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Meteorite Preservation Dome:
Displaying meteorites in a dry environment

Collecting meteorites comes with the responsibility of having to protect them against often harmful environmental conditions on planet earth. Most meteorites just don't like moisture. Especially when living in a wet climate environment, this can result in having to store fresh meteorites away, out of sight, in airtight containers containing desiccant. As a collector who lives in a wet climate, I found myself in such a situation.
To be able to enjoy seeing at least some of my meteorites without having to retrieve them from storage first, and without exposing them to moisture, I worked out the concept described below. It makes use of a glass dome, a specially made aluminium base, silica gel desiccant impregnated with a blue indicator that turns pink when moist, a glass disk (coaster) and white Vaseline. All ingredients for the concept, except the aluminium base were bought as is. The base was specially designed and machined for the display.

The glass dome originally came with a wooden base. I first tried to create a dry compartment using this wooden base. To seal the interface between base and glass dome, I first considered oil, but discarded this idea as too messy. Adhesive or silicone sealant would be too permanent. Finally I decided to try white Vaseline.
A little dish with silica gel was put underneath the Vaseline-sealed dome... It did not work. The wood turned out to be too permeable for water. The silica gel absorbed water from the wood so fast, that it turned pink in only a day.
For a next test of the concept, I used the same configuration, but this time with aluminium foil covering the wooden base. One sheet of foil covered the flat central base, and followed the internal contour of the groove. Although not looking very presentable, it worked! The blue silica gel stayed blue for six months.
Time for the next step...
Based on the first experiments, I decided to design a base, to be machined out of a solid block of aluminium.
Next to a groove to hold the white Vaseline and to insert the glass dome in, the base should have a cavity to hold the silica gel. The blue silica gel - impregnated with dehydrated cobalt chloride as a moisture indicator - should not be able to contact a meteorite. Air should be able to pass freely though. It should be possible to check the colour of the silica gel without having to open the display. Furthermore I wanted a meteorite to rest on glass, so I wouldn't have to worry about galvanic corrosion.
The result can be seen in the sketch to the left.

To open a PDF file containing a drawing including measurements, click the sketch to the right.
To fill the groove with white Vaseline in such a way that it completely closed the gap between glass and aluminium, I made use of the low melting point of white Vaseline. It melts at a temperature well below the temperature of boiling water.
A safe way to melt the Vaseline is by floating a little bowl containing Vaseline in boiling hot water.
(Note: Using an oven to melt the white Vaseline can be dangerous, as Vaseline fumes are flammable!)
To support the flow of molten Vaseline in the groove, and to obtain sufficient time to place the dome, the aluminium base was pre-heated in hot water (and dried afterwards). The heat capacity of the aluminium base was more than sufficient, to be able to fill the groove and put the dome in place before the Vaseline started to solidify.
To the left, the final result is shown. I'm curious how long the silica gel with stay blue, indicating a safe environment for the fresh stony meteorite inside.
The test with the aluminium foil covered wooden base worked well for six months, after which I ended the test. The final configuration didn't show any change in colour of the silica gel since being closed two months ago (September 2011).

Note: I designed the cavity in the base to be large enough, to contain sufficient silicagel, to dry the air inside the dome. It will not hold sufficient desiccant to dry any unconditioned meteorite also. Therefor the meteorite should be dried - in for instance an air tight box with desiccant - before being put in the dome.
I have been thinking about some possible improvements. White milk glass could be used instead of the clear glass as a base plate for the stone. A stand could be added inside of the dome, to lift the meteorite. The challenge would be to make it stable though. Also a lower dome might improve the display.
In case you might want to give it a try yourself, please feel free to copy and improve the design as desired.
I would appreciate hearing about your experiences!: info@AsteroidChippings.com

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