February 2, 1934
Dear Professors Noyes and Buwalda:
In the years 1927-32 I was very much interested in the structure of the crystals of
the silicates and related materials, and devoted much effort to the study of this
subject. This work was brought at that time in some degree to its conclusion by the
wide application of a set of structural principles for complex ionic crystals. Since
then I have been attacking the problem of the sulfide minerals, with the hope of ultimately
reaching a similar understanding of the general principles determining their structure,
composition, and properties. This program has progressed slowly; my students and
I have determined the structure of chalcopyrite, sulvanite, binnite, enargite, tetradymite,
and stannite. However, the investigation of more complex crystals and of minerals
which do not crystallize well requires some apparatus which we do not possess, and
involves extensive and laborious graphical and numerical calculations. May I request
you to communicate to the Geological Society of America an application for a grant
of money to permit the intensive prosecution of this investigation during the next
year?
The grant desired, of the sum of twenty-five hundred dollars, would be expended in
following way. About one-half would be used for the construction of x-ray apparatus,
consisting of a Weissenberg or Sauter x-ray goniometer attachment to the rotating
crystal apparatus, and an accurate powder apparatus, including a metal x-ray tube
with replaceable anticathode. The remaining one-half would be used as stipend for
the employment of one full-time or two half-time research assistants, to carry out
the laborious graphical and numerical work involved in the reduction of the data and
to assist with the experimental work.
With this aid, I would plan to carry out during the year ending June 30, 1935, the
complete structure determination of pyrargyrite, proustite, pentlandite, and covellite,
and of the minerals of the niccolite group (niccolite, pyrrholite, breithauptite,
etc.). Preliminary x-ray studies have been made on all of these minerals, which indicate
that their careful investigation should provide especially valuable information regarding
the general nature of the sulfide structures; and I believe that the completeion of
this program would do much to bring the same clarity into the field of sulfide minerals
as has been reached for the silicates.
I should be glad to prepare a more detailed formal application if desired.
Very truly yours,
Linus Pauling
Professor A.A. Noyes
Professor J.P. Buwalda
California Institute
