[Stoves] large camp stoves

[Kevin Chisholm]

Dear Mary

Granite is an igneous rock, so it will not inherently decompose with 
heat, as would limestone or dolomite, or any hydrated mineral. So far, 
so good...

Granite is a mixture of mica, feldspar, and silica, among other things. 
The problem is that quartz (Si02, Silica) has peculiar expansion 
properties. It exists in three crystal forms... quartz, tridymite and 
cristobalite, and there is a very large expansion over a narrow 
temperature range, as the SiO2 changes from one crystal form to another.

The answer to your basic question "Can I use the granite blocks to build 
a stove?" is "Yes and no."

YES, you can use it, if you don't heat it too quickly, or to too high a 
temperature. NO, you cannot, if you heat it too hot, or too fast.

See: > http://www.a-m.de/englisch/lexikon/quarz.htm

This suggests that if you stay below about 500C you should be OK.

If I was you, I would take a piece of the proposed granite over to a 
friend that had a pottery kiln, and place it in the kiln to see what 
happened. :-)

Best wishes,

Kevin




MARY BARBER wrote:
> Has anyone tried using granite blocks rather than bricks in building large stoves?
>   We have an abundance of them here and I thought they might last longer than the bricks which are often not too hard. Or would they soak up too much of the heat?
>   Many thanks for all your comments
>   Mary
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