> On 3/29/2011 5:06 PM, Alain wrote:

>>>
>>> Is there *any* chance the crystals might actually be calcite?
>>
>> No, calcite's basic formula is CaCO3 (calcium carbonate), while your
>> cristals could be CaCl2 or some other nClx salts.
>>
>
> Oh well :(
>
> I wonder if there's some way to grow calcite crystals using a saturated
> calcium carbonate solution. Acids and bases usually form salts, but
> there's got to be *some* way to do it. Even if it took years to grow a
> small grain, it would be worth it!

In a laboratory, or your kitchen, it should take a mather of hours, 
maybe a few days to grow any mineral crystal.

You start with a warm saturated solution, put in some nucleating bit. It 
can be a grain of sand, a speck of dist, the tip of a needle,...
You sometimes need to slow down the process to get beter quality 
crystals. In that case, you start with a solution at room temperature 
and only rely on evaporation.

As the solution cools down and the solvent evaporate, the crystals grows.

Very simple process.

The problem you usualy face with calcite, it that it's not very soluble. 
This limits the dimention that the crystal can reatch. You can 
circumvent that by refreshing the solution by forcing some circulation. 
You need a source area with a higher carbonic acid content that make the 
calcium carmonate more soluble. Then you need a crystalisation area 
where the carbonic acid evaporate into CO2, reducing the solubility of 
the carbonate and forcing it to crystalise.





Alain

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