Howdy All-
        In the interest of creating my everyday working carbonate standard,
I've ground hand samples from a local limestone to a fine powder .  I guess
geomorphologists would call the resulting texture rock flour.  I figured the
finer the grind, the easier it would be to achieve homogeneity.  It has
since been pointed out to me that too fine a grind might lead to a poor
standard (we haven't had a chance to start analyzing it yet).  Friedman and
O'Neil (1977) make mention on page KK5 that the Solenhofen LS (NBS-20) is
"too fine grained to be a good and lasting standard."  Does this have to do
with potential contamination of atmospheric vapor, difficulties in handling
the standard, or other factors?  Can anyone suggest a suitable "grain size?"
If my lab RH is about 17%, and I store the standard in a dessicator, do I
even need to worry (excessively) about potential atmospheric vapor?  Thanks
in advance for any insights.   Best Regards-  Mark


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  R. Mark Larson
  Research Scientist
  UWYO Stable Isotope Facility
  Dept. of Renewable Resources
  University of Wyoming
  Laramie, WY 82071-3354

  Email:     [log in to unmask]
  Phone:     307.766.5203
  Fax:          307.766.6403