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Feldspar Fluorescent

Costas Constantinides March 20, 2017 06:34AM
Can someone help to ID this Fluorescent Feldspar..It comes from Mica Creek. Pegmatites near Mount Isa .Qld .Australia.What type of feldspar is it likely to be.

Edited 1 time(s). Last edit at 03/20/2017 06:36AM by Costas Constantinides.
Alfredo Petrov March 20, 2017 06:45AM
perthite ?
Wayne Corwin March 20, 2017 08:08AM
Yup, perthite !
Pavel Kartashov March 20, 2017 11:05AM
Fe3+-bearing microcline.
Susan Robinson March 20, 2017 11:20AM
Perthite is not a mineral species name. To my understanding, perthite, is a term used to denote the texture of feldspar that is a mix of albite and K-spar (microcline).

Susan Robinson
Wayne Corwin March 20, 2017 11:42AM
Sorry Sue,,,, I don't know what else to call it.
Susan Robinson March 20, 2017 12:50PM
Pavel's answer might be more correct?

Susan Robinson
Ed Clopton March 20, 2017 03:32PM
Looks like perthitic microcline to me.
Harold Moritz March 20, 2017 06:14PM
Microcline - its all pretty much perthitic.
Costas Constantinides March 20, 2017 11:55PM
Thank you for answers.I read microcline fluoresced ,But since this was identified as perthite and is albite/microcline ,would the the perthite fluoresce.I should also ask is perthite a mixture or are the feldspars stratified.

Edited 1 time(s). Last edit at 03/20/2017 11:56PM by Costas Constantinides.
Harold Moritz March 21, 2017 12:20PM
Perthite is a texture, not a mineral or a mixture. The "veining" texture is from albite that has exsolved from the microcline host while in the solid state. At high temperature, when the microcline crystallized, the albite was essentially dissolved in it. At lower temp that mixture was no longer stable and over millions of years the albite exsolved out. Other examples of this phenomenon are kamacite/taenite of iron meteorites and tephroite/willemite crystals from New Jersey.

Essentially all microcline is perthitic (much of the texture can be microscopic) so I don't even consider there to be a distinction. It does not affect fluorescence of the microcline, in fact in some cases the albite will fluoresce blue and the microcline red.

In other situations, albite crystals can form on top of the albite veining in a microcline crystal!
https://www.mindat.org/photo-387758.html see child photos also
David Von Bargen March 21, 2017 01:35PM
Actually perthite is special case name for a texture for describing albite exsolution areas grown in a microcline crystal (antiperthite is microcline exsolved in albite). Other mineral pairs are usually referred to simply as exsolution features for the two minerals
Costas Constantinides March 21, 2017 11:59PM
Thank you all for help and explanations..
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