[meteorite-list] Dronino Preservation

[Bob King]

Hello Bernd, Marcin and all,

I, too have had problems with Dronino until I used Steve Schoner's 
NaOH method. I left my slice in solution in a jar for two weeks. Every so 
often I'd pick up the jar and swirl the contents around to keep the 
chemicals mixed and monitor the process . The solution gradually 
became as dark as maple syrup as rust was dissolved. Then I removed 
the slice, washed it in distilled water (the lye makes the pieces very 
slippery.) and  baked it in the oven for an hour at around 200 degrees. 
I still keep my Dronino with dessicant but I have not seen a speck of 
rust since this treatment.
Marcin, you asked about dissolving the lye. I fill the jar halfway with 
regular isopropyl alcohol (off-the-shelf drugstore variety) which contains 
water. Then I add about 5 tablespoons of lye (Red Devil brand here in 
the U.S.) and stir and stir. It takes a while for the lye to dissolve in the 
alcohol. While this is happening you get an interesting exothermic 
chemical reaction and the jar warms up.
Anyway, this is the only thing that's worked for really stubborn irons.
Best to all,
Bob


Subject: [meteorite-list] Dronino Preservation

> Stefan wrote:
> 
> "Just watching the slow disintegration of my little 63g Dronino individual.
>  Not the prettiest way of losing weight...Any chance of preserving it from
>  total crumbleation?"
> 
> Matteo responded:
> 
> "Dronino its a horrible rust meteorite, for the moment the 2th only after
> Campo del Cielo."
> 
> Don't forget Nantan...another rust bucket. I had a nice Nantan individual
> that I purchased at a mineral show in Ulm (Germany) in 1999. About two
> years later it had rusted and crumbled almost beyond recognition.
> 
> Morasko can also be very, very prone to rusting. My little piece from ...
> looks jet-black as if HCL had been poured over a lump of sugar :-(
> 
> Luckily I was careful enough because I bought only a small 12-gram endcut
> which I observed rusting away in spite of the silica gel I used to protect it.
> 
> Dronino is a very difficult candidate because of its large amount of sulfides
> (about 10vol%!). Moreover, its sulfide nodules are usually surrounded by Fe
> hydroxides, ... a fateful combination with regard to hard-to-stop rusting :-(
> 
> Cheers,
> 
> Bernd
> 
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