promotes the development of natural resources Some of the ores produced from impact-related effects on Earth include ores of iron, uranium, gold, copper, and nickel. It is estimated that the value of materials mined from impact structures is 5 billion dollars/year just for North America. Direct evidence for useful materials It has for some time been accepted by the scientific community that a group of meteorites came from Mars. As such, they represent actual samples of the planet and have been analyzed on Earth by the best equipment available. In these meteorites, called SNCs, many important elements have been detected. Magnesium, Aluminium, Titanium, Iron, and Chromium are relatively common in them. In addition, lithium, cobalt, nickel, copper, zinc, niobium, molybdenum, lanthanum, europium, tungsten, and gold have been found in trace amounts. It is quite possible that in some places these materials may be concentrated enough to be mined economically. The Mars landers Viking I, Viking II, Pathfinder, Opportunity Rover, and Spirit Rover identified aluminium, iron, magnesium, and titanium in the Martian soil. Opportunity found small structures, named "blueberries" which were found to be rich in hematite, a major ore of iron. These blueberries could easily be gathered up and reduced to metallic iron that could be used to make steel. In addition, both Spirit and Opportunity Rovers found nickel-iron meteorites sitting on the surface of Mars. These could also be used to produce steel. In December 2011, Opportunity Rover discovered a vein of gypsum sticking out of the soil. Tests confirmed that it contained calcium, sulfur, and water. The mineral gypsum is the best match for the data. It likely formed from mineral-rich water moving through a crack in the rock. The vein, called "Homestake," is in Mars' Meridiani plain. Homestake is in a zone where the sulfate-rich sedimentary bedrock of the plains meets older, volcanic bedrock exposed at the rim of Endeavour crater. Dark sand dunes are common on the surface of Mars. Their dark tone is due to the volcanic rock called basalt. The basalt dunes are believed to contain the minerals chromite, magnetite, and ilmenite. Since the wind has gathered them together, they do not even have to be mined, merely scooped up. These minerals could supply future colonists with chromium, iron, and titanium. Future detection for ores on Mars Theoretically, ore resources exist on Mars. Moreover, sensitive equipment can predict where to look for them, such