Chemical Analysis
What is the evidence? Detection of the elements or compounds that make up rocks and minerals, or even the atmospheres of planets
What does it tell us? Origin of a rock or how different rock samples may be related; atmospheric composition of a planet
Key limitations: Sample access and availability
Example: Iron Meteorite
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Chemical analysis can determine whether a rock came from outer space. On Earth, naturally occurring rocks that contain nickel or iron metal are very rare. Most meteorites, however, contain at least some iron and nickel. Stony meteorites—the most common—contain small amounts of iron and nickel metal. A typical stony meteorite, for example, contains ~6 to 19 percent iron and 1 to 2 percent nickel. Iron meteorites—most of which likely came from the cores of asteroids—contain very high amounts of iron and nickel. The photo shows Campo del Cielo, an iron meteorite that fell in Argentina. It consists primarily of iron (92.7%), nickel (6.15%), cobalt (0.42%), carbon (0.37%) and phosphorus (0.28%), with trace levels of silicon, titanium, vanadium, gallium, copper, and sulfur.
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