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Identity HelpUnidentified prismatic crystal with blue spinel from the Hunza Valley, Pakistan

7th Dec 2019 18:15 UTCNick Gilly

The pics aren't great but I'm interested in the pale brown long prismatic crystal that is adjacent to the face of one of the spinel crystals. It's on the right hand edge of the crystal on the left in the pic. Some kind of amphibole or pyroxene maybe? I'll see if I can take some better pics tomorrow when its daylight.

Anyone else seen anything similar with these specimens before?

7th Dec 2019 18:54 UTCJosé Zendrera 🌟 Manager

Sorry, in photo I'm not able to see a prism or any other crystal form in the brown stuff.
Matrix is marble?
Maybe phlogopite?
Can check fluorescence under short wave UV, Afghan phlogopite usually is fluorescent giving a yellowish color under SW.

7th Dec 2019 23:34 UTCNick Gilly

Hi José, and thanks for your thoughts. Yes the matrix is marble.

I have produced a new picture with the mystery crystal highlighted. I only have a LW UV source, and with this the unknown does not appear to fluoresce although the spinels do seem to fluoresce a deep purplish red. The shape doesn't look right for phlogopite or a mica-type mineral to me.

8th Dec 2019 13:49 UTCLouis Zulli

All I see is a yellow-brown blur. No crystal form is visible to my eyes. Is titanite a possibility?

8th Dec 2019 15:29 UTCNick Gilly

Hi Louis. Yes the quality isn't brilliant unfortunately. I tried taking some photos outside earlier but they came out even more out-of-focus. It's the sort of small detail that would benefit from microphotography. There appears to be just one prism face that is well-formed enough to reflect light. It's curious that it has formed along the edge of the spinel crystal, whatever it is.

8th Dec 2019 18:39 UTCDonald B Peck Expert

I can see the crystal to which you are referring. Unfortunately it is too thin to make out any detail. Wish I could help.

Don