Iron, IIC, plessitic Most Common type of iron meteorite, composed mainly of taenite and kamacite and named for the octahedral (eight-sided) shape of the kamacite crystals. When sliced, polished and etched with an acid such as nitric acid, they display a characteristic Widmanstätten pattern. Spaces between larger kamacite and taenite plates are often
Found August 1906
37° 44′ N., 89° 53′ W. An angular mass of 17.5 kg was found on the farm of Patrick Monaghan about one mile west of Perryville, Missouri. The mass was sticking out of the soil as if it had been previously disturbed by plowing. It has suffered from terrestrial weathering and lost an average of 1–2 mm from the surface, but still preserves sections of the heat-affected zone and retains evidence of Gradual removal of the successive surface layers of a material through various processes. • The gradual removal and loss of meteoritic material by heating and vaporization as the meteoroid experiences frictional melting during its passage through the atmosphere. The resulting plasma ablates the meteor and, in cases where a meteor Click on Term to Read More pits.
Diagram credit: Tornabene et al., 50th LPSC, #1236 (2019) To learn more about the relationship between this and other iron chemical groups, see Appendix III. The photo above shows a 11.5 g etched partial slice that displays kamacite spindles in a µm-sized Thomson (Widmanstätten) pattern. An ~1 mm shocked Brass colored non-magnetic Fe sulfide, FeS, found in a variety of meteorites. nodule is visible on this slice. These 0.1–2 mm nodules generally occur every 25 cm², rarely attaining a size of up to 8 mm. The photo below is from the National Museum, showing the original mass.