27 Geological Surveys and Resource Mapping/Evaluation Studies (Posters)

This session highlights studies from state geologic surveys and the U.S. Geological Survey regarding natural resource evaluations. We welcome submissions with relevance to critical minerals, rare earth elements, various energy sectors, and the construction industry.

Tuesday, 10 March 2026
9:00 AM - 5:00 PM
RCC, Lower Level Hall

Initial Scanning Electron Microscopy of Macrocrystalline Gold from Eugene Mountains Nevada, Reveals Unexpected Complexities.

Paper number: 27-4
Program: Technical Sessions
Time: 9:00 AM – 9:00 AM

Authors

Abstract

Gold is an important resource and its value has greatly increased over the last 25 years by approximately 1,000% with the most recent prices being well over $4,000 an ounce. Understanding the mechanisms of gold mineralization is critical to exploration and developing refined gold extraction techniques. Nevada is a major gold producer globally with several recognized gold deposits. Macrocrystalline gold is comparatively rare however and its exact mechanisms are poorly understood. Samples of purchased macrocrystalline gold crystals from the Eugene Mountains, Humboldt County, Nevada were investigated with SEM to better understand the nature of crystallization using comparative criteria of Sunagawa and compare complexity of surface textures to other examples of macrocrystalline gold in Nevada. For example, Round Mountain macrocrystalline gold generally has well crystallized hopper and polyhedral surface textures that appear to align with classical growth models but are largely composed of nanoparticles in the interior. Initial SEM of the Eugene Mountain sample material indicates that surface textures are very diverse. Sample material seems to have a macroscopic millimeter scale hopper texture that has a somewhat uniform gold growth over it, indicated by partially closed gaps and other textures. Also, weakly expressed finer hopper growth textures are evident in some areas. Damage to the crystal is evident in some minor areas, and is likely due to past handling. Composition of the gold is likely close to electrum based on repeated well defined particles and lines of silver. Calcite and Ca are evident in some areas of the sample material. Because the overall composition is similar to macrocrystalline gold investigated from Round Mountain, future work using TEM can further compare these similarities. Results also provide constraints on comparing quality of native gold crystals in general for collectors and distinguishing between natural growth textures and forgeries of large gold crystals.   

 

Geological Society of America Abstracts with Programs. Vol. 58, No. 1

doi: 10.1130/abs/2026SE-411624

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