Going crazy trying to find this answer...!!!

[Bling Bling Brodie]

Hello all you wonderful diamond wizz-kids out there. I am currently studying a diploma of diamond technology in Australia (I''m a fellow of the Gemmological Association of Australia) and have this really tricky assignment question that I just can''t seem to get a straight answer for anywhere.

I was hoping someone here may be able to help me. The question is "In regards to diamond as an inclusion in diamond, give the following: (i) possible crystal morphology, and (ii) orientation of the included diamond".

If anyone would answer this question or post a link to some resources this would be very much appreciated!

Cheers from down under

 

[lisa1.01fvs1]

The question is ''In regards to diamond as an inclusion in diamond, give the following: (i) possible crystal morphology, and (ii) orientation of the included diamond''.

OK I''ll take a stab....first I''m not sure of the context of the question at hand: if the inclusion is a "natural?" then #1 would entail a lengthy discussion on the properties of the inclusion and the way/s in which it comes to be (morphology) including chemical makeup and evolution.

Orientation of the natural would speak to the effect such inclusion would present to the appearance and other qualities of the diamond. Additionally another reference to morphology of orientation might be in order as well since this might have a bearing on the type of inclusion and how/why/what to expect from its presence.

I''d search, search, the web and implore, implore strmrdr, cut nut, old miner, etc. to help out on resources.

Sorry for this lame layman''s attempt.

 

[strmrdr]

hmmm a diamond becomes an inclusion in another diamond when it stops growing and another diamond grows around it.


Since diamond inclusions can be present as crystals, needles, clouds and pinpoints I don''t see a common orientation.

 

[diagem]

Date: 3/5/2008 12:35:59 AM
Author:Bling Bling Brodie
Hello all you wonderful diamond wizz-kids out there. I am currently studying a diploma of diamond technology in Australia (I''m a fellow of the Gemmological Association of Australia) and have this really tricky assignment question that I just can''t seem to get a straight answer for anywhere.

I was hoping someone here may be able to help me. The question is ''In regards to diamond as an inclusion in diamond, give the following: (i) possible crystal morphology, and (ii) orientation of the included diamond''.

If anyone would answer this question or post a link to some resources this would be very much appreciated!

Cheers from down under

Sounds to me like both can be correct..., (if I understand the question...??)

A crystal morphology can be easily a Diamond crystalline structure or morphology...
But could easily be a orientation of the included Diamond itself...
What storm is saying sounds like a "macle" type Diamond:
A twinned Diamond crystal. But the crystalline structure of a macle is mirrored (opposite). The mixture or border of the twins are easily included and may mix!
Thats why it is usually an extremely hard task to find a grain direction for cutting purposes..., not to mention polishing...

 

[Angara]

Diamond has perhaps the most interesting crystal morphology of any mineral. Diamonds crystallize as octahedrons (8 sided triangular shape), cubes (6 faced square shape), or dodecahedrons (12 faced geometrical shape) and commonly contain two or more of these forms. Diamonds are formed deep within the earth’s mantle. The journey of a diamond from its cradle in the earth’s mantle to the surface of the earth is a violent transition of the stone from one pressure zone to another. This transition makes the diamond crystal unstable and it begins to dissolve, leaving the surface of many diamonds etched or pitted and the overall shape occasionally rounded. Etched diamonds sometimes exhibit a cross figure on its faces. This process often creates a new crystal form - hexoctahedron (six faces on each of the octahedral faces). Another interesting feature is the etched pits found on the faces / sides of the diamond. Since these are frequently triangular, these etched pits are called trigons. The face of an octahedron is a triangle. Trigons found on octahedrons are oriented such that the point of its triangle is pointed in the opposite direction of point of the triangle of the octahedral face.

The most common geological setting of diamonds is in diamond pipes, small diameter volcanic features. The volcanic host rock is called Kimberlite, whose magma type is generated deep within the earth’s mantle. Diamonds are found, but not formed, in Kimberlite. In nature, diamond forms at temperatures over 1200˚ C (2200˚ F) and at pressures 44,000 times that of atmospheric pressure. These conditions are found only at depths of 100 miles below the earth’s surface. The two main rock types in which diamond is formed are Harzburgite and Eclogite, both being rare Igneous rock types. Harzburgite is composed of olivine, Bronzite (an orthopyroxene), and some Pyrope (chrome- and magnesium-rich varieties); these often being the inclusions in Harzburgitic diamonds. Eclogite is a high pressure metamorphic rock composed of garnet (almandine-Pyrope variety) and Omphacite (a sodium-rich Clinopyroxene. An extremely interesting mineral inclusion that occurs in Eclogite is diamond inclusions in garnet. Kimberlite is then derived from melt of Eclogite or Harzburgite and occasionally contains inclusions of these diamond source rocks.


Hope this helps.

 

[Garry H (Cut Nut)]

Date: 3/5/2008 12:35:59 AM
Author:Bling Bling Brodie
Hello all you wonderful diamond wizz-kids out there. I am currently studying a diploma of diamond technology in Australia (I''m a fellow of the Gemmological Association of Australia) and have this really tricky assignment question that I just can''t seem to get a straight answer for anywhere.

I was hoping someone here may be able to help me. The question is ''In regards to diamond as an inclusion in diamond, give the following: (i) possible crystal morphology, and (ii) orientation of the included diamond''.

If anyone would answer this question or post a link to some resources this would be very much appreciated!

Cheers from down under

Lots of interesting comments, but no answers!

I have helped set these exams and find such questins totally irrelevant. Firstly such inclusions are very rare. When present they are almost impossible to see (same RI).

If you hapened to find one then it would show octahedral or some other obvious diamond morphology (if it did not then you would never pick it as diamond. Duhh! )

I imagine (dont know, but guess) the crystal inclusion would be aligned with the host because
1. it would otherwise get crushed to oblivion and we would never see it
2. the pressure and growth environ would likely be the same and the orientation would be the same.

Crystals tend to grow much faster than most people think.
)

 

[Cleo]

I''m no expert (just A-level Physics & Chemistry) - but I was wondering if the crystalline structure of the first diamond (the inclusion) would influence the orientation of the second (main) diamond. Maybe the orientation of the covalent bonds or something, that would make the main diamond form in the same orientation as the first.

*shrugs* Just guessing really!

I know if you''ve ever used a kids crystal growing kit to grow ''seed'' crystals from saturated solutions, and then dangle one of the seed crystals into a fresh solution, the crystal which grows retains the exact shape of the original... same morphology & orientation.

I realise that diamonds don''t grow from saturated solutions.. but maybe theres something kind of similar which might happen?

I hope you get some answers - and do let us know what you find out!

x x x

 

[Garry H (Cut Nut)]

Date: 3/5/2008 9:56:10 AM
Author: Cleo
I''m no expert (just A-level Physics & Chemistry) - but I was wondering if the crystalline structure of the first diamond (the inclusion) would influence the orientation of the second (main) diamond. Maybe the orientation of the covalent bonds or something, that would make the main diamond form in the same orientation as the first.

*shrugs* Just guessing really!

I know if you''ve ever used a kids crystal growing kit to grow ''seed'' crystals from saturated solutions, and then dangle one of the seed crystals into a fresh solution, the crystal which grows retains the exact shape of the original... same morphology & orientation.

I realise that diamonds don''t grow from saturated solutions.. but maybe theres something kind of similar which might happen?

I hope you get some answers - and do let us know what you find out!

x x x

That is true when the first crystal is the seed for the second, but when two crsytals grow nearby and one overtakes the other, it need not be true.