Compositionally, lava from the Newberry Volcano has varied from primitive basalts with high magnesium levels to more evolved tholeiitic and calc-alkaline deposits (based on the major element characteristics of the lavas). Primitive lavas exhibit high abundances of chromium and nickel as well as variable concentrations of fluid-mobile elements like barium and strontium. Tholeiitic and calc-alkaline lavas display overlap in magnesium, calcium oxide, and aluminum oxide levels but differ in that the tholeiites have lower contents of silica and potassium oxide and higher iron(II) oxide, titanium dioxide, and sodium oxide. There is also much overlap in isotopic composition, though the tholeiitic lavas mark the low point for 87Sr/86Sr and the high point for 143Nd/144Nd and 176Hf/177Hf. Examination of Newberry lavas with olivine-plagioclase hygrometry shows that tholeiites are anhydrous (less than 0.5 percentage by weight water) and thus distinct from calc-alkaline deposits 2-4 percentage by weight water); both have different fractional crystallization sequences that derive from primitive magmas, which had their compositions influenced by equilibrium with peridotite in the mantle. By volume, basaltic andesite is the principal lava type at Newberry Volcano, with large volumes of silicic lava among older ash flow tuff deposits.