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
West Crater imply that they resulted from the same movement of magma and were possibly fed by the same magma chambers. The lava dome likely formed before the lava flows erupted, suggested by its steep western side and the appearance of rock from the dome on the western lava flow. The dome's deep depression may have formed when the dome's top collapsed as lava moved out of the volcano during the eruption of the two flows. The human population within of West Crater is slightly more than 500 people, but more than 14,000 people live within of the volcano, and more than