[meteorite-list] Rainbow Fusion crust

From: Göran Axelsson <axelsson_at_meteoritecentral.com>
Date: Fri, 22 Jul 2011 10:33:09 +0200
Message-ID: <4E2935C5.7000107_at_acc.umu.se>

Rainbow effect on minerals, oil on water, soap bubbles and other
examples comes from an optical effect in thin layers.

When light is reflected on a surface like a mirror it is reflected
equally in every wavelength and you don't get any effect. But if there
is a thin layer that some of the light is reflected from then you get
interference. If the extra distance travelled is equal to one or more
full wavelength of a colour then you get constructive interference and
that colour is enhanced. But if the distance travelled is equal to a
half plus zero or more full wavelength then you get destructive
interference and that colour is dampened.
The best example is a drop of oil on water where you could watch the
colours change while the oil layer gets thinner.

http://en.wikipedia.org/wiki/Thin-film_interference

My guess is that the colour seen on these meteorites comes from a thin
oxidation layer or maybe from oil from the hands that handled the
meteorite. Anyhow, you need a quite glossy surface to get that effect so
it is a really fresh meteorite.

Nice pictures!

/G?ran

Martin Altmann skrev 2011-07-21 19:39:
> Just some hours ago,
> list-member Stephan Kambach sent me a picture of a Murchison individual,
> showing such a rainbow effect.
>
> Best!
> Martin
>
> -----Urspr?ngliche Nachricht-----
> Von: meteorite-list-bounces at meteoritecentral.com
> [mailto:meteorite-list-bounces at meteoritecentral.com] Im Auftrag von Mike
> Bandli
> Gesendet: Donnerstag, 21. Juli 2011 19:21
> An: 'Gary Fujihara'; 'Marc Fries'
> Cc: meteorite-list at meteoritecentral.com
> Betreff: Re: [meteorite-list] Rainbow Fusion crust
>
> I've seen this "rainbow effect" in the fusion crust of a few specimens in my
> life including Murchison, Ash Creek, and Buzzard Coulee. Jim Strope has a
> great example of Murchison with this coloration in the crust here:
>
> http://catchafallingstar.com/murchison723i.JPG
>
> The complete page:
>
> http://catchafallingstar.com/murchison723.htm
>
> Very interesting. I would love to know what causes it.
>
> ----------------------------------------------
> Mike Bandli
> Historic Meteorites
> www.HistoricMeteorites.com
> and join us on Facebook:
> www.facebook.com/Meteorites1
> IMCA #5765
> -----------------------------------------------
>
>
> -----Original Message-----
> From: meteorite-list-bounces at meteoritecentral.com
> [mailto:meteorite-list-bounces at meteoritecentral.com] On Behalf Of Gary
> Fujihara
> Sent: Thursday, July 21, 2011 10:06 AM
> To: Marc Fries
> Cc: meteorite-list at meteoritecentral.com
> Subject: Re: [meteorite-list] AD: Special: Truly baffling& sensational
> Howardite - NWA 6709 - absolutely stunning and very fresh.
>
> Great observation Marc. Iridescence is common on many pahoehoe lava flows
> on the Big Island, and is quite remarkable to see.
>
> Sent from Gary's iPhone
>
> On Jul 21, 2011, at 6:53 AM, Marc Fries<mfries8 at hotmail.com> wrote:
>
>> Mild oxidation of silicate glass (fusion crust in this case) can produce a
> rainbow effect, too. I've seen this in basalts in the field. I think it is
> from a sheen of iron oxides created as the iron and/or sulfide weathers out.
>> Cheers,
>> Marc Fries
>>
>> On 7/21/11 1:13 AM, Aubrey Whymark wrote:
>>> Hi
>>>
>>> The rainbow colour looks like oil to me. Maybe someone has used oil or
> WD40 to clean it. I sometimes encounter 'rainbow' tektites and the guys want
> extra because of it - in reality it is due to oil contamination, probably
> from the mining operations.
>>> Regards, Aubrey
>>> www.tektites.co.uk
>>>
>>>
>>>
