FMF - Friends of Minerals Forum, discussion and message board

[Jim Robison]

AM

Your latest Tsumeb smithsonite is beyond lovely. Very nice indeed. The yellow bleb inclusions are commonly attributed to either cadmium or greenockite (cadmium sulfide). Unfortunately, there is not any analysis I am aware of to confirm this, but it is the logical mineral. I have several in my Tsumeb smithsonite suite, and they all came with that attribution.

It would be very interesting to see a magnified view of the edge of the specimen. Tsumeb dolomite casts (epimorphs) are a particular passion of mine, and whenever I see a Tsumeb cast I am always suspicious. It does appear, in a couple of places, that there is a thin brown layer separating the quartz and the smithsonite. If present, it would be a very good indicator for dolomite stained by iron oxides. If it is indeed a cast, then this would be the first piece I have seen with quartz in association. A very rare critter indeed.

[am mizunaka]

Jim, I have taken a photo of the edge of the piece as well as what appears to be a seam running through part of the shell.

[Jim Robison]

Mike Your excellent new pics have a puzzle or two in them. On the second shot, with the layered material it seems most likely you are looking at dolomite. The first pic has an anomaly in that there is an obvious area where there is no intermediate material between the two sides. Very unusual. So let's back up a bit.

I went back to much expanded views of the first two pics, and am wondering about the quartz ID. Smithsonite can display a habit much like your piece shows. Have you checked hardness and/or dilute HCL reaction?. I observed a few areas where it appears there are clear rhombs, consistent with smithsonite, and with a wavy surface texture similar to some smithsonite. I think calcite is unlikely. There do not appear to be many, if any, typical quartz terminations.

Looking back at the first two pics in an expanded magnified view, there is clear evidence on the bottom of one view of a typical dolomite cast layer. There are some unusual things happening here. Fascinating specimen.

[am mizunaka]

Jim, I have not checked the hardness or tried to do an dilute HCL reaction test.

[Jim Robison]

Mike

A simple scratch test with a steel needle in an out of the way place on the clear crystals would give a good indicator on the quartz versus smithsonite question.

I've been reminded by a good Tsumeb oriented friend that I was probably premature in calling it a dolomite cast. Indeed, a test of the brown layer, and another of the white grainy material would answer the question and if you are so inclined, that would be the way to go. Conversely, it may not be worth spending the money to get an answer.

Your excellent high resolution pictures, with the ability to zoom on a small area, are really fantastic. I always look forward to seeing your work, and now that I've belatedly realized what I can look at in detail they add wonderfully to your work.

The ID of the rock is interesting, and I would love to have the piece in hand for close examination, but the pictures get me really close. Thanks, Jim

[am mizunaka]

Jim, I took a needle to a small clear crystal on the backside and it did not scratch it.

[am mizunaka]

The quartz with rutile is from a small find found in 2001/2002 near the Rist Mine in Hiddenite, North Carolina. The smoky quartz is very glassy and has distinct zoning that is not clearly visible in the photograph. The red arrow marks a movable bubble.

[am mizunaka]

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[Mike Wood]

Lovely quartzes from Rist Mine, Mike. The blue Baryte specimen from Morrocco looks mouthwateringly good, and excellent contrast with the matrix!

Thanks, Mike

[am mizunaka]

Thanks Mike. I really like the Baryte specimen too and I think the quartz pieces are a little different than the usual for that locality.

[Tobi]

[am mizunaka]

Tobi, I think that the white coating is a fine layer of quartz.

[Tobi]

[Roger Warin]

Delicate pictures for these Barytes.
Bravo.
Roger.

[am mizunaka]

Tobi - I would say that the Barytes are a single generation with the possible exception being the largest visible Baryte crystal.

Thanks Roger. This was one of the few pieces I have run across with no damage.

[am mizunaka]

[am mizunaka]

[am mizunaka]

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[am mizunaka]

[Philip Mostmans]

In the third to last post you mention Dayu. Co. for both Fluorites. How sure are you about the provenance? I got a very similar piece at a show last year, labeled as Yaogangxian...