PAVING THE ROAD TO ROUTINE RAMAN MINERAL IDENTIFICATION

Raman spectroscopy has opened new windows into the worlds of mineralogy, petrology, geochemistry, geobiology and planetary science. Although long appreciated for use in phase identification, wide availability of modern Raman instruments is now revealing its full potential as a fast and flexible tool for every-day routine search/match phase identification. In recognition of the rapidly growing interest in using Raman for mineral identification, we are assembling a “Practical Guide” for routine Raman analysis of mineral samples, and efforts are underway to build a comprehensive, curated and supported search/match reference library of mineral Raman spectra for the user community.

In addition to essential principles and how-to instructions, the Practical Guide provides instrument-performance and data-collection guidelines generated using real spectra and simulating the impacts of variations in spectral resolution, pixel resolution, spectral calibration, and signal-to-noise ratio on mineral-identification success.

The reference library builds upon the current and well-regarded RRUFF database by adding additional spectra with supporting practical mineral-identification as the objective. As part of a strategy to improve the success for mineral identification, a “mineral-importance” scale was generated by combining a) locality counts from MINDAT, b) request lists from practicing mineralogists and petrologists, and c) ore-mineralogy information on today’s critical minerals from USGS Professional Paper 1802. This scale provides one way of ranking the more important minerals according to their scientific and commercial interest and serves as a priority guide for adding spectra to the library. We see this as the start of a sustained effort to collect Raman reference spectra from well-characterized samples to expand and enhance an expertly curated and supported mineral Raman spectra reference library, available and supported by the International Center for Diffraction Data (ICDD), an entity with decades of experience managing and building critical reference databases, with a mission to ensure their long-term integrity, management, and availability to the user community.