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Afghanite, Calcite, Phlogopite - Badahkshan, Afghanistan

8.5.2017

This piece (as most from Afghanistan) is best displayed using multiple wavelengths.  This piece, as shown in the first pic, shows best under a combination of longwave, midwave and shortwave (fullwave), although it is very respectable under SW alone (second pic) - or even MW or LW alone.  Lots of pics as this is a very complex piece - be sure to see them all.

 

There are several afghanite crystals (orange to brown) and the matrix appears to have marialite (bright yellow) disseminated throughout, along with a bright white fluorescing mineral that is suggested to perhaps be albite. Under SW the calcite fluoresces a dark orange, and the unknown crystals fluoresce a bluish white - my guess is that the white is albite.  Under MW (only) there are areas of a strong blue fluorescence from an unknown mineral - this is one of the few examples of MW only fluorescence I have observed (several closeups of this area are shown at the bottom). Phlogopite is bright yellow under SW, shifting to a butterscotch color MW and even deeper LW (very few phlogopites have this multi-wave response). Midwave causes the calcite to pop very nicely.   Longwave brings out the orange color of the afghanite crystals.  MW and LW bring out the bright yellow of the marialite very nicely. If I were to display it under only one light, I would probably pick SW, preferably with a LW “kicker”.

 

The closeups (below the main pic in the gallery) show various interesting areas.  Note that the phlogopite on this piece is fluorescent a bright yellow SW and a butterscotch under MW. 

 A note about the blue stuff:

Most of the blue minerals from Badakshan are members of the Cancrinite Sodalite Group.  These include the following:

  • Lazurite: Na6Ca2(Al6Si6O24)(SO4,S,S2, S3,Cl,OH)2

  • Afghanite: Na22Ca10(Si24Al24)O96(SO4)6Cl6

  • Haüyne:  Na,K)3(Ca,Na)(Al3Si3O12)(SO4,S,Cl

  • Nosean: Na8(Al6Si6O24)(SO4) · H2O

  • Sodalite: Na8(Al6Si6O24)Cl2

All of these minerals are often misidentified and confused with each other.  The absence of calcium and chlorine (or the presence) is often the only characteristic separating nosean from hauyne for example; in massive form (no crystals) there is little visible difference.  Lazurite has more sulfide while hauyne has more sulfate.  Minrec reports that most lazurite is really sulfide-rich hauyne.  I’m pretty sure much of the massive material also has afghanite thrown in for good measure. So - if there are no crystals to help in the identification, the massive blue mineral could be many things.  Worse, the fluorescent activators have not been studied from this area and it’s very unclear what is going on.  But they sure do make for some confusing but beautiful fluorescent specimens.

 

 

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