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GeneralMagnetite pseudomorph Hematite from Seriphos

19th Apr 2016 18:15 UTCGerhard Brandstetter Expert

Today i had a very nice visit from Peter Schlögl - Collector, respected dealer and personal friend from Austria. He has a brand new Information for us:

Some of you may have a nice "Hematite Iron Rose" from Avissalos, Seriphos Island, Greece. Peter sent it to the University of Natural Resources and Life Sciences in Vienna. Some XRD was done with a surprising result:

All the samples turned out to be Magnetite pseudomorph Hematite. No Hematite was left. it seems there is no Hematite on this locality!

Of course we tested all our samples - all are high magnetic. If you own such a specimen i recommend to do the same - much fun!

Nice greetings, Gerhard

Magnetite pseudomorph Hematite, with small Quartz, var. Prase 45 mm

Avissalos, Seriphos Island, Greece

20th Apr 2016 01:47 UTCRob Woodside 🌟 Manager

Gerhard, thanks so much. Could you please upload that photo as magnetite after hematite?

20th Apr 2016 02:09 UTCAlfredo Petrov Manager

Possibly not originally hematite but something else? A sulphide perhaps? Or is there detectable relict hematite? To me they do not look like typical hematite roses.

I've asked myself the same question before about the similar "hematite"(?) spheres (formed of very thin lamellar crystals) from basalt vugs in Mumbai, which are also magnetic now: http://www.mindat.org/photo-392263.html

Interesting that this similar strange phenomenon occurs in such different geological environments.

20th Apr 2016 06:49 UTCGerhard Brandstetter Expert

Rob: Of course i uploaded two photos to Avissalos locality page.

Alfredo: The only result from XRD was Magnetite - no other mineral.

I also informed some greek collectors via Facebook. Seems all our specimen are magnetic. So i would suggest to remove "Hematite" from the locality page

Of course a message to other photo owners of "Hematite" would be helpful. I know that many specimen of this type are are around. Some are more than phantastic. So i think this Information is very important for gthe proud owners. May be i am wrong - but i think up to now this find has the best samples of Magnetite pseudomorph "questionable Magnetite".

20th Apr 2016 06:53 UTCAlfredo Petrov Manager

Thanks, Gerhard.

Rob took care of it already.

20th Apr 2016 11:25 UTCUwe Kolitsch Manager

"To me they do not look like typical hematite roses."

You could probably describe them as "closed roses". Hematite may show all kinds of variants from nearly flat rosettes to such spheroidal aggregates.

A sulphide can be excluded.

20th Apr 2016 16:19 UTCRob Woodside 🌟 Manager

Gerhard said,"Rob: Of course i uploaded two photos to Avissalos locality page." Unfortunately I cleared the cache at http://www.mindat.org/loc-215527.html?cacheclear=1 and checked your photos posted at Mindat and could not find that nice rose with the prase accent that you posted at the beginning of the thread. Could you please add it to your photos in your personal gallery here.

20th Apr 2016 17:27 UTCGerhard Brandstetter Expert

Hello Rob, since yesterday the photos are in my personal gallery. Information says "pending approval".

As a normal member it is not possible to upload them directly of course.

20th Apr 2016 19:25 UTCUwe Kolitsch Manager

All approved.

20th Apr 2016 19:31 UTCPavel Kartashov Manager

Pseudomorphoses of magnetite after hematite named mushketovite - http://www.mindat.org/min-10101.html

20th Apr 2016 20:46 UTCRob Woodside 🌟 Manager

Thanks Uwe. I checked ALL photos at Gerhard's home page and I thought that picked up photos "pending approval" ?

Thanks Pavel. Much as I dislike the proliferation of names, this magnetite variety is worthy. I'll add it.

20th Apr 2016 21:32 UTCPavel Kartashov Manager

Mushketovitization is standard term during description of iron ores. Opposite term is martitization. Martite is pseudomorph of hematite after magnetite.

Usually these oppositely directed processes works on level grains and their aggregates. But sometimes they give such spectacular manifestations.

Do you think, that "magnetitization of hematite" and "hematitization of magnetite" would sounds better? In any case it would be more longer.

20th Apr 2016 22:08 UTCRichard Gunter Expert

Hi Pavel:

I had never heard of Mushketovite before. Would it apply to the Magnetite after Hematite samples from the Sterling Mine at Antwerp, New York and the Phoenix Mine, Greenwood, British Columbia as well or is it from specific iron-ore deposits?

20th Apr 2016 22:09 UTCRob Woodside 🌟 Manager

Thanks Pavel. I'll add it to the mineral list and send messages about the photos

20th Apr 2016 22:35 UTCRob Woodside 🌟 Manager

Messages sent. However both information icons of hedenbergite and hematite, which have no photos, say there is a photo of Hedenbergite and hematite. it would be helpful if one could click these to bring up the photo. I can't find this hedenbergite and hematite photo.

20th Apr 2016 22:57 UTCPavel Kartashov Manager

Hi Richard,

this term don't connected with any specific locality. Usually mushketovite is found in skarn deposits with wugs where grow hematite roses. Mushketovite from Dashkesan iron deposit in Azerbaijan is represented in any serious collection in Russia. But mushketovitization may take place in massive granular iron ores of any origin where partial reduction of iron occurs. For example, it is strange, that mushketovite roses didn't found up to now in Inner Mongolian iron skarn deposits (Huanggang e.a.).

20th Apr 2016 23:13 UTCRichard Gunter Expert

Hi Pavel:

There is a very interesting case at the Phoenix Mine, British Columbia where the ore is a combination of Cu-bearing silicate skarn and massive Cu-Fe sulphide-oxide. The Hematite roses in the skarn are not converted to Magnetite yet the Hematite roses in cavities in the sulphide-oxide are all converted to Magnetite. These two horizons can occur within meters of each other. I have posted examples of both types but I can not figure out how it happened.

21st Apr 2016 16:43 UTCUwe Kolitsch Manager

Richard: I'd guess in the cavities the oxygen fugacity is just a bit lower, possibly due to the presence of the buffering sulphide(s).

21st Apr 2016 17:35 UTCRichard Gunter Expert

Hi Uwe:

That is quite possible; otherwise the cavities have the same mineralogy. The Mushketovite blades have a secondary overgrowth of Magnetite octahedrons on the edges of the blades. In this deposit the copper is late-stage with Pyrite crystals mantled by Chalcopyrite in both the oxide and the skarn cavities.

6th Jun 2016 05:59 UTCMichael Sommers

All my Rio Marina hematite attracts magnets, along with my one piece of N'Chwaning - fairly strongly. My one rose from Minas Gerais attracts it weakly. My kidney ore style hematite pieces from England and Minnesota not a bit. Is that typical for the well-crystallized pieces, is the hematite magnetic or are they mixtures of hematite and magnetite?

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