Author Topic: Spinel standards  (Read 6757 times)

JohnF

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Spinel standards
« on: January 02, 2015, 03:30:27 PM »
I am looking for a spinel (MgAl2O4) epma standard. Anyone have something to share?

Probeman

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Re: Spinel standards
« Reply #1 on: January 02, 2015, 04:24:19 PM »
I am looking for a spinel (MgAl2O4) epma standard. Anyone have something to share?

Hi John,
I have a lot of this wollastonite:

http://probesoftware.com/smf/index.php?topic=222.msg997#msg997

Good for major silicon and aluminum.
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JohnF

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Re: Spinel standards
« Reply #2 on: January 04, 2015, 03:25:09 PM »
I think you meant Si and Ca (no Al in wollastonite, CaSiO3)

John Donovan

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Re: Spinel standards
« Reply #3 on: January 04, 2015, 03:46:50 PM »
I think you meant Si and Ca (no Al in wollastonite, CaSiO3)

Yes, sorry. I ain't no darn geologist!

But that does remind me: I'd love to find a super pure end member aluminum silicate, such as sillimanite.
« Last Edit: January 04, 2015, 04:33:37 PM by John Donovan »
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Gseward

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Re: Spinel standards
« Reply #4 on: March 04, 2015, 11:32:55 PM »
JohnF and I discussed this off-line. We discovered this:

http://www.mtixtl.com/mgal2o4spinel.aspx

Jeremy Wykes

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Re: Spinel standards
« Reply #5 on: March 04, 2015, 11:59:10 PM »
A heads up on synthetic Mg-Al spinel: If I remember correctly, Hugh O'Neill suggests that synthetic MgAl2O4 he has examined in the past has considerable non-stoichiometry.
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Gseward

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Re: Spinel standards
« Reply #6 on: March 05, 2015, 12:46:27 PM »
Thanks for the warning. I guess heterogeneity is worse!

Probeman

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Re: Spinel standards
« Reply #7 on: March 05, 2015, 01:41:31 PM »
A heads up on synthetic Mg-Al spinel: If I remember correctly, Hugh O'Neill suggests that synthetic MgAl2O4 he has examined in the past has considerable non-stoichiometry.

Would that be true even for single crystal material?  I believe Sean Mulcahy (UB Berkekey) has single crystal Mg-Al spinel from when I bought it years ago.  Worth testing I guess.
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AndrewLocock

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Re: Spinel standards
« Reply #8 on: March 25, 2015, 04:25:38 PM »
We purchased a large polished single-crystal wafer (substrate for crystal growth) of MgAl2O4 spinel from MTI some time ago. My recollection is that examined the cell dimension by powder XRD of an aliquot, and found it to be in excellent agreement with ideal MgAl2O4. From this, we assumed the composition was stoichiometric.