Porphyry Cu-Mo Alteration with SWIR

Copper is a critical resource used in technology ranging from electronics to infrastructure. The largest, most valuable and profitable copper mines are historically large-scale porphyry deposits. Due to their geologic setting, it is critical to have an efficient and accurate way of identifying alteration zones of porphyry Cu-(Mo). SWIR spectroscopy is an ideal technique for studying these alteration zones. It has proven to be very useful for mapping alterations, particularly white micas, clays, chlorites, sulfates, and iron oxides. SWIR data can also be used to track the replacement of feldspar by clays (kaolinite, smectites, and illites).

The ore-X™ series from Spectral Evolution delivers full-range UV/Vis/NIR capabilities from 350-2500nm. These portable instruments are the most accurate spectrometers on the market. Lightweight and rugged, they are designed to resist the most demanding conditions of the mining environment with no sample preparation needed. In addition, our DARWin™ Data Acquisition software saves your scans as ASCII files for use (without pre-processing) with third-party software, including spectral and chemometric analysis software. Combined with the EZ-ID™ mineral identification software and our spectral library builder, geologists can now accurately identify minerals on site, instantly, within seconds.

In this study we show samples of porphyry alterations and their corresponding spectral data provided by University of British Columbia’s MDRU (Mineral Deposit Research Unit) that show potassic alteration, sericitic alteration and sericitic-chloritic alteration.

Samples A-D (Figures 1, 3, 5, 7) show a 3mm blue circle that indicates the area of measurement taken by the oreXpert™ field spectrometer. Figures 2, 4, 6, 8 shows the spectral data imported into Spectral Evolution’s EZ-ID™ mineral identification software tool where the minerals are identified.

By using field spectrometers within the ore-X series line with EZ ID, geologists can effectively identify different porphyry alterations. This exemplifies the usefulness of the ore-X series for the mapping of porphyry alterations and copper deposits. Examples like this make Spectral Evolutions instruments an excellent choice for your geologic mapping needs.