Serpentines have a range of accessory minerals (talc, chlorite, pyroxene, feldspars, olivine) due to variable hydrothermal alteration and/or composition of the original rock. These accessory minerals vary in their susceptibility to weathering and ultimately affect soil properties. Serpentinite-derived soils are of interest for their unique edaphic qualities (associated metals and low calcium) making them valuable as natural end-members of adverse conditions in ecological, agricultural and reclamation studies. We hypothesized that soils formed on what is nominally referred to as serpentinites vary as a result of variability in the parent material. Eleven pedons have been sampled from Henneke soil series (Clayey-skeletal, magnesic, thermic Lithic Argixerolls) map units from California. The soil NH4-acetate extractable Ca:Mg ratios range from 0.01 to 1.5. Total elemental analysis of the parent materials from these profiles varies greatly in total concentrations of Al2O3 (0.3-15%), CaO (0.02-23%), MgO (5-36%), and Fe2O3 (8-20%). We used optical mineralogy and X-ray diffraction to identify accessory minerals related to soil Ca:Mg variability. We used Vulpia microstachys as a phytoindicator to assess how Ca-bearing minerals in the serpentines affect Ca and Mg uptake by plants.