Jake Matijevic (rock) consistent with feldspar, such as sodium, aluminum and potassium, and lower concentrations of magnesium, iron and nickel than other such rocks previously found on Mars. The mineral content and elemental abundance indicates "Jake M" rock may be a mugearite, a sodium rich oligoclase-bearing basaltic trachyandesite. Igneous rocks similar to the "Jake M" rock are well known but occur rarely on Earth. On Earth, such rocks form when magma, usually found in volcanoes, rises to the surface, cools and partially solidifies with certain chemical elements, while the warmer liquid magma portion becomes enriched with the left-behind elements. By remarkable coincidence, the
Tholeiitic magma series distinguished from rocks in the calc-alkaline magma series by the redox state of the magma they crystallized from (tholeiitic magmas are reduced; calc-alkaline magmas are oxidized ). When the parent magmas of basalts crystallize, they preferentially crystallize the more magnesium-rich and iron-poor forms of the silicate minerals olivine and pyroxene, causing the iron content of tholeiitic magmas to increase as the melt is depleted of iron-poor crystals. However, a calc-alkaline magma is oxidized enough to precipitate significant amounts of the iron oxide magnetite, causing the iron content of the magma to remain more steady as it cools than with a