The above calibration curves were based on the best possible sample surface and instrument geometries: smooth uniform surfaces enabling complete contact between the instrument and the sample surface. However, field applications present less ideal and more variable sample surface geometries, making sample presentation an issue that will affect data quality. The miniaturization of the X-ray tube and detector technologies have resulted in challenges in detecting lower energy X-rays. To lessen the challenges of detecting these lower energy elements, minimizing the distance between the detector (and therefore the prolene window) and the sample of interest is crucial. Sample surface heterogeneities introduced, for example, when breaking off a sample in the field with a rock hammer, have the same effect of increasing the instrument working distance. Sawed samples present the ideal case of a perfectly smooth sample for presentation to the instrument window. However, this amount of sample preparation is not possible in a field setting. It is therefore important to understand the implications of varying surface roughness on data quality. In order to illustrate this effect, we show data collected from the laboratory XRF as well as data we collected using the hXRF, but the hXRF data are shown in two groupings: for surfaces that are sawed, and for rough surfaces (though all data was collected on fresh surfaces with no weathering or alteration products) (Fig. 3aee).