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Identity HelpNickeline dendrites from Belorechenskoye deposit, Adygea, Russia

16th Aug 2010 19:19 UTCSergey Sayamov

I'm having problems identifying a specimen of nickeline dendrites from Belorechenskoye (Dakhovskoye) deposit, Adygea, Russia.

Specimen (polished plate) is 3 x 2 x 0.3 cm and gives about 1500 microRoentgens per hour which indicates not only the nickeline is here :)

Some other micro minerals are inside the dendrites and I hope someone familiar with the ore research of the deposit (I believe Pavel made some

research on these :) ) will help me.

SO:

1. NickelineDendrites5 is a normal light pic of the specimen - I wonder if the black dots are uraninite

2. I bet the darker areas on reflected light photos are the same black, BUT here we have another whitish mineral forming tiny grains inside the black.

What can it be? Some other Ni arsenate?

3. NickelineDendritesRL18 and 19 - the silvery white mineral forms euhedral crystals (and it's not of a dendritic shape if it'll be gerrsdorfite)

Photos will be in 2 next posts.

Any ideas will be highly appreciatiated.

16th Aug 2010 19:21 UTCSergey Sayamov

Here are the photos...

16th Aug 2010 19:25 UTCSergey Sayamov

And the last pics.

16th Aug 2010 22:05 UTCRob Woodside 🌟 Manager

The last photo RL 19 looks soft enough to be galena. Is it isotropic? Your guess of Arsenides for other is probably right. Unless some one is very familiar with this material, you should probe it.

17th Aug 2010 00:00 UTCDavid Von Bargen Manager

I would expect that there could be other nickle arsenides/sulfarsenides in the ore in addition to uraninite/pitchblende. The lighter gray minerals could be rammelsbergite or even nickle-skutterudite. If you have some cross cutting relations, it could also contain gersdorffite.

You tend to get increasing arsenic contents as the ore forming solutions cool so the niccolite will tend to be in the cores of the masses. You might want to look at the section under polarized light.

With the polish quality, I would expect to see triangular pits if the gray material was galena.

20th Aug 2010 13:25 UTCSergey Sayamov

David,

Yes, it's possible to check it under polarized light, but

what should I pay attention to? anisotropy?

20th Aug 2010 15:02 UTCDavid Von Bargen Manager

Yes, the various nickel arsenide/sularsenide and sulfides have different optical characteristics thast will help you narrow down the identifications. Niccolite is strongly anisotropic so you can see how the various masses grew (plus it is just plain pretty)

20th Aug 2010 16:43 UTCSergey Sayamov

Hmmm... maybe the scope isn't too good or I still can't see the anisotropy. Here's 2 pictures, parallel and crossed polars. Do they show something? Or should I slowly turn the stage and make video?

I'll hope to make some better pictures tomorrow... Maybe I should try a smaller magnification to see different dendrites at the same time. I'll let you know.

20th Aug 2010 17:36 UTCDavid Von Bargen Manager

If you turn the stage, the color can vary between a pink and blue. Other arsenides can also show some anisotropy. but nowhere near as strong. Looks like you might have some rammelsbergite surrounding the niccolite. These assemblages are extremely mineral rich and usually can contain 20-30+ minerals in the deposit.

22nd Aug 2010 20:35 UTCSergey Sayamov

David,

Well, I tested the anisotropy and frankly I can't make any new photos... anisotropy, if present, is very weak yellow to pink, not distinct blue to pink... Do this mean the main mineral isn't niccolite? Dendrites from Belorechenskoye generally consist of niccolite with hersdorffite, can it be the whole dendrite is hersdorrfite ( which is cubic, and I suppose isotropic...) ?

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