Re: hemihydrate (was: extinction6)

["Richard W. Travsky" <rtravsky@uwyo.edu>]

On Sat, 14 Feb 2004 Tetanurae@aol.com wrote:
> jedimr_thomas@hotmail.com wrote:
> <<I guess not, 'cause anhydrite is greek for "without water", and my 
> Mineralogy-syllabus sais:
> Gipsum: CaSO4.2H2O
> Hemihydrate: CaSO4.1/2H2O
> Anhydrite: CaSO4
> of course this might be wrong nobody's perfect, but it seems logical>>
> 
> According to the Webmineral website, the mineral your professor is refering 
> to is known as Bassanite, 2(CaSO4)·(H2O), which essentially the same formula 
> listed by your instructor:
> 
> http://www.webmineral.com/data/Bassanite.shtml
> 
> There is no entry for Hemihydrate or anything close to that in its spelling.

A google search turns over 9000 hits. It's actually a more general term

 http://www.bartleby.com/61/40/H0144000.html

 NOUN: A hydrate in which the molecular ratio of water molecules to
 anhydrous compound is 1:2.

which makes a little bit more sense of  Hemihydrate: CaSO4.1/2H2O