What is a meteorite slice?
A meteorite slice is a thin section cut from a meteorite with a diamond saw and usually polished, revealing internal features such as chondrules, metal grains, crystals or, in iron meteorites, the Widmanstätten pattern.
From the outside, most meteorites look like dark, rather plain rocks. Cut one open, though, and a hidden world appears. A slice is a flat piece sawn from a meteorite, typically a few millimetres thick, which is then ground smooth and polished so that its internal structure can be seen clearly. Slices are popular with collectors and are an important tool for scientists.
What you see depends on the type. A slice of an ordinary chondrite shows small round grains called chondrules, once molten droplets, along with bright flecks of iron-nickel metal set in a fine-grained matrix. A pallasite slice is one of the most beautiful objects in nature, with golden-green crystals of olivine set in shining metal; held up to the light, a thin slice can glow like stained glass. An iron meteorite slice, once lightly etched, reveals the criss-cross Widmanstätten pattern of interlocking metal crystals that grew as the metal cooled extremely slowly inside an asteroid.
Slices are cut with diamond-edged saws, usually cooled with oil or other fluids rather than water to avoid rust. Iron slices are etched with a dilute acid solution to bring out the pattern. This is skilled work using hazardous chemicals and must be done by experienced adults with proper protective equipment, never by children or at the kitchen table. For scientific study, specialists go further, cutting slices so thin, about 0.03 mm, that light shines through them, and examining these thin sections under a microscope.
Cutting does remove material, so it is a trade-off. Scientists usually preserve part of each meteorite uncut, and collectors often value specimens that show both a cut face and the natural outer crust. Once you have a slice, store it dry and handle it by the edges, because polished surfaces, especially iron ones, are easily marked by fingerprints.