[meteorite-list] Water in space

[MexicoDoug at aol.com]

Tracy L. wrote:
>Exactly!  Consider the case of copper  carbonate.  In its hydrated form, 
>it is a pretty blue crystal; we  used to use it in our swimming hole in 
>low amounts to kill off algae and  weeds.  In its anhydrous form, it's 
>a greenish powder.  Don't  eat either one; bad.   I'm not akamai enough
>to guess what  hydrates might be present in meteorites, but I'm pretty 
>sure this is  what is meant by water being present in meteorites, 
>chemically bound  into various minerals, which may be released by 
>heating or chemical  reaction.

A-Hola Tracy, Hmmmm.  The idea that a hydrate is a great  way to stabilize 
water I totally agree with you and the physics of it, so I  follow there.  But:
 
I think you are confusing copper sulfate (pretty hue, light royal blue  
crystals) with copper carbonate and/or copper carbonate hydroxide  minerals.  
Copper carbonate does not form a hydrated complex in a chemical  sense, though 
copper carbonate hydroxide might be loosely called "hydrated"  instead of a 
hydroxide, by some fast talking pool chemical salesman (or mystic  jewelry peddler?) 
at local pool store if it is really sold there (?).   Anyway, a hydroxide is 
a different chemical animal than a hydrated complex  containing water which is 
bound by weaker structural or van der waals types of  attraction: that to 
which I think Chris eluded and of main interest here for  water are 
chemical/structural "hydrates".  

That chemical hydrated  compound on your mind would likely be Copper Sulfate, 
wouldn't it?  It  forms a pentahydrate = complex with 5 water molecules per 
Copper/Sulfur.   The Copper carbonate might be an undesirable precipitate in 
the swimming hole  produced from interaction of copper sulfate with lime or 
disolved carbon dioxide  I bet, and it might be a yucky green?

Copper Sulfate (a.k.a., synthetic  chalcanthite) is a beautiful lab example 
of a stable hydrated complex to at  least +150 C.  It is quite possible it 
could appear in trace quantities in  meteorites, so you are not far off at all if 
we deal with CuSo4*5H20 !!   

However, the more common hydrated (i.e., bound water) reservoirs found  in 
some meteorites I found in the literature based on your contemplation of not  
even guessing, would be a suite of clay minerals, which can result from the  
aqueous modification ("weathering") products of feldspars and pyroxenes, common  
meteoritic stock.  That is the same kinds of clay that expands when you mix  
it with water and can be formed into shapes...i.e., hydrated clay - well not 
all  Clays hydrate, but plenty do.

Clay minerals are very complicated beasts  that still cause all kinds of 
trouble even regarding nomenclature to say what is  what, since their structures 
vary so much, simply being a woven backbone pattern  of silicates and 
hydroxides and a variety of candidate cations/metals, and  ambiguous formulae something 
like (Ca,Na,H)(Al,Mg,Fe,Zn)2(Si,Al)4O10(OH)2*n(H2O)  in the case of 
smectites, which can form widely variable laminar sheets which  suck up water between 
them better than silica gel!  Unlike copper sulfate,  slight changes in 
temperature and humidity can reverberate by changing their  structures, formula, and 
most importantly, amount of bound water - even getting  a density is hard, let 
alone a positive compositional ID.  So that is why  you can't do too much 
better than "clay minerals".  The two best tests are  a taste test and messy 
Separation-Xray analysis.  And that would seem to be  the variable/flexible nature 
of much of the bound water in  not-too-shocked-and-baked meteoroids for s/he 
who wants to really do some  bonding with them...

For chondrites, here are some of those hydrated  beasts that serve as space 
oasises (that has a nice ring to it):

Type 3:  phyllosilicates, principally smectites and micas, serpentine 
associated with  ferrihydrite.
Type 2: Smectites (rare in the CM2s, abundant in the CR2s),  Abundant 
serpentines (with extremely variable compositions and structures),  Mg-Fe sulfates, 
tochilinite-serpentine intergrowths and carbonates.
Type 1:  Saponite + (Serpentine) 

Taken from an impressive face-off of Zolensky  and Bischoff in Maui at:
WORKSHOP ON PARENT-BODY AND NEBULAR MODIFICATION OF  CHONDRITIC MATERIALS 
(preliminary program)
June 17, 1997, Maui,  Hawai'i
http://www.lpi.usra.edu/meetings/chondrite/pdf/program.pdf

I  chose the Zolensky writeup not because I don't believe the other competing 
 theories (I am a Bischoff fan), but rather because of the enumeration of  
minerals he did including some clay and other hydrate-ables.  The  documentation 
is:
AQUEOUS ALTERATION OF CARBONACEOUS CHONDRITES: EVIDENCE FOR  ASTEROIDAL
ALTERATION. M. E. Zolensky, Mail Code SN2, NASA Johnson Space  Center, 
Houston TX 77058, USA.

Wish to have been a fly for three days on  the hotel wall in Maui then,
Aloha, Doug