Re: Is coral calcium a hydrophillic or hydrophobic mineral?

Dear Kate

Coral skeleton is made of Calcium Carbonate (CaCO3) that is secreted by the
coral animal itself by using the chemicals present in the surrounding water.  
There are two forms of calcium carbonate; Aragonite and Calcite, both with
similar chemical formula but different crystal shape.  Aragonite is denser of
the two forms.  All corals secrete Aragonite and their skeleton is made up of
the same.

Now, to the question whether coral skeleton is hydrophilic or hydrophobic.....
I believe and in my opinion Coral skeleton is hydrophilic...coral tissue and the
skeleton (Aragonite or calcium carbonate) are in contact with seawater.
I hope this answers your question

Shashank


Admin Note:
Aragonite is indeed hydrophilic,  it will dissolve slightly in water, and the
dissolution characteristics depend somewhat on pH.  There is some concern that
acidification of the ocean (caused by increased CO2, which forms carbonic acid
when dissolved in seawater and thus lowers pH) will have an impact on calcifying
organisms, including corals.  More on that here:
http://www.wbgu.de/wbgu_sn2006_en/wbgu_sn2006_en_voll_4.html

-Rob Campbell, Moderator