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Identity HelpUnknown fluorescent mineral

1st Nov 2016 13:16 UTCJoshua Chambers

Hi all

This one was given to me with no locality or name. Difficult to test hardness as the mineral in question is a coating and just crumbles off (plus the crystals are tiny). Vitreous lustre, fluorescent green under SW UV. I'm thinking perhaps adamite. Whilst looking under the microscope, I noticed some crystals are octahedral in shape, however difficult to see in the photos. Specimen is roughly 6cm in size. Im ight be able to post a photo of the fluorescence later, but will need to wait tilll night.

(Under 20x mag)

Any help appreciated

Thanks

Josh

1st Nov 2016 19:21 UTCErik Vercammen Expert

Josh,

Keep the crystals that crumbled off: try if one fizzes in acid, try to scratch known minrals with them. The answers on these questions will help a lot, for it is impssible to judge just on the pictures.

1st Nov 2016 19:28 UTCSteve Hardinger 🌟 Expert

Colorless adamite wouldn't be my first guess. I might guess willemite.

1st Nov 2016 22:59 UTCJoshua Chambers

I put some crystals in vinegar, and as far as I could see, no reaction. I also placed a drop on the specimen and still no reaction under magnification. I also tried hardness test and it scratched steel with ease (more than 5.5)

Thanks

Josh

2nd Nov 2016 00:42 UTCSteve Hardinger 🌟 Expert

How did you manage an accurate hardness test with crystals so tiny? Are you sure you were testing the hardness of the white unknown, and not the rock matrix?

Posting a color-accurate photo of the fluorescence would help us identify your unknown.

2nd Nov 2016 12:05 UTCHarold Moritz 🌟 Expert

Could be quartz crystals overlying a layer of green-fluorescing chalcedony.

2nd Nov 2016 16:02 UTCJoshua Chambers

Hi Steve, thanks for your replies. An accurate hardness test is difficult, but i tried to test with minimal pressure to try to avoid breaking through the crystals to the matrix. However, I would take the hardness test with a pinch of salt.

Hi Harold, thank you for the suggestion. Is this still a possibility after viewing the photo?

Here is a photo of the specimen under SW UV, LW UV shows no fluorescence.

I tried to take the best picture possible, but I may try when its dark, to see if i can get a better photo.

Also, there are some purple bits on the specimen (under UV), I may be wrong but there is some what I think to be another mineral (natrolite?) on the specimen

Perhaps the green fluorescent mineral has grown over the other mineral

Thanks

Josh

3rd Nov 2016 16:42 UTCJoshua Chambers

Any ideas

Thanks

Josh

3rd Nov 2016 16:51 UTCHarold Moritz 🌟 Expert

Can't tell much detail from the photo, but the fl. color and the closeup of the crystals suggests maybe willemite.

4th Nov 2016 14:18 UTCJoshua Chambers

Ok, thanks for the suggestion. I will probably put down Willemite for the moment until I can get it analysed.

Thanks

Josh

4th Nov 2016 15:30 UTCPeter Slootweg 🌟

It really looks like this: https://commons.wikimedia.org/wiki/File:Talmessite-Austinite-230173.jpg#/media/File:Talmessite-Austinite-230172.jpg

according to Hyrsl in his book minerals and their localities austinite sometimes shows a green fluorescence.

Although i admit it is hard to tell from just a photo it might be helpful.

Peter

4th Nov 2016 16:41 UTCJoshua Chambers

Hi Peter, thanks so much for the information, without it, it would still be labelled Willemite. This specimen resembles Gold Hill Mine Austinite very closely in both SW UV and visible light. For me, this specimen is very likely from this locality, but I'm only a beginner, what do others think?

Here's another photo I took of the 'austinite' after finding out about austinite being a possibility.

Also what do you think this mineral is on the same specimen?

Thanks

Josh

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