Dear isogeochemers,

I am about to separate kfs-OVERGROWTH from Cambrian and Ordovician samples
from the Appalachian Basin for isotopic analyses  ...  and I have some
questions:

1.       For heavy liquid separation from the other minerals,  mainly qtz
and plag,  I'd like to have the appropriate density beads to make up and
control the heavy liquids.  Our old set of density beads in incomplete,
and we cannot find any address of any supplier or so.  We have searched in
all catalogues and the net.  Our old set is from "Rayners",  made in Great
Britain.  Does anybody know of any supplier of density beads ?  Or do you
have any of them sitting around in your lab and you don't need them any
more ???  We need beads between 2.2 and 3.0.

2.      I've been reading about the general mineral separation procedures,
and the overgrowth techniques in particular,  -  some people use the sodium
pyrosulfate fusion to get rid of all moneral BUT qtz and fsp,  wheras some
others don't.  However,  I cannot find any quote or reference about the
temperature at which this fusion should take place.  I read/was told
different things:
(a)     that I have to go to temp. of > 800 deg C,  because only then SO3
forms from the reagent,  and the SO3 then can react withm  and destroy
minerals such as mica;
(b)     that temps of around 300 deg C are sufficient,  i.e. high enough to
make the salt crystals melt;
(c)     that I shouldn't even think of thinking about using this thechnique
if I'm after the kfs-overgrowth;
Some say to never use temperatures higher than 50 deg C during the whole
procedure of separation,  in order to not affect the del18O value of the
kfs  -  whereas others go to temperatures of several hundreds of deg C.
And I also was told that temps up to 300 deg C would not affect the del18O
value of ksf,  ...

....  so -  I'm confused,  and I'd like to ask for your help.   Any advise,
comments, experiences,  ideas,  references, etc. pp. ...  are VERY
WELCOME!!!!!!


THANKs very much,

Karen

***********************************************************************
Dr. Karen Ziegler                        tel/main office: (++)519-661-3187
Lab. for Stable Isotope Studies  tel/lab: (++)519-661-3881
Dept. of Earth Sciences               fax: (++)519-661-3198
University of Western Ontario   e-mail: [log in to unmask]
LONDON,  Ontario
Canada N6A 5B7

Home: 415-251 Platts Lane
LONDON,  Ontario
Canada N6H 4P4
tel: (++)519-673-5322