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Improving Mindat.orgSpinel Group (Missing Members)

4th Sep 2012 21:54 UTCDaniel Helman

Can you update the Spinel Group page, to include such members as are listed here:

http://tw.strahlen.org/systematik/systematik_oxide_b.html

Thanks!

Daniel Helman

Long Beach, California

5th Sep 2012 01:25 UTCPavel Kartashov Manager

Fixed.

But note that http://tw.strahlen.org/systematik/systematik_oxide_b.html also contains errors:

Filipstadite isn't true Spinel

Ulvöspinel photos on the site aren't real Ulvöspinel but rather Spinel itself. Ulvöspinel is metallic-black mineral.

5th Sep 2012 10:00 UTCThomas Witzke Manager

On my homepage (tw.strahlen.org) I followed the classification from the official IMA list

(http://pubsites.uws.edu.au/ima-cnmnc/IMA2009-01%20UPDATE%20160309.pdf)

In this list, filipstadite is placed in group 4.BB.05, the spinel group.

The ulvöspinel photos on my homepage are from a specimen, from which a crystal was taken for microprobe analysis and found to be ulvöspinel and not spinel. I think it is impossible to say just from a photo if a sample is ulvöspinel or not.

Thomas

6th Sep 2012 02:32 UTCPavel Kartashov Manager

Filipstadite was entered in the group list.

Thomas Witzke Wrote:

-------------------------------------------------------

> The ulvöspinel photos on my homepage are from a

> specimen, from which a crystal was taken for

> microprobe analysis and found to be ulvöspinel

> and not spinel. I think it is impossible to say

> just from a photo if a sample is ulvöspinel or

> not.

>

> Thomas

Dear Thomas,

I don't know who and how tested your specimen on microprobe. BUT, would you trust to somebody, who would show you light lilac transparent tabular crystal and tell you, that this is ilmenite?

Real ulvöspinel is opaque with metallic lustre mineral.

You may to send me 0.5-0.3 mm particle of your "ulvöspinel " and we'll look, how much aluminium it contains. ;)

Pavel

14th Sep 2012 06:35 UTCThomas Witzke Manager

Dear Pavel,

I made the analysis self (and you can be sure, I made in the last 25 years several 1000 analyses of minerals and other materials). There is no Al in this crystals above a trace level. And there is no exsolution of ilmenite in the crystals.

The crystals are completely opaque and with a metallic lustre in the inside. There is apparently just a very thin film on the surface that change the colour impression.

Thomas

14th Sep 2012 22:32 UTCPavel Kartashov Manager

Dear Thomas,

in such case these are great specimens, my congratulations!

But don't you think, that it would be good to state all mentioned above conditions in captions to these photos? Too many usual collectors try to "identify" their minerals only visually, using photos from databases. These photos aren't fit for such method, because colours and visual transparency of the mineral are reflected wrong.

Kind regards,

Pavel

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