Stuart Altmann on mon 6 may 96
At Tom Buck's request, I am sending the composition of "Cornish Stone,"
faxed to me by Mammill & Gillespie on 4/30/96. The analysis itself is not
dated.
"
Cornish Stone
Typical Chemical Analysis:
SiO2 73.0
TiO2 0.07
Al2O3 16.0
Fe2O3 0.14
CaO 2.0
Na2O 3.7
L.O.I. 1.5
"This material is ground to a fineness of 68% - 74% less than 14 microns and
is sieved thourgh a B.S. 120 mesh sieve prior to drying."
No analysis of flourine is given. That doesn't mean that there isn't any,
only that they didn't test for it.
Patty Rehn on thu 9 may 96
I may have missed the original message on this but fluorine goes up to about
1.5% wt. in the granite. The "cornish stone" is probably somewhat lower in F
since it is an altered (by hot water) portion of the original granite. Part
of potassium feldspar is turned to kaolinite and some of the fluorine is
dissolved away. The fluorine was originally carried in the mica. The
cornwall granites are geologically special and have created tin deposits.
The tin occurs as tiny veinlets of SnO2 in the granite. Similar rocks occur
in southern Utah and sourthern NewMexico.
Patty, in cetral Oregon where we are still having hard frosts every night
At 08:14 AM 5/6/96 EDT, you wrote:
>----------------------------Original message----------------------------
>At Tom Buck's request, I am sending the composition of "Cornish Stone,"
>faxed to me by Mammill & Gillespie on 4/30/96. The analysis itself is not
>dated.
>
> "
>Cornish Stone
>
>Typical Chemical Analysis:
> SiO2 73.0
> TiO2 0.07
> Al2O3 16.0
> Fe2O3 0.14
> CaO 2.0
> Na2O 3.7
> L.O.I. 1.5
>
>"This material is ground to a fineness of 68% - 74% less than 14 microns and
>is sieved thourgh a B.S. 120 mesh sieve prior to drying."
>
>No analysis of flourine is given. That doesn't mean that there isn't any,
>only that they didn't test for it.
>
>
David Hewitt on sat 11 may 96
The recent postings on this subject have given the analysis as Faxed
from G. & M. as follows:-
73.0 SiO2
0.07 TiO2
16.0 Al2O3
0.14 Fe2O3
3.7 Na2O
2.0 CaO
1.5 LOi
As so often with an analysis, this does not add up to 100. In this case
it is 96.41, so there is an unidentified 3.34% missing. I expect we all
carefully enter such data into our calculations, to two decimal places
at least, even though we appreciate that we haven't been given the total
analysis and the missing amount is as significant in quantity as many of
the oxides which we are entering.
I don't know that there is much that we can do about it, but does anyone
else worry about?
David Hewitt
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