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PhotosCorundum - Mogok Township, Pyin-Oo-Lwin District, Mandalay Region, Myanmar

30th Nov 2017 17:15 UTCRichard Gunter Expert

Has anyone else seen orange fluorescing crystals like these from Mogok. They do not look like normal Zircons but I don't know what else they could be given their physical properties.

30th Nov 2017 20:15 UTCHarald Schillhammer Expert

I have seen tons of stuff from Mogok, incl. zircons, but never a zircon associated with corundum in marble. I guess you should sacrifice one of those grains and have it analysed.

30th Nov 2017 20:24 UTCReiner Mielke Expert

You sure that is corundum? I have some scapolite from there that looks like that.

30th Nov 2017 20:30 UTCHarald Schillhammer Expert

Reiner Mielke Wrote:

-------------------------------------------------------

> You sure that is corundum? I have some scapolite

> from there that looks like that.

Good point, but unfortunately, the photo is so bad that a visual interpretation is almost impossible.

30th Nov 2017 21:21 UTCRichard Gunter Expert

Hi Reiner:

It is corundum. The hardness and hexagonal crystals, some double terminated, can be nothing else. The corundum crystals are light olive green with prism faces and pinacoidal terminations. The prism faces have parting planes parallel to {0001} along the length. A dark phlogopite mica is the only other phase.

The orange crystals are so small, < 1mm, that the photo is the best I can get. The orange crystals are completely gemmy and have no internal crazing; crazing seems characteristic of the zircon from Mogok. The orange fluorescence in SW UV is the same colour as other zircon crystals in my collection.

Harald:

That is why I asked as there does not seem to be any instances of corundum and zircon occurring together in the marble in the literature. Mogok was the locality on the card when I bought it in 2008.

I may have to have the orange crystals analyzed as I can find no other matches.

Thanks for the help.

1st Dec 2017 00:13 UTCRichard Gunter Expert

One more note on the corundum. It has a significant change in colour between incandescent light (olive green), sunlight (grass green) and halogen light (grey-green). The posted photo was taken in halogen light.

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