>>> --- On Thu, 21/7/11, Martin Altmann<altmann at meteorite-martin.de> wrote:
>>>
>>>> From: Martin Altmann<altmann at meteorite-martin.de>
>>>> Subject: Re: [meteorite-list] AD: Special: Truly baffling& sensational
> Howardite - NWA 6709 - absolutely stunning and very fresh.
>>>> To: meteorite-list at meteoritecentral.com
>>>> Date: Thursday, 21 July, 2011, 0:33
>>>> Hi Mike,
>>>>
>>>> no worries, neither we understood it like that.
>>>>
>>>> Of course, if one looks to the photos, the first idea,
>>>> which comes to one's
>>>> mind is: oil.
>>>> No idea, what causes this effect, maybe the composition.
>>>> Also that strange
>>>> tint the cut faces reveal.
>>>>
>>>> And especially worrying is the variety of the odd
>>>> inclusions. I mean
>>>> normally we all get already excited, whenever we find a
>>>> carbonaceous
>>>> fragment in a howardite,
>>>> but what that stone has all for strange clasts - that is
>>>> really not normal
>>>> anymore.
>>>>
>>>> Since 1999 Stefan is in Morocco and since then we certainly
>>>> had quite a
>>>> bunch of materials in our hands,
>>>> but such a weird polymict one - extremely unusual.
>>>>
>>>> And it seems that many collectors feel the same, if after
>>>> such a short time
>>>> now only three slices are left.
>>>>
>>>> Now all of the smaller ones are gone, sorry for that. But
>>>> we have still a
>>>> slice left, which we could subdivide into small partslices,
>>>> if desired - but
>>>> for that one has really to raise his finger.
>>>>
>>>> For the moment!
>>>> Martin
>>>>
>>>> -----Urspr?ngliche Nachricht-----
>>>> Von: meteorite-list-bounces at meteoritecentral.com
>>>> [mailto:meteorite-list-bounces at meteoritecentral.com]
>>>> Im Auftrag von Galactic
>>>> Stone& Ironworks
>>>> Gesendet: Donnerstag, 21. Juli 2011 00:48
>>>> An: Chladnis Heirs
>>>> Cc: meteorite-list at meteoritecentral.com
>>>> Betreff: Re: [meteorite-list] AD: Special: Truly baffling
>>>> & sensational
>>>> Howardite - NWA 6709 - absolutely stunning and very fresh.
>>>>
>>>> Hi Martin,
>>>>
>>>> I didn't mean to impeach the meteorite, I was just
>>>> curious.
>>>>
>>>> This is indeed a mystery. Have any scientists offered
>>>> or agreed to
>>>> look at it? Perhaps hit the rainbow area with the
>>>> microprobe or SEM?
>>>>
>>>> Aesthetically speaking, it's gorgeous and looks like Mother
>>>> of Pearl. :)
>>>>
>>>> Best regards,
>>>>
>>>> MikeG
>>>>
>>>> --
>>>>
> ----------------------------------------------------------------------------
>>>> -----
>>>> Galactic Stone& Ironworks - Meteorites& Amber
>>>> (Michael Gilmer)
>>>>
>>>> Website - http://www.galactic-stone.com
>>>> Facebook - http://tinyurl.com/42h79my
>>>> News Feed - http://www.galactic-stone.com/rss/126516
>>>> Twitter - http://twitter.com/galacticstone
>>>> EOM - http://www.encyclopedia-of-meteorites.com/collection.aspx?id=1564
>>>>
> ----------------------------------------------------------------------------
>>>> -----
>>>>
>>>> On 7/20/11, Chladnis Heirs<news at chladnis-heirs.com>
>>>> wrote:
>>>>> No, it's natural!
>>>>>
>>>>> Martin
>>>>>
>>>>>
>>>>> -----Urspr?ngliche Nachricht-----
>>>>> Von: Galactic Stone& Ironworks [mailto:meteoritemike at gmail.com]
>>>>> Gesendet: Mittwoch, 20. Juli 2011 23:24
>>>>> An: Chladnis Heirs
>>>>> Cc: meteorite-list at meteoritecentral.com
>>>>> Betreff: Re: [meteorite-list] AD: Special: Truly
>>>> baffling& sensational
>>>>> Howardite - NWA 6709 - absolutely stunning and very
>>>> fresh.
>>>>> Wow! That is one of the most beautiful
>>>> howardites I have ever seen.
>>>>> Nice find. :)
>>>>>
>>>>> The rainbox coloration is very odd. Was the
>>>> stone cleaned at any time?
>>>>> Best regards,
>>>>>
>>>>> MikeG
>>>>>
>>>>>
> ----------------------------------------------------------------------------
