Field Portable SWIR

Gold exploration is and continues to be an important application for the mining industry. Geologists have taken advantage of SWIR (Short Wave Infrared) technology for mapping alterations in gold deposits since the early 1990’s and technology has become increasingly better since then. Utilizing a full range field portable spectrometer (350-2500nm), geologists can more accurately determine alteration type and quickly make a decision for vectoring purposes without the need to send samples and core to a lab for analysis. These instruments are essential for gold exploration due to their ruggedness and can be used in the field for mapping and mineral identification. Examples of gold deposits include:

An example of low sulfidation spectral data is shown in Figure 1 – as a geologist measures down a core, the presence of Kaolinite (indicated by red, green and blue spectra) and White Mica (Illite indicated by the purple spectrum) are apparent. This type of data is used as a vectoring tool for Geologists to indicate what area of the centralized core or inner/outer halo the current sample is from and how close they are to the target. This is done by monitoring the spectral shifts or occurrences of specific mineral assemblages and chemical/temperature changes of alteration minerals like kaolinite, white mica and chlorites.

Figure 1: Spectral data from oreXplorer
Data provided by or courtesy of J&J Exploration, LLC and Durfeld Geological Management

With Spectral Evolution’s oreX™ series spectrometers and EZ-ID™ software, geologists can scan and identify common alteration minerals, such as:

• For low sulfidation: illite, kaolinite, chlorite, illite/smectite, buddingtonite, epidote, montmorillonite, zeolite, quartz, calcite, hematite
• For high sulfidation: alunite, opal, dickite, pyrophyllite, diaspore, zunyite, topaz, illite, kaolinite, chlorite, epidote, quartz, montmorillonite, goethite, jaosite, hematite
• For orogenic gold: muscovite, paragonite muscovite, roscoelite, illite, kaolinite, quartz, siderite, ankerite, calcite, dolomite, carbonates

Using EZ-ID with the USGS spectral library, the SpecMIN™ library, or the GeoSPEC library, the software quickly provides accurate matching of an unknown target with a known mineral spectra. With an oreX series spectrometer and EZ-ID a geologist can identify minerals indicating gold in real-time, in the field.

Benefits include:
• Quickly collect a lot of scans
• Cover more ground in less time for better mapping
• Collect more accurate data for a more complete picture of the area you are exploring
• Get results immediately instead of waiting for lab analysis
• Drill fewer holes with better results
• Speed-up core shack scanning and logging, accurately identify samples of interest, and save on assay costs

With Spectral Evolution field portable UV-Vis-NIR spectrometers and EZ-ID mineral identification software, geologists can measure and identify minerals within seconds and cover more ground than by using traditional methods. They can identify different mineral phases, create mineral alteration maps and more accurately identify mineral pathfinders for vectoring to ore deposits. Spectral Evolution’s field portable, battery-operated oreXpress™, oreXplorer™ and oreXpert™ ultra-high resolution UV-Vis-NIR spectrometers provide quick payback with faster, more accurate mineral identification in exploration for gold, silver, diamonds, iron, nickel, copper, uranium, aluminum – in the field, core shack, or in the lab.