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Meteorite deterioration & weights.

Hi everyone,

While we're on the topic of deterioration and preservation of meteorites, I
thought you might be interested to hear this.

I've purchased etched iron end-pieces in the the past which have not been
properly prepared before sale. After a few days, I've found actual water
*droplets* appearing from cracks in the crystal boundaries and a great deal of
water coming through the crust. This must be remnants of the coolant used
during cutting and would indicate that some suppliers aren't drying these
pieces properly before offering for sale.
I've had this problem appear several times and from more than one dealer.
Thorough drying should be a standard part of the cutting process in my
opinion, because many of us would take our new purchase and either lacquer it
or oil it as soon as it arrives, thus trapping all that moisture inside!

Another point that springs to my cynical mind, particularly with specimens
being offered in milligram weights recently, is the calibration of dealer's
weighing machines.
I've been surprised to find that slices that I've purchased as perhaps 23.7g,
actually turn out to be 23.2g or 24.3g.
I have 2 digital scales that I use for work....I have to get these checked and
calibrated every 6 months as part of the British Standard approvals, with full
traceability back to a known standard at the National Physics Laboratory.
Can dealers assure us that they also have accurate means to weight specimens
offered for sale and a re-calibration frequency for the measuring instrument?
Regular calibration is not particularly a means to gain a perfectly accurate
measuring instrument, it's more a means of knowing the IN-accuracies and
errors across certain measuring scales. Electronic instruments certainly need
regular calibration, mechanical balances may stand a longer calibration
interval, but even these are not immune.
I must admit that most of the pieces I've purchased and re-weighed myself are
often over the stated weight, but I've certainly had a few pieces that were
under weight....sometimes by quite a lot! If the stated gram weight is
advertised to 1, 2 or even 3 decimal places, it's maybe time to ensure you can
actually meet that kind of precision weighing.

This isn't intended as a criticism, but as shops and stores selling anything
from sweets to potatoes have to undergo regular weights and measures checks,
I'm merely asking the question so that we can all rest assured.


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