Crystal Shape Capitulation

Gem Related Discussion
1

I posted once before, and have seen several posts by other members, related to identifying crystal shape and crystal shape as a diagnostic tool. I have never been successful either ID’g all but the most explicit (eg., “tower” like single mineral elongated) or using them in any way for diagnostic proposes. I do understand that using UV filter the habit can sometimes be inferred, but I’ve had little luck with that, on the whole, as well.

I have pretty much concluded that I have misunderstood the idea that crystal form can be any of those things (ID’d, or used as a diagnostic input, except very crudely and inaccurately). Yesterday I looked through over 20 random examples, clearly visible (with the naked eye, so best case examples) to see if I could clearly ID any given crystal shape. No matter the magnification level, lighting, angle, amount of wine I drank, etc., I could not clearly ID a single one. There were a few where a very rough recurrence of some specific shape existed, but the exceptions to that shape on the same stone way outnumbered the recurring ones. Additionally, even within known crystal shapes, I have many exceptional stones with do not match the reference shape, which is well understood to be the case (as I get it).

I guess this is more to sanity check whether i’m missing anything. I ran it past ChatGPT (the forum of first/last resort when confronted with headscratchers like this), and it too confirmed they are neither diagnostic or generally identifiable except in lab conditions with very powerful, active (ie, more than optical) microscopes, and even then, not really diagnostic due to number of exceptions generally occurring.

Sorry if I am stating the obvious, but again, I’ve seen about interest on this topic (usually going unanswered) that I figured this may be helpful to others banging their head against the wall trying to see what is very hard/impossible to practical/essentially unknowable.

Thoughts?

Happy to share many pics I took of magnifies stones, if anyone wants tk take a run and pointing out what I’m missing. Here are a few examples:

IMG_4955
IMG_49551170×2532 442 KB

IMG_4954
IMG_49541170×2532 509 KB

IMG_4945
IMG_49451170×2532 427 KB

IMG_4946
IMG_49461170×2532 472 KB

IMG_4944
IMG_49441170×2532 410 KB

2

Hi Paul,

I was doing some resource gathering in the background to respond to a previous conversation we were in. The topic had a tangent discussion identifying the crystal habit while in-situ of the host matrix. You had asked some really good questions on the subject and I felt obligated to provide some resources to help with knowledge/examples of these identification processes.

Apologize for not being quicker with this information. I hadn’t forgotten to follow-up, but time has been rather twisted with some very successful and some not so successful work tasks the past few weeks. It has been busy, nonetheless.

Identifying a crystal habit is not keenly straight-forward for those who are not in the appropriate disciplines, focused on such puzzles (Ahem…speaking strictly about myself here… as I still struggle with the nomenclature). Not sure how familiar you are with crystallography in general, so I am posting several levels of resources for the subject. I have these book-marked on “speed-dial” :slight_smile:

My “go-to” resources:

Open Mineralogy Chapters 10, 11, and 13 focus on Crystal Habit and structures.

Optical Mineralogy

Open Petrology

Mineral Identification Key II Site This is the host site for the link below.

Generalized Habit descriptors A good rule of thumb process to practice in field collecting.

Cheers!

3 Likes
3

Thank you, sir, this is very helpful. I was in that zone where one feels like they might be missing the obvious but in this case, it seems it’s not so obvious. I went deep on this subject one night and still came up blank so it seems to me (here’s where I get in trouble) it’s not a precise science, but more like a species taxonomy in a ‘tree of life’. In other words, if it lives, it has the same base DNA code, the differences in classification are somewhat fluid; that which works for descriptive, working purpose, because having some sort of classification and categorization is better than none at all, but it is not hard and fast, more utilitarian than empirical. If I got this right, that’s cool by me, and I think I get it, so thanks!

4

unless you have a free large euhedral crystal, it’s pretty hard ID the crystal shape… also impossible where your specimen is an intergrown mass of small crystals. If you already know what the mineral is, finding the crystal shape is easier… but that’s the reverse of the problem that we all have trying to ID the mineral from the crystal shape.

2 Likes
5

Here’s one example of a crystal class with many minerals belonging to it. Even if you can identify the crystal shape, there’s many minerals that belong in that crystal calss.

Hexagonal Crystal System Explained: Gemologist vs Geologist
[image]
YouTube · Gemstones
34K+ views · 5 years ago
(https://www.youtube.com/watch?v=15e6kjwyk90)

2 Likes
6

Wow, these are great links, thank you so much. I imagine it will also become my go to resource.