Yes...Kieron is right...I have some of the Pultusk fall that has been dug out recently and it still has quite a good fusion crust after all those years in damp ground...Pultusk also has a much higher iron content and has still survived.(I donated some to the OU for weathering tests, comparing the fresh stones recovered at the time to recent finds....there was hardly any change to the O isotopes...eg terrestrialization...I have been metal detecting around Barwell where it was possible to get permission and there is so much slag and iron rubbish around it is almost impossible to progress any distance to search and on top of that the low iron in Barwell makes it almost impossible to detect more than a couple of inches down in the soil....I have done tests burying similar NWA's.
Hope to see some of you tomorrow at the Barwell event...just finishing off packing up space rocks to take along.
Graham