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GeneralBritholite - Kyshtym, Urals Region, Russia

27th Sep 2017 04:33 UTCChristopher O'Neill

Hello,

I can't identify associated minerals in this particular specimen and there are not many specimens from this region posted in MINDAT that I can visually reference. I suspect the britholite (Ce) is the reddish crystalline but I am puzzled by the resinous-like yellow mineral. This specimen also has associated minerals that are fluorescent on short and long-wave UV.

Is there anyone familiar with this region and it's minerals?

I can attach more pictures to responded thread.

Regards,

Chris

27th Sep 2017 12:58 UTCPavel Kartashov Manager

At the first photo I see reddish hematitized microcline and yellowish quartz.

Fluorescention of these samples will give nothing to their identification.

The last photo shows rock quite different from typical REE-silicate nodules of Mochalin Log.

I am think, here is some misunderstanding with locality or both with locality and mineral identification. What is size of the sample?

The largest REE pebble from Kyshtym which I held in my hands was 4x2.5x1.5 cm.

In any case the rock is too light-colored in comparison with typical Kyshtym pebbles, which are dark-brown, black, brownish-black etc. Look for example https://www.mindat.org/photo-63545.html - lustrous brown phase at the left end of the sample is britholite (lessingite). And of course 99% of Mochalin Log material is represented by pebbles in different grade waterworn.

27th Sep 2017 17:20 UTCPavel Kartashov Manager

This is section of a classic REE ovoid from Kyshtym.

Its central part is composed by yellowish Bastnasite-(La) and brownish glassy Britholite-(Ce) (var. Lessingite) intergrowth surrounded by brownish-black rim of Allanite-(La).

Here are arrowed some grains of Britholite-(Ce) on break side of the ovoid.

All this not too much is similar to your sample.

27th Sep 2017 17:29 UTCPavel Kartashov Manager

I am sorry (now I look your post on normal monitor), the yellowish phase at your the first photo isn't quartz, but more similar to gummite from NE American pegmatites. The pink phase may to be zircon (var. cirtolite). Green fluorescention of later uranoan phases confirms this assumption.

Here are too many of quartz and feldspar in your sample for Kyshtym material.

27th Sep 2017 18:05 UTCChristopher O'Neill

Pavel,

Thanks for your reply.

The specimen is 7.5 x 5.5 cm and is only slight radioactive.

The yellow is resinous (gummite-like) and not quartz, however very low radioactivity compared to Ruggles Mine type gummite specimens

There is also minor orange fluorescent mineral in long-wave UV.

The label also states NEAR Kyshtym, which may be open to many possibilities for location.

Here are some additional pictures

27th Sep 2017 18:21 UTCPavel Kartashov Manager

There is the single find of macroscopic britholite in whole this region - Mochalin Log.

If your sample indeed is from Southern Ural it able to be only hydropyrochlore (yellow lustrous phase) from nephelin-syenite pegmatites of Vishevye Mts. But it usually associated with zircon of different appearance with strong orange-yellow fluorescention.

Do you see in your sample obvious nepheline (var/ eleolite)? Or obvious quartz?

As I said from the beginning, this is wrong both mineral name and wrong locality at the label.

28th Sep 2017 03:50 UTCChristopher O'Neill

Thanks Pavel,

We may not ever know the locality but I will eventually send the red and orange minerals for EDS analysis.

Regards,

Chris

28th Sep 2017 16:36 UTCPavel Kartashov Manager

I had consulted about your specimen with the leading systematic collector in the region with 50-year expirience - Sergei Kolisnichenko (aka Sanarka). He also didn't recognize the sample and hasn't any idea on its possible locality in Kyshtym area.

28th Sep 2017 18:12 UTCChristopher O'Neill

Pavel,

Thanks for your time and effort (and thank Sanarka as well).

Regards,

Chris

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