FMF - Friends of Minerals Forum, discussion and message board

[Antonio Alcaide]

[Antonio Alcaide]

The lacking of interesting examples of inclusions from my own collection (at the moment: "first the thread, then the specimen", the way the Forum influences me), I cannot help posting a couple of fine threads from the Spanish side. There we have Egor Gavrilenko, an expert in gems, to whom we owe the examples:

https://www.foro-minerales.com/forum/viewtopic.php?t=5584

https://www.foro-minerales.com/forum/viewtopic.php?t=4662

Regards

[am mizunaka]

Quartz with rutile inclusions.

[vic rzonca]

On re-reading my entry, it seems a little pedestrian to ask, is an inclusion confined to the inbound side of the of the included matrix? And do inclusions manifest themselves on the surface, where they might become a specimen on matrix? I just dropped in, pardon me.

[Elise]

[Duncan Miller]

Elise

You are scholarly, gracious, good humoured, and you write extremely well. I think there is great merit in your introducing some gemmology to this forum, Jordi's prejudice against crystal choppers notwithstanding! After all, the internal world of gemstones is also the internal world of minerals, and a crystal doesn't have to have faces to be crystalline.

I have arranged for the cutter of one of the Orange river quartz cabochons with haematite spots to bring it to our gem and mineral club meeting today, where I will photograph it and send you the photo privately, as we are now agreed the spots are artefacts, and so off topic.

Duncan

[Duncan Miller]

This is an edited re-post of a specimen in Peter Megaw's 'sand crystal' thread.

This smoky quartz with aegerine is from Malosa, Malawi. The aegerine crystals penetrate and poke out of all sides of the quartz crystal. Most of them are terminated, some of them doubly where they penetrate right through the quartz crystal. So, how did this grow? Did the aegerine nucleate before the quartz, which then partially engulfed it?

Duncan

[John S. White]

Another one, this one a bit different. This is a chlorite-included quartz from the Tipling mine, Dhading district, Nepal, in which inclusion-free quartz grew over the termination creating a scepter. The piece is 8.5 cm tall.

[John S. White]

The inclusions in quartz from Pakistan described as rutile by am mizunaka look to me very much like astrophyllite, which appears to be relatively common in quartzes from Zagi Mountain in the Northwest Frontier Province.

[al mar]

Elise, I have seen some very similar blue quartz specimens from Brazil .

[John S. White]

Here's one for Vic to scratch his head over. This is goethite in amethystine quartz from Rio Grando do Sul, Brazil. It would appear that the goethite grew first on the surface of a larger goethite-included quartz crystal, then it became engulfed by quartz. One assumes that the growth of the two minerals was almost simultaneous.

A John Koivula photo.

[silvio steinhaus]

Amethyst with various inclusions, calcite, cristobalite, goethite, and the red stuff in the picture, I do not know what it is.
The area of the photo is 14 x 12mm piece is 160 x 175mm, with many inclusions undetermined.

[vic rzonca]

It's really amazing how, on a molecular level these, these bits find themselves and arrange themselves in such a wonderful way that makes us ponder them. Simo-nucleotidic scilicic euhedral growth over goethite. I may be wrong. Just kidding, I know nothing. I still wonder what make's an inclusion. Where are it's boundaries. I would suppose it would be totally surrounded by it's binding mineral, no penetrations. Could someone clarify.

[am mizunaka]

Quartz with fluorite inclusions.

[John S. White]

The fluorite in quartz specimen just shown by Am provides an excellent opportunity to respond to Vic's question. These Madagascar specimens are really interesting because some of the fluorites are entirely embedded or inclosed in quartz and some are partially exposed at the surface. Those that are/were partially exposed are gone! The cavities are octahedral-shaped, but empty. It is very difficult to imagine how these could have been dissolved and removed via just a tiny opening where they were not covered by quartz. The piece in Am's photos beautifully illustrates this feature.

So, Vic, in my opinion inclusions do not have to be completely enclosed in a host mineral, they often extend beyond the surface. This is particularly true for extremely elongated fibrous or needlelike minerals such as aegirine from Malawi. I doubt that there is a definition in the popular literature that would exclude crystals that extend beyond the surface from being considered inclusions.