In Search of syn MnTiO3 or Tephroite

[Dave C]

Does anyone out there have either a synthetic MnTiO3 or Tephroite that they are willing to trade? If there is anything needed in return let me know... we do have a decent collection of synthetic substrates.

[John Donovan]

Does anyone out there have either a synthetic MnTiO3 or Tephroite that they are willing to trade? If there is anything needed in return let me know... we do have a decent collection of synthetic substrates.

Hi Dave,
I'm assuming you are looking for a Mn standard?

Story time... when I started in microanalysis at UC Berkeley, I was fortunate enough to spend a day or two writing some 100 letters to authors of articles describing synthetic minerals which I had found in back issues of the American Mineralogist (back in the day when a piece of paper, a letter and a stamp were required to communicate long distance).

But the good news is that I got an amazing response from all over the world. One of the best surprises I got was a half dozen transition metal oxide crystals from the Purdue Crystal Lab.  Including Cr2O3, MnO, CoO, NiO, ZnO and SnO2.  I still have those grains in some of my standard mounts and they are really nice because of their stoichiometry and purity. Perfect for use as MAN and interference standards.  The last time I contacted the lab at Purdue I was informed by someone new that I could get more material at $1000 per gram.  Maybe things have changed by now, I don't know.

But in the meantime you might want to check the Open Letter To the Microanalysis Community letter signed by 99 of our colleagues, but particularly the pdf of the "Action Plan" which in the appendix details many sources for various materials that we were able to put together, including George Rossman's private collection:

https://probesoftware.com/smf/index.php?topic=1415.msg10929#msg10929

The "Action Plan" is an attachment to the post linked above, so you'll need to login to see it.

I know that Will Nachlas, Aurelien Moy and John Fournelle are working with several commercial crystal growers trying to obtain several grams of material of various synthetic minerals for initial characterization. The idea being that if a commercial (or national lab) source for various synthetic minerals is discovered that is of high enough purity and excellent stoichiometry, we will purchase a few hundred grams for eventual global distribution in a so called "consensus" standard mount where we have two (or more) materials for each element of geological interest.  That we we can compare k-ratios between labs to determine inter-laboratory consensus.  Maybe then we will truly have a global scientific basis for microanalysis...

The first post in that topic lays out the issues well enough I think:

https://probesoftware.com/smf/index.php?topic=1415.0

[Dave C]

Hi John
 
Yes it would be for use as a standard.  I will follow up with the Purdue folks to see if the MnO is still an option
 
We have found MnTiO3 to work well although the piece we have has fine lamellae that are not stoichiometric but so as long as those are avoided .. no problems. I have looked at a number of natural tephroites in our collection but non of them turned out to be reasonably homogeneous.
 
Anyway, for those interested we have a decent inventory of synthetics including TiO2, CaTiO3, Cr2O3, NiO, CoO, ZnO, Y2O3 plus a good number of MTI substrates if any one out in probe-land is looking to trade.
 
Cheers
 
Dave

[John Donovan]

Anyway, for those interested we have a decent inventory of synthetics including TiO2, CaTiO3, Cr2O3, NiO, CoO, ZnO, Y2O3 plus a good number of MTI substrates if any one out in probe-land is looking to trade.

Yes, I agree that natural materials are pretty much a waste of time.  They tend to be heterogeneous, contain inclusions and generally available in limited quantities. Whereas high purity synthetics can be replicated perpetually as necessary.  If we can produce a 99.999% pure synthetic Mg2SiO4, we can always produce more 99.999% pure synthetic Mg2SiO4.

What would be really interesting is locate sources of high purity synthetic minerals (or oxides) in the several hundred (or more) gram quantities that we can utilize for global microanalysis standard mounts.

Can you provide more information on these synthetic minerals/oxides for instance, where you got them and what quantities might they available in and with what purities?  The FIGMAS group should soon have funding for commercial purchases. Right now we are trying to locate any and all sources: commercial, national labs, academic or otherwise.

[Dave C]

The synthetics listed above were acquire from Commercial Crystal Laboratories in Florida.  Unfortunately it looks as though they are no longer in business.

[crystalgrower]

It is possible to find good MnSiO3 (rhodonite) that is homogeneous and beam stable.  Try a good mineral dealer including a seller of gemstone beads.  You will have to live with 2-3 percent each of Mg Ca and Fe but you will not pay $1000 per gram.
Other option is to look for a dark red material that turns out to be a solid solution of ZnO and MnO.  It is single crystals collected from the chimney wall of primary ore processing.   Try (google) Gifts from the Earth mineral shop in Toronto.  Also not $1000 a gram.  You will have to assay it yourself. 

[Probeman]

It is possible to find good MnSiO3 (rhodonite) that is homogeneous and beam stable.  Try a good mineral dealer including a seller of gemstone beads.  You will have to live with 2-3 percent each of Mg Ca and Fe but you will not pay $1000 per gram.
Other option is to look for a dark red material that turns out to be a solid solution of ZnO and MnO.  It is single crystals collected from the chimney wall of primary ore processing.   Try (google) Gifts from the Earth mineral shop in Toronto.  Also not $1000 a gram.  You will have to assay it yourself.

If Dave is interested in MnSiO3 for use as a standard then the assay could cost $1000 anyway. For me at least, $1000 for a high purity synthetic crystal, would be money well spent.

Especially if there is no Fe present in the synthetic material, so that it could also be utilized as an interference standard for Mn Kb on Fe Ka.  And also as a MAN background standard for elements other than Mn and Si.

We need to stop raiding our mineral collections for such "standards" and work together to procure high purity (end-member) synthetics.   MnSiO3 would be an ideal synthetic material for global distribution if it can be synthesized in sufficient quantities.

20 years ago I obtained high purity synthetic MnO from the Purdue University Crystal lab and Mn2SiO4 from Lynn Boatner at Oak Ridge National Lab.  They are perfect for use as primary, secondary, interference, MAN and blank standards and are still in use today. 

If these materials have been synthesized in the past, maybe they can be synthesized again, but this time in sufficient quantities (couple hundred grams?), enough for global distribution.