I am having trouble with identifying this crystal shape; five sides. All of these and more I have, have five sides; the top looking like a point which has worn down, one long side, two short sides opposite withe bottom being squared off and flat.
I’ve looked off and on for a while now in my books and on the internet regarding crystal systems, but am very unsure as to which system they belong.
Thank you for any help.
I wish I could help with identifying crystal shape, but I too struggle with this, and Ive come to learn (through comments from other users) it’s likely not knowable for most stones without very expensive and precise equipment/pro analysis with said equipment. Said differently, I don’t believe you can ID crystal shape and use that as an identification vector for most stones (and these in particular). I welcome thoughts on those comments, I may be wrong and would be happy to be wrong, but with the exception of very few, naturally occurring “twinned” or discrete crystal segments that are isolated in space enough that you can see them (magnifies or otherwise), it’s not a feature that can be known and used for identification purposes except in lab situations.
Thank you Paul. That’s all I need.
I have one more immediate problem. I signed up for an account with GIA for gem identification and have been making myself anxious and have vacillated for a week over what I should send, because it’s expensive.
I called this morning only to find out they will not take a rough stone. They have to be facedted and polished. All my stones are polished. That’s how I find out what they really are. However, there are some stones which test positive for what could be fairly valuable (or not) and though I invested in a flat lap machine (Hi-Tech 6 inch; the only one I could swing) because the size of some of these are big and I know very little about faceting, I am giving myself anxiety attacks over just cutting away.
Take these for example:
The big one is 82.5 carats and the other two are 49 or so. Should I just cut them as big as possible? Practically, who would wear a big, huge gemstone and I have no idea how of which angles, etc, are the best. I have been shaving them down, following their natural shape.
So I guess the question is, should I just facet them as big and practical as possible so they could later be cut by someone who knows what they are doing? I hate to ruin anything that big, because you don’t come across it every day.
My hands are tied if I don’t. My favorite jeweler doesn’t facet and bemoans the people he sends his stones to, to be faceted. I am loathe to send something off to someone I don’t know.
I had cancer, now gone, and have so many stones it’s mind boggling and if they are worth anything, I want to set up a trust for my animals and help a few people.
The lady at GIA said they could be cabochons, but they can’t have any rough areas.
The baby blue one has a fracture on each side, which if I polish it down to be even with the other areas, I’m losing a lot (or what I perceive to be a lot) of the gemstone.
Any insight would be appreciated.
I don’t believe any of these are crystals. Just shapes that look pentagonal. There aren’t any known pentagonal crystals.
See: September 26, 2003• Phys. Rev. Focus 12, 10
I am not sure I am qualified to help, but if I had to guess, I’d say they are agate, which is not usually faceted. Agate is also not worth very much, please forgive me for saying, it is not a rare stone but it was coveted for millennia as one of the primary materials in ancient bead making, which means the material had meaning to peoples long ago. That makes them special, in my opinion, but not really valuable monetarily. Personally, I like the shape as is. They are shaped as they are for a reason, and I like that you have maintained that, just polishing it up a bit. I have a bunch of tiny pieces of jade I got on a beach and the elements made them perfect, I would just degrade them if I tried to do anything with them. So personally, I’d stop there, but that’s just me. I hope this is helpful.
Thanks guys. Will keep everyone posted.
The question was more about how much needs to be done for submittal to GIA, so I can begin to whittle down what some of these stones are.
The big, dark, grey-blue one is striking to me because it’s color resembles the tone of gahnospinel or sapphirine.
I keep second guessing myself, which is why I want to send a stone in for identification.
I know agates aren’t worth a lot, though some are. I know more than it seems. It’s been a full time hobby for four years.
I LOVE the shapes they are. However, if I don’t start pinning down what some of them are, it will drive me crazy.
Besides, they are too pretty to sit in cigar boxes.
Ya’ll have a nice day.
I apologise. The first question WAS about crystal habit.
I asked a second question. Probably should have made a seperate topic, but thought it would needlessly clog the system.
