Kakanui hornblende

[Malcolm Roberts]

Folks.....
I am wrestling with a user who demands perfection and believes in absolute values. I have been using kak hornblende as a secondary standard for some purposes on and off for a while and quickly picked up some element of variability. I have compiled some data and am gradually gathering more. Would anyone be carrying out similar antics or have information on what they consider as an acceptable composition plus error.....?
Cheers,
malc.

[John Donovan]

Hi Malcolm,
Here is an abstract that Ed Vicenzi (user forum name is qEd) that describes some of the issues.

http://www.geology.wisc.edu/courses/g777/MM/Vicenzi-Rose-Kak-2008.pdf

He also presented this is an extended presentation at the MRS meeting in Denver a few years ago. You might ask him for a pdf of the PPT.

[JohnF]

Henny Cathey and I were running some low kV FE epma experiences recently at ASU (we'll be presenting this at the December 2014 AGU meeting in San Francisco). In preparation to run sub-micron domains on tiny "sieve amphiboles" [actually may not be amphiboles] in pseudotachylite, we spent over a day calibrating on various standards. Particularly the Kakanui hornblende as we assumed our target phase would be amphibole. One of the arguments for getting a field emission probe is that you can now see so much better what you are probing. Boy, is this the truth. The Kakanui is chock-full of micron to sub-micron 2 or 3 phase inclusions: apparently an Fe-oxide, a silica-rich phase (glass I am guessing) and possibly a vapor bubble (or the hole left by it). See attached image. Which led to a literature search describing its field occurrence...presumbly these are remanent melt inclusions of this volcanic phase, which also base evidence of re-heating. So, yes, it is no surprise that it exhibits some degree of heterogeneity.

[Probeman]

Henny Cathey and I were running some low kV FE epma experiences recently at ASU (we'll be presenting this at the December 2014 AGU meeting in San Francisco). In preparation to run sub-micron domains on tiny "sieve amphiboles" [actually may not be amphiboles] in pseudotachylite, we spent over a day calibrating on various standards. Particularly the Kakanui hornblende as we assumed our target phase would be amphibole. One of the arguments for getting a field emission probe is that you can now see so much better what you are probing. Boy, is this the truth. The Kakanui is chock-full of micron to sub-micron 2 or 3 phase inclusions: apparently an Fe-oxide, a silica-rich phase (glass I am guessing) and possibly a vapor bubble (or the hole left by it). See attached image. Which led to a literature search describing its field occurrence...presumbly these are remanent melt inclusions of this volcanic phase, which also base evidence of re-heating. So, yes, it is no surprise that it exhibits some degree of heterogeneity.

What Ed Vicenzi and John Fournelle are discussing above is what Paul Carpenter coined "ugly" as in "The Good, the Bad, and the Ugly" standards. 

A more scientific classification system for standards should be implemented.  Maybe this is something that can be discussed in Julien's standards FIG at the EPMA 2016 TC in Madison in May?
john