Measuring Mica Alteration

Identifying the alteration path from montmorillonite through smectite/illite, illite, sericite, muscovite to a potential ore zone can be a complicated process even for an experienced geologist. The oreXpress field spectrometer with EZ-ID mineral identification software can identify these “white micas” and provide critical data for alteration mapping.

As the minerals alter from smaller to greater percentage of aluminum hydroxide, the change can be seen in spectral shifts at the 2200nm wavelength. With EZ-ID and access to more than 1500 mineral spectra in the USGS and SpecMIN mineral libraries, a geologist can examine the best matches to known samples of the minerals and accurately determine a vector to mineralization.

With an oreXpress geological spectrometer and EZ-ID, the user can identify:

  • Montmorillonite
  • Smectite
  • Illite
  • Sericite
  • Muscovite
  • Phengite

Every oreXpress includes our DARWin SP Data Acquisition software and is available with EZ-ID and the Custom Library Builder Module. EZ- ID allows you to compare your target sample with a known library of mineral spectra. EZ-ID comes with the USGS spectral library and is available with the SpecMIN library from Spectral International. The USGS library contains 466 spectra for 226 minerals, while SpecMIN has 1528 spectra for 500 minerals. With both libraries, a geologist has access to a wide range of possible matches for exploration projects.

EZ-ID features:

  • Fast and accurate identification of an unknown mineral to a known spectral library sample
  • Ease-of-use: take your scan using an oreXpress and see results in real-time
  • Simple, consistent user interface
  • USGS and SpecMIN libraries available
  • Weighted score for best matches
  • Include or exclude spectral regions of interest for optimal results

Using an oreXpress with EZ-ID delivers the following benefits for exploration geologists:

  • Quickly take a lot of samples
  • Cover more ground in less time
  • More accurate data provides a more complete picture of what you are looking at
  • Less time and expense than waiting for samples to come back from the lab
  • Less drilling – better results – quickly delivers a return-on- investment

In the field the oreXpress is rugged, reliable, and designed for single user operation. Field collection of spectra is fast and accurate. In the core shack, a single geologist with a contact probe could log as much as 400 meters a day. And, since DARWin saves it all in an ASCII format, it’s easy to use the data with 3rd party software for mine mapping, mineral mapping and 3D imagery.

oreXpress field portable spectrometer for mineral identification

SPECTRAL EVOLUTION’S EZ-ID software has identified our target sample as montmorillonite using the SpecMIN spectral library for reference. The shaded areas shown in the scan allow a geologist to concentrate on regions/wavelengths in the spectra of particular interest.