Identifying Minerals in Porphyry Copper Alteration Zones


NIR spectroscopy can be a valuable vectoring tool for mineral exploration in copper mining. Using an oreXpress™, oreXplorer™ or an oreXpert™ spectrometer and SPECTRAL EVOLUTION’S EZ-ID™ software can result in fewer drill holes and better results by identifying minerals in associated alteration zones.

Assemblages of alteration minerals associated with porphyry copper include:

  • Potassic alteration: k-feldspar, biotite, sericite, chlorite, quartz
  • Phyllic alteration: quartz, muscovite, pyrite, chlorite
  • Argillic alteration: kaolinite, dickite, muscovite, montmorillonite
  • Propylitic alteration: chlorite, calcite, epidote, pyrite, albite

With an oreXpress, oreXplorer or oreXpert spectrometer and EZ-ID mineral identification software, a geologist can identify minerals indicating copper in real-time, in the field. EZ-ID matches your samples against three spectral libraries of over 1100 minerals: the USGS, SpecMIN, and GeoSPEC libraries. EZ-ID allows the geologist to unmix the minerals in a sample using match regions to focus on specific absorption features and match only to those features. In addition EZ-ID provides the geologist with scalars. Spectral scalars can enhance the geologist’s understanding of crystallinity changes, alteration pattern shifts and geochemical conditions.

The oreXpress, oreXplorer and oreXpert deliver full range, UV/VIS/NIR capabilities from 350-2500nm, are lightweight, rugged, include integral autoexposure and auto-dark shutter, and are available with a rugged tablet with digital camera, GPS, and voice notes that can be tagged to your spectra.

In addition, our DARWin Data Acquisition software saves  your scans as ASCII files for use (without pre-processing) with third party software, including chemometric
analysis software. In addition, there is optional conversion of ASD files for use with
EZ-ID—save your existing libraries and databases.

Spectral Evolution field spectrometers for mining exploration

The oreXpress, oreXplorer and oreXpert are well-suited for in situ measurements and identification of minerals with EZ-ID software.

Identifying kaolinite with EZ-ID mineral identification software

EZ-ID identifies mineral samples by matching to three libraries of known mineral samples: the USGS, SpecMIN and GeoSPEC libraries of over 1100 minerals and 2600 spectra.