Mineralogical and dimensional characterization of EMPs destined for biological experimentation

Abstract

Mineral specimens and mineral reference materials should be understood to be mixtures of various mineral species and the properties of each individual species will likely represent a range of quantifiable values and qualitative characteristics. The use of incompletely characterized mineral specimens may introduce significant uncontrolled variables in any experiment. Any mineral characterization should include an understanding of the bulk properties of the specimen as well as microanalytical and crystallographic characterization of individual mineral phases. This characterization should comprise a range of length scales to accommodate naked-eye level observations up to electron microscopic observations and analyses. Large spatial scale observations are useful to describe the physical properties of the material and understand the scale of inhomogeneities that may be present in a mineral sample. Microanalysis provides critical compositional and crystallographic information for mineral identification. It is critical to recognize where gaps might exist in the data produced during the characterization of a material and if those gaps are critical to evaluating the effect those minerals might have on the result of a given experiment. Likewise, it is critical to understand the interplay of various minerals that might be present in a sample other than the specific mineral of interest. The accessory minerals that are present, even if only trace amounts, could have a major impact and need to be isolated, or their impact accounted for in the interpretation of results. Dimensional characterization of particulate produced from a mineral specimen is important, but not as simple a task as it might appear. Dimensional data can be produced through any of several microscopic techniques, each with specific limitations and potential to be biased due to sample preparation technique. This understanding of the full composition of a mineral specimen cannot be obtained through rudimentary examination and it cannot be taken for granted that it has been performed by the supplier of the specimen.