>>>>> -----
>>>>> Galactic Stone& Ironworks - Meteorites&
>>>> Amber (Michael Gilmer)
>>>>> Website - http://www.galactic-stone.com
>>>>> Facebook - http://tinyurl.com/42h79my
>>>>> News Feed - http://www.galactic-stone.com/rss/126516
>>>>> Twitter - http://twitter.com/galacticstone
>>>>> EOM - http://www.encyclopedia-of-meteorites.com/collection.aspx?id=1564
>>>>>
> ----------------------------------------------------------------------------
>>>>> -----
>>>>>
>>>>> On 7/20/11, Chladnis Heirs<news at chladnis-heirs.com>
>>>> wrote:
>>>>>> Dear meteorite community,
>>>>>>
>>>>>> with this Special we have to introduce to you an
>>>> enormous oddity.
>>>>>> It is about a HED-meteorite of a kind, which we
>>>> hadn't ever seen before
>>>> in
>>>>>> our careers before.
>>>>>>
>>>>>> It came in two stones, one of them was covered
>>>> with a lush fusion crust,
>>>>>> wonderfully structured by thick and oriented
>>>> flowlines.
>>>>>> And in some parts, that very crust displayed a
>>>> gloss and a shine,
>>>>> iridescent
>>>>>> in all colours of the rainbow;
>>>>>> an effect, reminding almost to bismuth!
>>>>>>
>>>>>> Please take a look to the photos, where we tried
>>>> to captured the effect:
>>>>>> http://www.chladnis-heirs.com/new-meteorites/nwa6709.html
>>>>>>
>>>>>>
>>>>>> The interior was no less a riddle for us.
>>>>>> The distribution and sizes of the various
>>>> fragments and clasts were
>>>> unlike
>>>>>> we had seen in any polymict HED before.
>>>>>> A variety of clasts is of a kind, like we never
>>>> had recovered in any
>>>> Vesta
>>>>>> meteorite. Please take a closer look to the slices
>>>> and you will share our
>>>>>> surprise.
>>>>>>
>>>>>> And a very few of these clasts develope due to
>>>> their microscopically
>>>>>> lamellae-texture a fire like an opal, if turned
>>>> around in the light.
>>>>>> The response to a magnet is very inhomogeneous
>>>> within the slices,
>>>>>> although no differences are visible to the eye
>>>>>> and all in all the interior has a somewhat dull
>>>> yellowish tint - although
>>>>>> the material is very fresh - and that tint and the
>>>> circumstances made us
>>>>>> initially think, it might be diogenitic.
>>>>>>
>>>>>> It is under classification at Dr. Anthony Irving
>>>> and the values say, that
>>>>> it
>>>>>> is a shocked howardite.
>>>>>>
>>>>>> We crafted now a set of polished sliced of all
>>>> sizes, to share this
>>>>>> exceptional material with you.
>>>>>> Please acknowledge that we have kept the price,
>>>> despite of the for us so
>>>>>> unique properties of the material, well
>>>> affordable,
>>>>>> for everybody staying able to add a specimen of
>>>> this truly exceptional
>>>>> stone
>>>>>> to his collection.
>>>>>> And an addition it is, also for the most
>>>> experienced veteran collector.
>>>>>> Earlier today we had published the Special in the
>>>> German forum, therefore
>>>>>> not so many specimens are left.
>>>>>>
>>>>>> For the largest slice we can offer a discount as
>>>> it is the only one,
>>>> which
>>>>>> isn't coplanar.
>>>>>>
>>>>>> And finally, the specimen named "piece #2", which
>>>> we chose to illustrate
>>>>>> best that rainbow-bismuth-gloss of the fusion
>>>> crust on the first linked
>>>>>> page, is available too. It weighs 119.2g and we're
>>>> accepting offers.
>>>>>> Here you are now:
>>>>>> http://www.chladnis-heirs.com/specials/special-nwa6709.html
>>>>>>
>>>>>>
>>>>>> Best Regards,
>>>>>> Stefan& Martin
>>>>>>
>>>>>> Chladni's Heirs
>>>>>> Munich - Berlin
>>>>>> Fine Meteorites for Science& Collectors
>>>>>>
>>>>>> http://www.chladnis-heirs.com
>>>>>>
>>>>>>
>>>>>>
>>>>>> ______________________________________________
>>>>>>
Received on Fri 22 Jul 2011 04:33:09 AM PDT