Many of the meteorites found in desert environments have been subjected to "sand blasting" for many years. This can alter the fusion crust to different degrees depending on time and conditions. I've seen many meteorites from the NWA region that have had most if not all of the fusion crust removed by the erosive effects of wind and sand. Others have just been polished by this effect and still have some fusion crust remaining even though the surface may be shiny as you mentioned.
Desert varnish can also make it hard to make an accurate determination about the amount of remaining fusion crust. The only way I know of is to cut a window that is at or near a right angle to an uncut surface of the meteorite. A close look under magnification will show whether or not there is any fusion crust there.
Best,
John Gwilliam
At 10:42 AM 12/10/03 -0500, [EMAIL PROTECTED] wrote:
When I look at some of photos of the hot desert NWA meteorite Ebay auctions, I can't tell if the nice looking blackish brown coating on the individual meteorites is fusion crust or just desert varnish with probably little or no fusion crust remaining. Advice please on helping this novice collector determine the difference. Shiny appearance = desert varnish?
thanks,
jd cowsar
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