FMF - Friends of Minerals Forum, discussion and message board

[Michael Shaw]

Hello Pierre,

Yes, the terminations are pretty unusual for schorl. I have an elbaite from Brazil that has similar steep pyramidal terminations, but I'm pretty certain that these are schorl. They are completely opaque black, even at their thinnest point. The dealer told me he acquired these on his last trip there and that he had not seen similar specimens previously. I would love to know what conditions caused these unusual terminations.

Michael

[Jordi Fabre]

[Roger Warin]

Michael,
It is difficult to determine. The material deposition is kinetically controlled, fast or slow. The temperature, the concentration of ions at the local level, the presence of foreign ligands in competition, etc. are factors that control crystallization.
A simple example, look at the difference or a equant or skeletal quartz crystal.
Roger.

[John S. White]

I was fortunate to have acquired this pair about 12 years ago. The locality given was Laila Base Camp, Dazu, Skardu, Pakistan. Jeff Scovil photo.

[Pierre Joubert]

I think John's description 'pencil habit' is very apt. Surely this is a seperate variety, something like foitite? Congratulations with your fine specimen Michael.

[Michael Shaw]

Thank you all for the input. Clearly these "pencil habit" schorls have been around much longer than I had thought. I had never seen them before, so I assumed they were something new. As to the exact locality, the specimens belonging to Carles and John both mentioned Laila Peak, so these are no doubt from the same general vicinity, perhaps from the same prospect.

Michael

[Michael Shaw]

Continuing with minerals from Pakistan.

[Michael Shaw]

Continuing with minerals from Pakistan.

[Tobi]

Wonderful elbaite ( https://www.mineral-forum.com/message-board/files/654_elbaite_181.jpg ), Michael!

[Roger Warin]

Hi Michael,
Always pleasant to contemplate. Congratulations.
How can we say that tourmaline "Elbaite-jpg 654" is an elbaite? It seems to contain iron.
Roger.

[Michael Shaw]

[Roger Warin]

Many thanks Michael.
Roger.

[Jordi Fabre]

[Michael Shaw]

With today's post, I will finish showing our collection of specimens from Pakistan. Next up will be a country with a seemingly inexhaustible supply of minerals - China.

[Michael Shaw]

While I am gathering photos and info for the next installment which will feature China, I decided to show this little aquamarine which I recently acquired at the Denver Show. I have never been very successful in being able to photograph gem crystals, showing their transparency, so I spent some time experimenting with some different lighting arrangements until I came up with the image below. I'm pretty happy with the result, and I think I learned quite a bit about the best way to light these kinds of specimens.

Michael