Enhanced Weathering (EW) of silicate rocks is viewed an essential methodology for scaling carbon dioxide removal (CDR) to reach goals of negative global CO2 emissions. EW has an equally important potential for improving agricultural soil, increasing crop yields, and reducing traditional fertilizer use and associated waste. Of all potential silicate raw materials for EW basaltic (mafic) rocks have perhaps the greatest potential, even though the total amount of CDR per unit is less than pure minerals like olivine. Basaltic rocks are widespread compared to other lithologies, are proven to benefit degraded agricultural soils, have significant CDR potential, and minimal negative environmental impacts including heavy metals. Systematic approaches to select basaltic raw material for agricultural and CDR benefits include petrographic and XRD analyses of minerals, XRF and ICP-MS analyses of major and trace elements and grainsize analysis of primary milled material or byproduct material from other aggregate uses. Analysis of commercially available “basalt” shows a wide range in relative quality in terms of primary mineralogy, chemical composition, degree of alteration and metamorphism, achievable grain size, proximity to low carbon transportation and application sites, climate, soil type, and other economic factors. Some products advertised as basalt are dark colored felsic rocks (andesite, dacite) or metamorphosed mafic rocks all of which have lower potential for CDR. These factors limit potential sources of basalt to a small percentage of quarry locations. Mafic, basaltic rocks have SiO2 contents between 45 and 52 percent and vary widely in percentages of mineral phenocrysts– e.g. olivine may range from 0 to >5%, which are also factors in selection of raw material. From an agricultural perspective, analyses of water extractable and Mehlich-3 nutrients reveal values less than the totals of primary unweathered basaltic material; these values increase with degree of EW. Widespread adoption of EW methods for improving soil health will require local and regional crop specific trials and realistic guidelines for application rates and grain sizes that are practical and economic for producers. Characterizing raw material is paramount to instilling confidence in CDR potential and benefits for crops and soil health.