SEYMCHAN — ETCHED PARTIAL SLICE WITH CHROMITE
Estimation : 2500 - 4000 USD
Résultat : 3 048 USD
As the vast majority of iron meteorites are prosaically shaped, an opportunity exists to showcase their internal crystalline splendor by fashioning cubes, spheres, slices and the partial slice now seen. Seymchan meteorites were first found in a part of Siberia made infamous as the remote location of Stalin’s gulags and were named after a nearby town. While Seymchan is a pallasite, unlike most pallasites, the dispersion of olivine crystals in Seymchan is extremely heterogeneous. Some specimens are olivine rich (see lot 36), some are olivine poor (see lot 10) and some have no olivine at all. This is an example of the latter. The crystalline latticework seen here is most often referred to as a Widmanstätten pattern in honor of the second person to have noticed it. It is indicative of an extremely slow cooling rate that provided sufficient time — millions of years — for the two primary iron alloys in iron meteorites to orient into their present crystalline structure. As the only place where this pattern can form is within an asteroid or planet with a molten core, the Widmanstätten structure is diagnostic in the identification of an iron meteorite. Different crystalline patterns can develop as a result of varying metal compositions and cooling rates (see lots 10 and 73). Prior to Count Alois von Beckh Widmanstätten having noticed this structure, an English researcher working in Italy, William Thomson, discovered the pattern and wrote a scientific paper about it. Regrettably, Thomson was cut-off from his English-speaking colleagues due to the Napoleonic Wars, and Napoleon’s invasion of Naples caused Thomson to flee. He died shortly thereafter and never received the credit he deserved. This partial slice is etched on both sides. Inclusions of the mineral schreibersite are much in evidence. Schreibersite contains phosphorus and many researchers believe schreibersite — delivered to Earth via asteroid impacts billions of years ago — was a major source of phosphorus which