August 24:—SAN ANTONIO, TEXAS: Retail show; Southwest Gem and Mineral Society of San Antonio; Sat. 10-5
Welcome to the GemologyOnline.com Forum
A non-profit Forum for the exchange of gemological ideas
It is currently Sat Aug 24, 2019 11:58 am

All times are UTC - 4 hours




Post new topic Reply to topic  [ 2 posts ] 
Author Message
 Post subject: The most unusual inclusion I met - natural crankshaft!
PostPosted: Mon Feb 16, 2015 5:00 pm 
Offline
Valued Contributor

Joined: Wed Feb 11, 2015 5:22 pm
Posts: 170
Location: Lachine, Quebec
I will keep posting pictures of gems and inclusions in the "[url]Usual and unusual gemstones and inclusions[/url]", but in this stone I found inclusions I never saw before and after, and I could not find anything like that in any source and book.

All story is about this stone:

Image

I got it as cheap included tanzanite but from unknown source so I tested it myself. there are records from my lab journal:

RI: 1.694 - 1.703, 1.698 - 1.706, 1.694 - 1.704, 1.699 - 1.706
SG: 3.37
Polariscope: anisotropic
Optic sign: don't see anything in conoscope; calculation B+
Dichroscope: 3 colors, violet, blue, greenish-grey
Suggestion: Zoisite (Tanzanite)

Color is very low saturated violetish blue, heavily included. Inclusions are very well visible by naked eye and have appearance like an thick needles or tubes.

Then I put stone under microscope and from this moment I could not close my mouth long enough. All pictures has been taken under reflected light.

Mixed light, 40x, FoV 6.05 mm:
Image

Mixed light, 80x, FoV 3.00 mm:
Image

Mixed light, 80x, FoV 3.00 mm:
Image

Same image just cropped to focus on the main object, FoV 1.60 mm
Image

When I saw this "constructions" first thought came up to my mind was "What such perfectly shaped crankshaft is doing inside of stone!".

All of this inclusions were observed under table of stone, no one had reached the surface. But looking on the pavilion I found one very small piece of crankshaft reaching surface of one of facets:

Mixed light, 200x, FoV 1.14 mm:
Image

Under highest magnification on my microscope 320x, after long play with additional lighting I was able to see the surface of this cylinder itself, and the surface looked grainy. Next my step was fixing of micro-surgical ophthalmologist's needle (I had it from my friend) in feather of my cockatoo Kony, feather I wanted to use as holder for needle. After-all I was lucky to see under microscope how very thick and raf, not really well sharped needs still scratches the black substance of the inclusion.

My though was that this inclusion is graphite. The only I had no idea how it is possible for graphite to format such an "crankshaft".

With this problem I got help from one of Russian scientists, he is actually expert in the field of physics of crystals. Here is short second translation of his explanation (first translation was from Russian scientific to Russian normal).

Graphite is usually crystallizes in the form of flat tabular crystals (such as hematite). Flat crystals are forming a tightly packed layered packages. Tightly packed, but not tightly compressed - individual plate-like crystals of graphite have no contact with each other (otherwise they would simply diffused into each other) and forming a layered structure. Between the layers is still the tiny-tiny layer of emptiness. Here in this space during the formation of the package are being integrated some single atoms, not included in crystal structure. Atoms might be off different elements from hydrogen to carbon itself. Most often - boron atoms. These atoms, embedded between layers, create additional stress Which causes flat packages to bend and twist. As larger the diameter of atoms, embedded between layers, and as more of them quantitatively, as tighter the twist occurs.

There are known some forms of graphite crystals in the form of cylinders and spheres, but all these cases are known as examples of "wrong" nucleation as independent structures, as mineral species. As inclusions in minerals graphite is also well known, but, judging by the reviews of all found publications and references... I can say I did not find anything. Maybe I was just looking not careful enough.

Would be good to have some replies if some knows about such graphite inclusions, saw that or read about, so it will be а good proof that I am right. Or - I am not right... :)


Last edited by GSK on Thu May 28, 2015 2:20 pm, edited 12 times in total.

Top
 Profile  
Reply with quote  
 Post subject: Re: The most unusual inclusion I met - natural crankshaft!
PostPosted: Tue Mar 03, 2015 9:21 am 
Offline
Gemology Online Veteran
User avatar

Joined: Fri Jul 04, 2014 8:17 pm
Posts: 614
Location: Halifax, Nova Scotia, Canada
Awesome :D


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 2 posts ] 

All times are UTC - 4 hours


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group
Gemology Style ported to phpBB3 by Christian Bullock