Hal remembers correctly that I worked on H and O isotopes
in alunite and jarosite during a post-doc at USGS in 1987-89.

As discussed by Stoffregen and Alpers (1992, Amer. Mineralogist,
v. 77, p. 1092-1098), we found that heating alunite to 400 deg. C will remove
hydronium and other "non-OH" water that is subject to relatively
rapid exchange at low temperature.  Water representative of the OH
sites was then removed by heating at 950 deg. C for one hour.
(For most samples we heated first to 350 and then 400 deg. C.)  The water
removed
at these lower temperature steps had different delta-D, as discussed
in the paper.  We found it useful to use thermogravimetric analysis (TGA)
and differential thermal analysis (DTA) to determine the temperatures
at which alunite and jarosite break down.

Some other references on H and O isotopes and stoichiometry in alunite
and jarosite:

Alpers, C.N., Nordstrom, D.K., and Ball, J.W., 1989, Solubility
of jarosite solid solutions precipitated from acid mine waters,
Iron Mountain, California, U.S.A.: Sciences Geologiques Bulletin,
v. 42, p. 281-298.

Alpers, C.N., Rye, R.O., Nordstrom, D.K., White, L.D., and King, B.-S.,
1992, Chemical, crystallographic, and stable isotopic properties
of alunite and jarosite from acid-hypersaline Australian lakes:
Chemical Geology, v. 96, p. 203-226.

Rye, R.O., and Alpers, C.N., 1996, The stable isotope
geochemistry of jarosite [abstract]:  Geological Soc.
of Amer., Abstracts with Programs, v. 28, no. 7, p.
A150-A151.
(The poster session we gave at the 1996 GSA has been written
up as a USGS Open-File Report that has been approved
by the USGS but is not yet printed in final form.
I'll post a message on ISOGEOCHEM when the Open-File
report is available.)

If you want reprints of these papers, please e-mail
me directly ([log in to unmask]) - do not press "reply"!

Thanks,
Charlie

At 03:01 PM 11/12/97 -0500, you wrote:
>>Dachun,
>>
>Some years ago Charlie Alpers (then a NRC postdoc?) did some work on
>alunite or jarosite "water" if my memory serves me right.  You might look
>for some of his publications.
>
>Hal
>
>P.S.  I am not sure whether you will get representative D/H ratios since
>dehydration will leave one H behind for every two OHs etc....
>
>
>>
>>At 11:22 AM 11/12/1997 -0800, you wrote:
>>>     Dear All: I will be very grateful if somebody can give me suggestions
>>>or references as  how to extract water from alunite,
>>>K2SO4.Al2(SO4)3.4Al(OH)3, for D/H and 18O/16O  analysis. I tried vacuum
>>>distillation at 550 degree C. Instead of pure water, I  got sulfuric acid
>>>with very strong smell of SO2. Best regards. Dachun Zhang Global
>>>Geochemistry Corp. 6919 Eton Ave. Canoga Park, CA 91303
>>Dr. Greg B. Arehart
>>Department of Geological Sciences
>>University of Nevada - Reno
>>Reno, NV  89557-0132  USA
>>ph: 702-784-6470
>>fax: 702-784-1833
>>email: [log in to unmask]
>
>
>Dr. Haraldur R. Karlsson
>Associate Professor of Geosciences
>Deptartment of Geosciences
>Texas Tech University
>Box 41053
>Lubbock, TX 79409, USA
>
>(806)-742-3130 voice
>(806)-742-0100 fax
>