[Rockhounds] Terlingua-type calcite

[Axel Emmermann]

Hi Don & list

Last time the subject came up I wrote: 

> I'd have to look up the exact page (it's somewhere around p. 
> 200) but I think that my Marfunin says somewhere that 
> DIVALENT REE don't feel the crystal field effect much whereas 
> higher valences of REE do. -----
-----I 'm trying to get myself to re-read the 
> entire "Spectroscopy, Luminescence and Radiation Centers in 
> Minerals" by Arnold Marfunin. I didn't quite get the full 
> concept the first time around ;-))) So I thought that my 
> vague ramblings might better be interpreted and revised by 
> some bright new professional ;-)))
> 
> Any sense to be found in this???


Well, it's not Marfunin.
I found the text-"snippet" and it IS the other way around. 
Divalent REE feel the crystal field effect much more than the trivalent ones
(generally speaking, there's all sorts of "but" and "or" and such... ). It
makes sense, in a reverse way... 
The text refers to the "daylight" colors of minerals but that has to count
for fluorescence too.
I knew I read something about it somewhere and I assumed that it was Arnold
Marfunin 's "Spectroscopy, Luminescence and Radiation Centers in Minerals"
because it struck me as something to remember.
The full text can be found in: 
"Farbe und Lumineszenz von Mineralien" by Gabriele Steffen, chapter 3:
Farben durch Kristallfeld-Effekte, pages 56-57. ISBN: 3-13-118341-1
2000 ENKE im Georg Thieme Verlag
Stuttgart - New York.

I just thought I needed to get it set right ;-)))

Cheers
Axel