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Regmaglypts |
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Figure 1. Scale bar 1.5 cm. |
| Meteorite, Sikhote-Alin, Iron, IIAB |
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| Regmaglypts are
thumb-like depressions or pits seemingly carved into the surface of meteorites
by turbulent supersonic airstreams during atmospheric flight and
deceleration. Occasionally seen on stone meteorites, they are a specific hallmark of an iron meteorite. Once believed to be caused by the disruption and burning of low-temperature melting minerals, such as troilite or schreibersite in the meteoroid, it is now accepted that these depressions occur as the meteoroid passes through the atmosphere. A meteoroid moving through the vacuum of space can travel at speeds of tens of thousands of miles per hour. Entering the Earth's atmosphere, in only a couple of minutes, its exterior surface can reach high temperatures upwards to 3,000° F (1,650° C) from the air molecules in front of it compressing, resulting in friction and heat. An iron meteorite's dominant mineralogy is kamacite, taenite, and, to a lesser degree, cohenite, schreibersite, and troilite.Their melting points are: Kamacite 1,500° C. Taenite, with 30 - 40% Ni in solid solution, 1,460° C to 1,470° C. Cohenite (a carbide mineral), 1,400° C. Schreibersite (an iron-nickel phosphide), 1,000° C. Troilite (an iron sulfide), 990° C. Note that graphite has a melting point of 3,600° C. However, it only occurs at trace levels in irons. The atmospheric passage is a violent ride at the above-described velocities and temperatures. Regmaglypts are a logical conclusion of the phenomena of atmospheric entry and passage. Additionally, ablation, atmospheric entry angle, velocity, time in the atmosphere, tumbling, or orientation are a few more topics to consider in any study of regmaglypts. |
Figure 2. Scale bar 1.5 cm. |
| Meteorite, Gibeon, Iron, IVA |
| Regmaglypts |
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Figure 3. Scale bar 0.8 cm. |
| Meteorite, Pultusk, Stone, H5 chondrite |
| Regmaglypts |
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Figure 3. Scale bar 0.9 cm. |
| Meteorite, Sikhote-Alin, IIAB, Iron, IIAB |
| Regmaglypts |
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