I wanted to share this with the group. Recently came across this amethyst gemstone and was taken back by the number and type of inclusions/features. Spent a lot of time today trying to get good images and I think I finally got a couple.
The stone was mined near Morogoro, Tanzania. I acquired some of the rough material along with this and one other cut stone.
The vendor called this “Stained Glass Amethyst” 15.2 x 11.1 x 7.6mm 7.96 cts.; emerald cut.
I was about to do identification tests …but didn’t get past the loupe exam before throwing this under the microscope.
I will post additional images of the different types of inclusions …but for now… here are some initial snapshots…
Added dimensions for the bubble. Apologize for the color contrast for the text and dimension arrows. Still learning how to adjust / merge layers in the imaging software.
Will also post my identification test results here as well… just need to break away from looking at this eye-candy zoo!
Completely agree! This one has been entertaining me for quite some time now. And I have yet to do the basic identification tests…
I purchased the AmScope 3.5 - 90X trinocular; SM-2TZ-DK-10M about six months ago. It is not a bad scope for the price. I am writing up a review on it and will post in separate topic.
geology of the area is ultra metamorphic (migmatities, granulite facies) to high grade metamorphic rocks with marbles hosting corundum gems. Amethysts and other pegmatite hosted gems (tourmaline), are present in anatexic pegmatities. Some of the pegmatites are hosted in ultrabasic rock. Aluminum and Magnesium contents are high. Needle inclusions are most likely to be rutile. See if you can determine whether the bubble inclusions are fluid filled or gas and fluid, by foucusing the microscope on them with the same inclusion in a different orientation… it’s a wonderland of inclusions that tell the story of the environment that they grew in.
During the initial loupe exam, I rotated the stone to see if the void in the two-phase inclusion would move, which it did not. Different light fields and incident angles (apologize but didn’t capture images of these views), indicates the void is not fluid-filled, based on the light transmission behavior. (Really could have used the polarizing filter that I didn’t purchase with the instrument).
Will post more images of the rutile and some darker acicular inclusions that might be Tourmaline. A few red colored inclusions near some hematite spheroids that may be Lepidocrocite. There are some colorless negative crystals (hexagonal platelets) possibly quartz. Several surface breaching inclusions are present on a few facets, including a one large one in the lower right side of the table that could be hematite or goethite. (dark spot in the table facing image.) Will be capturing images of that one.
Guess there is some work to do…
The geological indices of the Morogoro area is quite profound!
those inclusions are pretty common in pegmatite hosted quartz. The host rock, as I understand is archean (very ancient) cratonic rock that underwent ultrametamorphism during an ancient continental collision, to the point of incipient melting. Fluids, mostly water, driven out of sedimentary rocks undergoing all grades of metamorphism would carry many incompatible elements including tin, lithium, beryllium, fluoride, titanium, niboium, tantalum, and numerous others that would give rise to gems and their color centers… typical pegmatite minerals including varieties of quartz, tourmaline, topaz, beryls… marbles are stable across mid to high grade metamorphism. Limestones containing aluminum as clays would change into corundum bearing marbles, with marbles being stable across a wide range of metamorphic conditions…rubies are found in the same area… continental collisions occuring in Archean times, 4 to 2.5 billion years ago, would have created the same conditions as the collision with India with Asia, which gave rise to the gem belt stretching from Afghanistan through Myanmar (part of the transHimalayan mountain belt) .the main diffrence being that continental crust has evolved over time to become enriched in incompatibles, large ion lithophiles, sulfur, carbon, phosphate and other elements involved in life processes.
What you have is a nice piece of well colored amethyst. The inclusions, especially rutile which are visible by the naked eye lend addition value as a rutilated amethyst…depending on a collector’s taste. Further pondering of what ALL of the inclusions are may require an expert gemologist or mineralogist. Good luck on figuring out what else is in it. I think you have a very nice stone… congrants on getting it/ And keep me and others up to date on what else you find out about that stone… again, congrants!
It’s pretty amazing. Can you either post or PM me with pics of the back and sides? Also, do you know if the seller found it (ie rock hunted it), and if so, from where?
For what it’s worth, I don’t think it’s a “bubble”, per se, although it may have been natural, it’s been enhanced (notched) intentionally, the whole thing is cut with great care, not randomly . It’s ancient and spectacular.
I will be posting additional images this coming weekend. I have been unfortunately overwhelmed with some work projects keeping me away from “scope time”
