This is a quiz I don't know the answer to myself. I bought this interesting slide on eBay. It has some pretty red crystals and a rather enigmatic label. First a rather bad macro shot of the subject and one of the label.
It doesn't look like a mineral, but 'porphyrins' are a class of complex organic molecules of biological origin, only fairly recently fully understood https://en.wikipedia.org/wiki/Porphyrin . They are not very stable and seem somehow unlikely to be the true subject of this rather old looking microscope slide.
Looking under the microscope reveals rather beautiful fern shaped bright red crystals. There are also some smaller colourless cubic crystals resembling common salt NaCl.
Leitz X10 plan fluorite objective, diffused incident illumination.
Allowing the tiniest trickle of transmitted light simultaneously, shows this:
Leitz X6.3 planfluorite objective, incident light plus highly attenuated transmitted light (ND filters).
As can be seen from the macro shot the crystals are embedded in some sort of yellowish coloured matrix.
Leitz X10 plan fluorite objective, incident light plus highly attenuated transmitted light (ND filters).
Anyone any idea what these crystals might truly be?
Some puzzling crystals
Moderators: rjlittlefield, ChrisR, Chris S., Pau
- Cactusdave
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Some puzzling crystals
Leitz Ortholux 1, Zeiss standard, Nikon Diaphot inverted, Canon photographic gear
Really no idea, just some speculative clues:
- porphyrine as synonym of porphyrin (the nitrogenated cycle present in chlorophyll and proteins like hemoglobin) doesn't seem to fit here
maybe something more exotic
https://en.oxforddictionaries.com/definition/porphyrine
The slide seems a petrological thin section, if so it may refer to porphyr, an igneous rock with big crystals in a matrix of small crystals or glass. The term porphyr was used in the past (and still is in ambits outside Petrology like Archeology) in a much less strict sense, so maybe it could fit.
https://books.google.es/books?id=yLc7AQ ... gy&f=false
Take a look under cross pol like petrologists always do and post your results
- porphyrine as synonym of porphyrin (the nitrogenated cycle present in chlorophyll and proteins like hemoglobin) doesn't seem to fit here
maybe something more exotic
https://en.oxforddictionaries.com/definition/porphyrine
The slide seems a petrological thin section, if so it may refer to porphyr, an igneous rock with big crystals in a matrix of small crystals or glass. The term porphyr was used in the past (and still is in ambits outside Petrology like Archeology) in a much less strict sense, so maybe it could fit.
https://books.google.es/books?id=yLc7AQ ... gy&f=false
Take a look under cross pol like petrologists always do and post your results
Pau
I can think of a couple of possibilities.
1) A thin section of the mineral Abelsonite, it is described as a "nickel porphyrin". https://www.mindat.org/min-1.html
2) A sample related to deposits of decaying organic matter and probably related to the mineral struvite. This mineral has been found in animal farms sumps, in Spain it is known as purines pits. http://espiadellabo.com/2016/09/noticia ... e-la-vida/
1) A thin section of the mineral Abelsonite, it is described as a "nickel porphyrin". https://www.mindat.org/min-1.html
2) A sample related to deposits of decaying organic matter and probably related to the mineral struvite. This mineral has been found in animal farms sumps, in Spain it is known as purines pits. http://espiadellabo.com/2016/09/noticia ... e-la-vida/
- Cactusdave
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I suppose Pau's obscure Australian tree alkaloid is a definite possibility. That's exactly the kind of thing the Victorian slide makers liked, but it's supposed to be colourless unless reacted with strong acids. Images of sections of porphyry minerals from the web don't look anything like my specimen. Abelsonite was only discovered in 1975 and this slide surely well pre-dates that. The matrix the crystals are in looks more like fixed gelatine or Collodion than a mineralogical matrix to me.
Leitz Ortholux 1, Zeiss standard, Nikon Diaphot inverted, Canon photographic gear
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- Cactusdave
- Posts: 1631
- Joined: Tue Jun 09, 2009 12:40 pm
- Location: Bromley, Kent, UK
Graham - I don't think it's Porphyry.
David
IMHO it looks more like chemical crystals embossed in a matrix rather than a petrological section. The use of the word 'section' on the label may be misleading. Possibly it may mean 'part of' or 'piece of' rather than a thin section as we are used to thinking of it.Images of sections of porphyry minerals from the web don't look anything like my specimen.
David
Leitz Ortholux 1, Zeiss standard, Nikon Diaphot inverted, Canon photographic gear