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Once again a new mineral has been discovered in a meteorite. The last example was "Wassonite", made up of sulphur and titanium, found in an Antarctic chondrite. The new mineral, called "Krotite" (in honour of Alexander N. Krot), has been found in an inclusion (photo above) in a meteorite found in Africa in 1934.
Announced in the May/June issue of the American Mineralogist journal, the discovery was made by Harold C. Connolly Jr. and Stuart A. Sweeney Smith (City University of New York and the American Museum of Natural History) who first examined the inclusion which they have called "the cracked egg".
Further analysis of the inclusion involved a nano-mineralogical study by Chi Ma (California Institute of Technology) and an X-ray diffraction study by Anthony Kampf (Natural History Museum of Los Angeles County).
From these studies it turns out that Krotite is a refractory (stable at high temperatures) calcium aluminium oxide (CaAl2O4), formed at low pressure. The atomic structure is actually very similar to a component in some types of high temperature concrete. The fact that this material requires temperatures of
at least 1500°C to form helps explain why the inclusion remained intact during its passage through the atmosphere.
The minerals found in meteorites are generally thought to date from the epoch of creation of the solar system, but if the mineral requires very high temperatures and also low pressures to form then this suggests that it formed exceptionally early, when the protoplanetary cloud (low pressure) was first illuminated by the proto-Sun (high temperatures). The Earth was yet to form!
There is therefore every reason to suspect that Krotite is one of the oldest minerals in the solar system, if not the oldest, and that in its physical and chemical properties we can read part of the history of that remote age.
The analysis of the inclusion continues as it also contains several other minerals, one of which also appears to be unknown.
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