Research Chemistry

Scientific Issue and Relevance

Mineral assessments, ore deposit models, and studies of environmental and human-health impacts of mineralization are all underpinned by the ability to accurately determine concentrations of elements, chemical species, and minerals in complex samples. As a result, the success of many projects funded by the Mineral Resources Program (MRP) and Energy and Minerals Mission Area relies on the ability to obtain high quality, defensible data which requires access to state-of-the-art instrumentation and methods of analysis as well as advanced analytical expertise that are beyond the scope and capability of most individual projects and contract laboratories.

Methods to Address Issue

Scientists supported by Research Chemistry respond to the analytical needs of MRP and other USGS projects by developing analytical methods and maintaining state-of-the-art facilities and expertise over a broad range of geoanalytical techniques. Project members also develop methods for specialized analyses via reimbursable projects for other DOI and U.S. government agencies. Advances in analytical methods and approaches are shared with the scientific community through presentations and publications. 

Current Capabilties and Research Directions of Research Chemistry Facilities:

Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS): LA-ICP-MS measures concentrations of multiple trace elements in the solid phase without need for extensive sample preparation such as acid digestion. Multi element analysis can be performed at micron scale resolution with low limits of detection, allowing a detailed look at the chemical story preserved in minerals, rocks, and biological and environmental samples. The USGS LTRACE laboratory can provide collaborators with analyses on submitted samples or guide them through the analysis of their own samples.

Solution-Phase Inductively Coupled Plasma-Mass Spectrometry (SP-ICP-MS): The Aqueous Trace Element Analysis Laboratory (ATEAL) supported by the project focuses on multi-element measurements in the solution phase. The solution can be derived from a variety of sources including natural waters and digestion of solid samples. Sample preparation and introduction techniques can be developed to achieve extremely low detection limits and measure concentrations of different chemical species of the same element. ATEAL is equipped with both quadrupole and high-resolution magnetic sector ICP-MS instruments, an ICP-optical emission spectrometer, and a high-performance liquid chromatograph.

Aqueous and Single Element Analysis: The G3 Single Element Analysis Laboratory (G3SEAL) develops methods for single element analysis (e.g., selenium, tellurium) at very low detection limits. The lab also performs routine analyses of alkalinity by endpoint titration, anions by ion chromatography, and dissolved organic carbon by high temperature combustion. Samples for these analyses are submitted through the web-based sample submittal system hosted by the Analytical Chemistry Project.

X-ray Techniques: Task scientists improve current methods, develop new methods, and push the boundaries of X-ray mineral and elemental analysis in geological materials. Techniques included in this task are:

• Powder X-ray diffraction (XRD) for mineral identification and compositional analysis
• Wavelength dispersive x-ray fluorescence spectroscopy (WD-XRF) and Energy dispersive X-ray fluorescence spectroscopy (ED-XRF) for bulk elemental chemistry
• Handheld X-ray fluorescence spectroscopy (hXRF) for portable screening and in-field elemental analysis
• Specialized clay and amorphous (poorly-crystalline) phases analysis
• Development of USGS XRD analysis software and mineral database

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