FMF - Friends of Minerals Forum, discussion and message board

[Elise]

I wondered if any members might have an interest in sharing images of intact mineral specimens with interesting inclusions, especially the whole specimen accompanied by a detail of the inclusion(s). I think that seeing inclusions in the context of its host crystal for a variety of minerals would be fascinating - even if it is just an arrow pointing to the location of the inclusion or a description of its relationship to the host crystal structure. We've had some separate threads about specific species or types of inclusions, such as the helical one https://www.mineral-forum.com/message-board/viewtopic.php?t=1337 but maybe a thread of a more general nature would grow. I am thinking of Alfredo's quip to me which went something like "inclusions are just minerals with expertly trimmed matrix" ... or something like that.

What prompted this inquiry was that I stayed up half the night studying a collection of several dozen inclusion specimens which I only had access to for less than 24 hours before I had to return the box back across the country. Part of the fascination for me with inclusion science is learning how something came to be - studying one 400 micron mineral inclusion in detail has recently taken me to both Brookhaven and Argonne synchrotrons ( that might be considered overkill!) - there was not enough time with this collection to work out what was going on crystallographically in the pieces, which as you can imagine, is more difficult to do after its transformation by the lapidary artist. Unfortunately, most specimens I see are already fashioned into a bead or gem or sculpture etc - I am curious if there is a faction of mineral collectors who specialize in unadulterated included minerals - or maybe "rough & cuts" (or at least a polished window through which get a better view).

I am already starting this off badly - I don't have a natural specimen to share for the fashioned ones I am posting below; I can only imagine how the crystal may have appeared -- I just thought it was neat and hope that Jordi doesn't evict me as a crystal chopper. These are 2 pieces I examined last night which made me wish I could have seen the original crystal, though it is fun to also figure it out just using the microscope: The "polka dots" are centered around the c axis of the quartz, roughly indicated by my attempts to insert a line, and are apparently formed under the rhombehedral faces, 6 total with one cab showing a second set below. I assume these are phantom formations and the "blooms" are hematite - each oval is composed of hundreds of colorful concretions. Has anyone seen natural quartz crystals with these within? I think it would be a spectacular sight!

Cheers!
Elise

[Antonio Alcaide]

Great idea!! Elise: a general thread for minerals with inclusions. Recently, at the Spanish Forum, a member confessed his passion for inclusions. Despite the Spanish I give the link (interesting pictures of included new fluorites from Asturias, Spain):

https://www.foro-minerales.com/forum/viewtopic.php?p=63100#63100

I shall try to post another example later.

Regards

[Duncan Miller]

Elise

Good idea for a thread, but, if the haematite spots are arranged symmetrically around the c-axis they could be portions of a haematite skin coating the original rhombohedral faces. Clever cutting would preserve these as more or less round spots. I have seen similar stones produced from haematite-coated so-called 'Orange river' quartz from Namaqualand, South Africa. In that case they are not inclusions, but overgrowths. Are your spots embedded, or exposed?

Duncan

[am mizunaka]

Aquamarine with Ferrocolumbite inclusion.

[John S. White]

I have many examples, here is one of my favorites. I do not have a photo of the whole specimen, but will take one and post it later.

[John S. White]

Here is the whole piece. All of the side faces have been polished, otherwise you would not be able to see the inclusions. The cookeite xls are all on one plane and the apatite xls, which came later, are on another parallel plane. Again the piece is 8 cm across.

[silvio steinhaus]

Agate with Goethite inclusions.
As the total sample is 3 x 2 cm and is cut cabochon

[Elise]

[silvio steinhaus]

Quartz with inclusion of green Uvite

[silvio steinhaus]

Quartz with inclusion of green Uvite

[silvio steinhaus]

Amethyst with inclusion of Cristobalite

[Elise]

[silvio steinhaus]

Calcite with inclusion of goethite on amethyst

[Duncan Miller]

OK Elise - If I have got it right some of the 'blooms' are inside the quartz, not just on the surface. That is not the same as the cabochons I have seen cut from haematite-coated crystals, that have the red/brown patches on the outside. Thanks for the clarification. Duncan

[Peter Megaw]

Elise, you have tapped into a vein that runs rich and deep in the collector community. Mineral Inclusions is/are actually a very broad category that can be broken down on the basis of inclusion grain size (from coloring agents to mega-inclusions), related versus unrelated species (species sequentially deposited from the same fluid versus accidental inclusions..."dirt" sifted onto crystal faces during growth) and formation mechanism (embracing minerals that exsolve from an earlier phase on cooling versus overgrowths). There are also liquid inclusions (enhydros in rockhound parlance) that also form in a number of ways...and you can carry the study deeper by looking at the "daughter" minerals that precipitate from the trapped liquids!). There are actually several historic threads on FMF that deal with certain specific included materials...from those leading to general coloration...Prase (green quartz colored by very fine-grained amphibole-pyroxene inclusions; to oriented fine-grained inclusions that create optical effects...Asterism (aligned inclusions in corundum...probably an exsolution phenomenon rather than trapping); to slightly coarser inclusions that can be discriminated with the naked eye that give color and/or optical effects...Strawberry quartz (wispy to whiskery hematite inclusions in quartz...see work by co-moderator John S. White)...to oriented mega-inclusions...your hematite plates and the galena phantoms in fluorite below)...to (apparently) randomly oriented mega inclusions ("psilomelane" in quartz below).

I am really glad you are tapping into this lode...

[Peter Megaw]

Miissed one

[Peter Megaw]

Should have also mentioned John Koivula's exhaustive work on inclusions in quartz...this is a wonderfully and profusely illustrated book

[John S. White]

Elise, the apatite is seen through the quartz, it was not broken to expose the crystals.

Here is another favorite of mine. The black dot is a spherical bubble that is coated by some form of carbon. It moves back and forth about 5 millimeters, and is only about 2 mm in diameter. The quartz crystal is 4.8 cm across.

The locality given to me by the dealer is Zhao Tong, Yunan, China.

[Elise]

[Elise]