[meteorite-list] Ghubara as a bleeder

From: Adam Hupe <raremeteorites_at_meteoritecentral.com>
Date: Thu Nov 9 01:07:55 2006
Message-ID: <02d001c703c5$1aa1a3f0$6501a8c0_at_HPDESKTOP>

The important thing with Ghubara is the same for most chondrites. It is all
in how it was prepared. Any known bleeder like Ghubara should be polished to
a lustrous finish regardless of contrast lost. The more polished a surface,
the less surface area available to trap moisture. It is important to polish
both sides of a chondrite slice immediately after it has been cut for this
very reason unless it was cut using mineral oil in which case until it dries
out. Never polish with tap water which starts a reaction in some stones.
Always use distilled water which is cheap and better on the polishing
equipment. Chlorine and other chemicals contained in tap water are
corrosive, especially in contact with metal. It also attacks the rubber
seals and bearings in your cutting and polishing equipment. It is important
to clean a slice immediately after polishing and to heat it up to no more
than 190 degrees Fahrenheit for about an hour. Anything higher than 190
degrees may drive off some of the extraterrestrial gases contained in the
meteorite thus invalidating some future scientific study. If oxidation
appears in the future, dry polish it using emery cloth and wipe it off with
a lint-free towel. I have had to dry polish two or three times with some
real troublesome stones until they equalized with their environment and then
never had a problem again including Ghubara.

Hope this helps,

Adam
Received on Thu 09 Nov 2006 01:05:49 AM PST