My Response Jan 27, 2010 Subject: Re: [meteorite-list] Regmaglypts
Jason and All, 1. My reference to “bubbles” is to morphology, NOT voids. Another meteoritic example of “bubble morphology effects” is pallasitic olivines such as Springwater and Imilac. A thought experiment: Once again, envision a melt mass of olivine and nickel-iron solidifying under microgravity conditions – surface energy dominates gravity. On cooling, olivine begins to solidify before nickel-iron. However, since olivine and iron-nickel share a range of temperatures where both are still at least partially liquid (mushy stage), as cooling continues, still-plastic olivines can be surrounded by and sometimes infiltrated and pushed apart by liquid nickel-iron. Cut and polished sections of Springwater and Imilac reveal this as a relatively complex process. Observe 120 angles between some olivines, evidence of a system governed by surface energy. Some olivine boundaries are straight (interior polyhedral shapes); some are circular (a sphere minimizes surface area to volume ratio); some straight and curved (perhaps on the outer surface of the olivine mass). See my "Stepping Back in Time" article in Meteorite magazine Nov. 2003, Vol. 9 No. 4, pp. 21-22 or see it in the publications list on my website at http://meteormetals.com 2. There is NO WAY that the thermal history of a metal can be calculated in reverse, despite hundreds of papers in the meteoritics literature since the original paper of Osmond and Cartaud in 1904 and the more recent, detailed papers on “metallographic cooling rates!” That is more than 100 years of circular reasoning! Industrial metallurgists would be a lot happier if this backward calculation were possible. It is NOT! 3. Speaking of industrial metallurgists, do another experiment: show a cut section of any nickel-iron or stony iron meteorite to a modern INDUSTRIAL metallurgist. Ask him or her to describe the microstructure, without you giving them any “meteorite words” or concepts. Then, Listen! Next, give that person one of the metallic meteorite papers in the meteoritics literature (other than mine) and see if that person can even understand the language and concepts. Meteoritics metallurgy has sealed itself inside an old language, not accessible to today’s busy, industrial metallurgists. To quote one of my industrial metallurgist friends who is a casting expert and who has become a meteorite collector, "meteorite metallurgy is in the Stone Age." We need a NEW METALLURGY for meteorites! Imagine what we could learn! Phyllis Budka http://meteormetals.com/ ______________________________________________ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list [email protected] http://six.pairlist.net/mailman/listinfo/meteorite-list
