Craig Martell on sun 11 apr 99
Hi:
Ceramic Grade spodumene from Foote Minerals hasn't been available for at
least 10 years. I don't know what the dude at Mile Hi Ceramics is thinking
about! When Foote's ceramic grade ran out, Chemical Grade spod came on the
market as a replacement and I, for one, didn't like it or want to use it.
If you fire fusion buttons of ceramic and chemical grade spod to cone 10 and
compare them, there's quite a difference. The ceramic is a dry orange
button and the chemical grade is a more fused but very dirty brown. Which
brings me to a thing I harp about every now and then. If you do fusion
buttons of your feldspars and lithium spars and nepheline syenite, you can
compare them every time you buy an new supply and check for any visual
changes in melt, crackle, volume, whatever. When Kingman spar went down the
toilet, it changed from a pearly white glassy button to a dirty grey, less
fused one although the analysis was not changed or updated! Hmmmmm! This
time, the eyeball was one up on the paperwork and calculation.
Ceramic grade spod analysis
SiO2 63.70
Al2O3 26.15
Fe2O3 0.65
K2O 0.60
Na2O 0.32
Li2O 6.88
Chemical Grade spod analysis
SiO2 63.00
Al2O3 24.80
Fe2O3 2.00
K2O 1.18
Na2O 0.60
Li2O 5.70
Craig Martell in Oregon
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