Mountain Pass, California (USA), located in the eastern Mojave Desert, hosts one of the world’s richest rare earth element (REE) deposits. The REE-rich terrane occurs in a 2.5-km-wide, northwest-trending belt of Mesoproterozoic (1.4 Ga) stocks and dikes, which intrude a larger Paleoproterozoic (1.7 Ga) metamorphic block that extends ∼10 km southward from Clark Mountain to the eastern Mescal Range. To characterize the REE terrane, gravity, magnetic, magnetotelluric, and whole-rock physical property data were analyzed. Geophysical data reveal that the Mountain Pass carbonatite body is associated with an ∼5 mGal local gravity high that is superimposed on a gravity terrace (∼4 km wide) caused by granitic Paleoproterozoic host rocks. Physical rock property data indicate that the Mountain Pass REE suite is essentially nonmagnetic at the surface with a magnetic susceptibility of 2.0 × 10−3 SI (n = 57), and lower-than-expected magnetizations may be the result of alteration. However, aeromagnetic data indicate that the intrusive suite occurs along the eastern edge of a distinct northwest-trending aeromagnetic high along the eastern Mescal Range. The source of this magnetic anomaly is ∼1.5–2 km below the surface and coincides with an electrical conductivity zone that is several orders of magnitude more conductive than the surrounding rock. The source of the magnetic anomaly is likely a moderately magnetic pluton. Combined geophysical data and models suggest that the carbonatite and its associated REE-enriched ultrapotassic suite were preferentially emplaced along a northwest-trending zone of weakness, which has potential implications for regional mineral exploration.

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Increasing radiologic exam volume and complexity necessitates leveraging advanced hardware solutions to optimize workflow efficiency. We evaluated radiologist satisfaction of a programmable 13-button non-conventional mouse compared to a conventional three-button mouse in daily interpretation workflow following a brief 2-day trial period. A prospective study was conducted with radiology staff and residents in a tertiary care center from 2015 to 2016. A survey was distributed prior to and after a tutorial and a 2-day non-conventional mouse trial period. The post-survey evaluated usage time, device settings, satisfaction, preferences, and perceived efficiency of both mice. Descriptive analyses, correlations, the Sign test, and the Wilcoxon signed-rank test were used to evaluate responses. Fifty-nine participants completed pre- and post-surveys. Several (41%, n = 24) had prior experience with a non-conventional mouse. Prior to the trial, one third of all participants (35.6%, n = 21) reported being satisfied or very satisfied with their conventional mouse. After spending an average of 9.8 h using the non-conventional mouse, there were no statistically significant changes in overall satisfaction with either conventional or non-conventional mice (p = 0.84 and p = 0.39, respectively). However, 76.3% (n = 45) agreed/somewhat agreed they preferred to use the non-conventional mouse in their daily workflow as opposed to the conventional mouse. The non-conventional mouse was also perceived as more efficient (66.1%, n = 39), required less time (62.7%, n = 37) and effort (74.6%, n = 44) to view images, allowed for easier manipulation of windows/images (76.3%, n = 45), and was more comfortable to use (78.0%, n = 46). Although there were no statistically significant shifts in overall satisfaction, participants reported a higher level of satisfaction, perceived efficiency, and preference for a non-conventional 13-button mouse compared to a conventional three-button mouse following a brief, 2-day trial period.

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SUMMARYThe southeast Mojave Desert hosts one of the world's largest rare earth element (REE) deposits at Mountain Pass, California. Although surface geology has been studied, a full understanding of the carbonatite and associated intrusive suite complex requires subsurface geophysical characterization. In this study, a combination of geophysical methods, including magnetotelluric (MT), magnetics, and gravity are used to create a two-dimensional (2D) geophysical model to a depth of about 10 km. An electrically conductive body is found 2-3 km below and west of the deposit that is associated with a magnetic high that could be connected to a deeper (10 km) conductive body related to possible intrusions or hydrothermal systems. The carbonatite body coincides with a steep magnetic gradient and a bench or terrace in the gravity data that may reflect relative lower-density intrusive rocks. Although carbonatite rocks are typically magnetic, the carbonatite rocks, associated intrusive suite, and host rocks in this area are essentially non-magnetic. Combined geophysical data indicate that the enriched REE deposit may be related to a regional extensive hydrothermal alteration event.