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Comb plessite |
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| Meteorite - Carbo, IID Iron |
| Plessite is a fine-grained mixture of kamacite
and taenite, often containing minor amounts of schreibersite and tetrataenite.
Rather than being a simple mineral, plessite is a complex term describing the
diverse structural patterns that frequently form between kamacite and taenite
lamellae. This two-phase mixture represents the final stage of development from
retained taenite during the primary cooling process. Plessite fields are visually striking and are typically bordered by a continuous taenite rim. Larger plessitic fields, known as comb plessites, develop under extremely slow primary cooling conditions and exhibit a distinctive structure resembling the teeth of a comb. The Carbo meteorite, classified as a IID iron, provides an example of this phenomenon. Its primary cooling rate is estimated to have been between 10°C and 20°C per million years. In this context, plessitic fields are regarded as secondary structures, with their alignment closely tied to the host Widmanstätten pattern. |
| Figure 1. Scale bar 900 µm. |
| Comb plessite, Carbo, Iron, IID. |
| Listing of Structures |