FMF - Friends of Minerals Forum, discussion and message board

[MSrockhound]

I was offered this specimen recently and was curious as to how it could have formed, how rare this is, and if this is something I should purchase before its too late. I enjoy having a few atypical specimens and have never seen one like his before, also any insight on this specimen would be appreciated, all I know is that it is afghani in origin.

Cheers,
Chris

[Riccardo Modanesi]

Hi MSRockhound!
This is a typical elbaite from the southern Asian basin (Afghanistan, Pakistan, India etc.). The inclusions are made by growth channels and some fractures. If you see it by a microscope, it's not to exclude you will see some mineral inclusions as well! Sometime mineral inclusions are very nice and interesting!
I hope I was useful for you. Greetings from Italy by Riccardo.

[Ru Smith]

Very interesting specimen.

There is an excellent discussion of these "hollow tourmalines" here:
https://www.minsocam.org/msa/special/pig/PIG_CQ/PIG_CQ_hllw_tur.html
(link normalized by FMF)

[Ru Smith]

The end-on view is not a very clear image, but gives an impression that there is not a simple empty trigonal prism along the axis of the crystal. Perhaps this could be an example of skeletal growth from a highly supersaturated solution as opposed to the selective dissolution mechanisms discussed in the "PIG" thread.

[Josele]

I have a tourmaline, also from Afghanistan, with a similar growing pattern type and some "holes".

And another one from Pakistan that shows a small portion of overlaping exterior layer creating a void space.

Maybe Chris specimen is an extreme example of this growing pattern type.