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Identity HelpHarstigen Mine - Caryopilite?

18th Mar 2015 06:07 UTCChristopher O'Neill

Hello,

I am trying to determine is the following specimen is indeed caryopilite.

Although it appears that the light brown caryopilite displays a garnet-like dodecahedral, stair-step faces, the last photos indicates it does not have the typical garnet cleavage or fracture and is more sub-conchoidal and smithsonite-like. It is associated with neoticite balls that are actually deep red and not black. This caryopilite also resembles the caryopilite in this Harstigen specimen as well. http://www.mindat.org/photo-80722.html (which is posted under calcite and lists caryopilite as an associated mineral). Are there any Harstigen experts out there who can confirm what this is? I can provide additional photos.

Many Thanks,

Chris

18th Mar 2015 08:44 UTCKnut Eldjarn 🌟 Manager

Chris,

The matrix of caryopilite from Harstigen is often a yellow to brownish garnet (andradite). Caryopilite has a radial structure and a light brown colour in fresh samples but it is often covered with or altered to black Mn-oxides. I suspect what you have is a specimen with andradite in areas covered with a thin layer of caryopilite mostly altered to black Mn-oxides.

Knut

18th Mar 2015 09:09 UTCKnut Edvard Larsen 🌟 Manager

If you look closely at the photo http://www.mindat.org/photo-80722.html , you see that there also is a more reddish brown, reniform mineral present. I think this is the caryopilite. Note the micalike structure of the mineral in the cleavages.

The more light brownish mineral more to the left, however, looks more similar to the one in your specimen. My best guess for both are garnet.

18th Mar 2015 14:14 UTCReiner Mielke Expert

Hello Chris,

I agree with Knut, I can see three different minerals in that photo not two. That is not to say that there could not be two different phases of caryopilite but a simple harness test should tell you if it is garnet or not.

18th Mar 2015 14:25 UTCAndré Heyninck

Hi Christopher,

Several times I was on the dump in Harstigen but I'am not a specialist.Very hard to determinad them.

I think the yellow mineral is garnet and the black some oxide of Mn-oxides.

Best regards,

André.

18th Mar 2015 16:42 UTCUlf Nyberg

Knut is mostly right in his description, but the black colored in close up picture reminds mostly on hisingerite.

None caryopilite observed. Test the bubbles in picture one with HCl, they can be calcite with a Mn-oxided surface.

Ulf

18th Mar 2015 17:38 UTCChristopher O'Neill

All,

First off, thanks for all your input on this.

I have a section I will be sending out for EDS analysis but in the mean time I checked hardness.

Easily scratch calcite

Easily scratch baryte

Easily scratch fluorite

Easily scratch fluorapatite

Does not scratch almandine

Does not scratch quartz

What I also noticed (and outline in the photos #1 and #3), is what appears to be a thin andradite overgrowth

upon another yellow mineral (which could be andradite as well).

Only thing that puzzles me is that the cleavage or fracture of the underlying yellow mineral in some areas

is not typical of the garnet I'm accustomed to. You see this in the upper right of photo #2 and in photo #3

18th Mar 2015 19:46 UTCReiner Mielke Expert

I've found that layered or zoned andradite breaks in unusual ways.

19th Mar 2015 11:07 UTCRock Currier Expert

Many garnets are zoned with a shell like nature. They are generally not those that collectors like to add to their collections.

31st Mar 2015 06:03 UTCChristopher O'Neill

Hello again,

I sent two crystalline samples for EDS analysis and they both indicate "spessartine". Would you all agree?

Does the Mn / Fe spike indicate something otherwise?

I would like to post this specimen, as it is an interesting assemblage of minerals for this locality.

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