Does anyone know what type of gemstone this is? Does anyone know if it has any sort of historical relevance?
Thanks
It looks like a dark blue quartz. How would we know if the crystal in the picture was historically significant? It’s not like it’s the hope diamond.
I know. I couldn’t agree with you more. But I’ve been challenged to find out what it is… and so I supposed that it might be something like a gemstone from some old crown or something to that extent.
I’d say blue quartz, also.
I can’t remember its name, but there’s an utility allowing to search for identical pictures on the internet. Maybe you could use such a thing to find a site with the picture properly described?
Is it called TinEye? I tried using it and, I quote:
“0 Results. Searched over 1.8627 billion images.”
So, is the picture all you have? It’s going to be hard to identify any mineral from a single picture. Do you know the scale? Given the size of the fractures, I would guess that this is not a very big crystal, but I do not know that.
What I can observe is that the color varies from turquoise to darker blue; the crystal itself consists of a roughly hexagonal prism with two roughly hexagonal pyramids on the ends. The fracture may be conchoidal, judging from the upper left of the photo, but the rightmost face of the prism might show perfect cleavage. It would be nice to have a better perspective of the crystal structure, certainly a top view, as well as some measurements of the hardness, density and optical properties.
Now the reasonable thing seems to be to go through a list of minerals which can be blue and are members of the hexagonal crystal system, or could pass for it at first glance.
Corundum (sapphire)-- Certainly a member of the hexagonal crystal system, but the crystals tend to be more bipyramidal or barrel-shaped.
Beryl (aquamarine)-- Also in the hexagonal crystal system, but the crystals tend to be long prisms.
Quartz-- Others have suggested it, but I am very doubtful. I have never seen quartz crystals of that color, for starters. Also, the crystal form does not match. The mystery mineral has six-fold symmetry, while quartz has only three-fold symmetry. Here is a page of mineral data for quartz. Notice on the crystal form, how the faces adjacent faces of the prism are offset from each other, and how adjacent faces of the pyramids are of different sizes, unlike our mineral. This cannot be quartz, if I am interpreting the picture correctly.
Apatite-- I think this is it. It is a member of the hexagonal - dipyramidal crystal system, and can and does form crystals that look like this one, see for instance here, and even in that shade of blue. It also shows conchoidal fracture, like our specimen. More mineral data on apatite here. Apatite is not a common gem mineral due to its relative softness, but forms nice crystals nonetheless.
So, my guess is apatite, but if you have more information, I would love to hear it, and might end up revising my guess.
Wow. Thank you very much for your help! Unfortunately, this is the only image I have. I will take a look into apatite and hope that the answer is correct. If not, I shall return here and post any new findings.
Thanks again.
Sure! Also, you shouldn’t snack right before working on this problem-- don’t want to lose your apatite!
snort
Hahaha! By the way, you are right. It is, indeed, apatite.
Thanks for your help.
M
As far as historical significance, are there any “crown jewels” that contain uncut stones like this?
This looks more like something you would buy at a gem show and put on your desk.
The blue color is a perfect match for a Potassium Bromide crystal with Color Centers in it. Even the variation in intensity matches what a color center crystal looks like.
Color Centers are point defects in crystals that give it coloration. Potassium Chloride is purplish and Lithium Fluoride with color centers is yellow, but KBr, which is normally transparent, turns a beautiful blue when it has these defects present. (It’s not due to impurities, either – the crystal is pure KBr, but the structure of the defects absorbs red light and makes it appear blue).
Unfortunately, it almost certainly isn’t a KBr crystal – Potassium Bromide is a Face-Centered Cubic structure, and its cleavage planes, like those of table salt, tend to make it produce a cubic crystal. You could cleave it into a different shape, or grind it that way, but I doubt if anyone went to that much trouble.
I think faceting of stones was invented in Renaissance Italy. Therefore, any earlier crown jewels would be polished but still “uncut.” Check out the Black Prince’s Ruby–the big red blob on the front of the Imperial State Crown. (And it’s not a ruby.)
Then, there’s the Iron Crown of Lombardy…
