[meteorite-list] question on performing a nickel test

From: Randy Korotev <korotev_at_meteoritecentral.com>
Date: Sat, 20 Dec 2008 13:19:02 -0600
Message-ID: <200812201917.mBKJHjh09062_at_levee.wustl.edu>

Mike:

I've had the same experience. The problem, I think, is that the DMG
test is actually TOO sensitive to nickel. All meteoritic metal
is >5% (50,000 ppm) Ni. Metals with only a few hundred ppm Ni will
give a positive result with DMG test, however. I think many steels
and cast irons may have a few hundred ppm Ni.

This subject came up a few years ago on this list and someone (I
forget who) mentioned that in his experience, the swab stayed pink
quite a bit longer with a real meteorite metal while the pink faded
in an hour with "false positives."

Randy Korotev







At 14:09 19-12-08 Friday, you wrote:
>Hi List,
>
>If someone has experience with the Allerderm Nickel test and wouldn't
>mind sharing their knowledge of how to do it...
>
>I am attempting to do a nickel test at home here and I ran into a bit
>of a snag. I have a piece of iron that most likely is not a piece of
>meteoritic iron that I was using as a test piece. I sanded a surface
>on it, cleaned it with alcohol several times, got out the trusty
>Allertest NI test kit from Allerderm, placed a drop each of the
>little bottles onto a cotton swab, and placed that on the cleaned
>surface of the metal. Using this piece of iron as a control piece, I
>wanted to be sure I wasn't doing something in the steps I was using
>that would cause me to get a false positive. On this test - test,
>the swab turned pink quickly. If I do the exact steps only add in
>placing a drop of white vinegar on the cleaned surface, wait a couple
>minutes and then apply the nickel test, I get almost a blood red swab
>in just the first second. The first time I did this test and saw
>this, I thought I had contaminated the surface so I sanded it again
>down to a fresh surface, cleaned it several times again with alcohol
>before attempting the nickel test without vinegar. Second time, same
>result. When using a drop of vinegar again, same result - blood red
>quickly.
>
>What am I doing wrong, if anything? Could I still have contamination
>on the metal that the sanding and cleaning with alcohol is not removing?
>
>Mike in CO
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Received on Sat 20 Dec 2008 02:19:02 PM PST