Moving on…
Nice Chalcedony specimens you have there. You are having difficulty identifying the “Crystal Habit” or “Crystal Shape” because these would be cryptocrystalline or microcrystalline quartz. These are not large scale mono-crystals as you perceive. At the Unit Cell level they would be Trigonal. No need to send these to the GIA at all. Just take the Specific Gravity and see if it is 2.60 (SG of Chalcedony). You can also polish a small flat and take a Refractive Index and see if it is 1.53 - 1.54 (RI of Chalcedony). I hope this prevents you from “going crazy”. 
Those stones are river rocks. Most of them appear to be quartz stones, crytocrystalline, such as agate, jasper, chalcedony. As such, the crystals are intergrown microscopic crystals. The rough form of each stone does not reflect the underlying cyptocrystalline structure… in other words, the stones have no external crystal structure, which is why they could all be cryptocrystalline quartz occurring in any shape. alluvial stones are waterworn,with even sapphire crystals and alluvial diamonds losing their original external crystal shape and turning into rounded pebbles.
So far a jewelry making out of those kinds of stones, some will have very pretty markings making them desireable for cabochons… They have to be sliced using a diamond bladed rock saw or even a ceramic tile cutter… losing gross carat weight by cutting and polishing stones like this really makes no difference trying to preserve as much gross weight as you can by surface polishing won’t give you as much value compared to slicing them up and making them into cabs.
The smaller ones can be sliced with a trim saw… the larger ones are too bulky and have to be sliced with a slab saw… If you are interested in lapidary and making your own jewelry seriously, investing in rock cutting saws and grinding wheels is the way to go… a couple of nice cabs out of one rock will be worth much more than the whole surface polished rock itself… the advice given by the GIA person is correct. cutting a pebble in half through the center will give you an idea of what is inside…cabs sliced out of the pebble should be without visible cracks, rough areas…by cutting a pebble, you will get an idea of how to cut the rest of it…
Jewerly making and lapidary are value added enterprises… the skilled labor and time it takes to cut attractive gems out of raw material and setting them into jewelry is where most of the value lies… not so much the in raw stones themselves. This is especially true in your case… quartz stones are of little value in and of themselves as they are so abundant. Cut gemstones out of quartz crystals, such as rock crystal, citrine, pale amethyst and smokey quartz, as opposed to cryptocrystalline cabs are more valuable than plain agates… but the price of quartz stones is still low… cut crystalline quartz is worth in the neightborhood of $10/ct…the price hasn’t gone up over years due to their abundance. Agate like stones are worth far less, cabs made out of them go into low end jewelry…worth a few dollars to $10 to $20 per cab finished…the exceptions to that are agates and chalcedony with internal colored growth markings… those are more highly prized… fairburns, lake superior agates, moss agates, picture agates are worth more because of the internal nature made designs.
Thanks m. The varied type, color, patterns, etc. I have is incredible.
I’m working on polishing the small flat needed to get the correct R.I. I was waiting for my new glasses to come in (yesterday) and the stationary, correct wavelength light source I ordered (should be in today) to make sure I get consistent results.
Here’s a couple more.
Have you considered that maybe someone cut up the original specimens into roughly five sided “rough” pieces that were then put into a tumbler and roughly polished.
I know they were not put in a tumbler, because that is how I found them. Because I have so many and they seem to have been chosen for hardness, pattern and color, I hypothesized that some indigenous people may have done that. Because they all came from the same area and river system.
What is also strange is when I would find them, invariably they were found in pairs of the same pattern and color and in what I called “layers”. I would find, let’s say, all the same tone of blue colored stones on the same day. The exact same tone.
It’s just weird. Sometimes they are in threes.
Most seem to have been worked, but many were covered in layers of other stuff I had to patiently sand off to get to the real color and transparency. That’s what made me think they have been through quite a few climate incidences.
They all do look like they were tumbled, But not by me. And since they were found in loads of what we call down here big rock gravel (as opposed to pebbles or in between) I highly doubt someone tumbled them and then threw them into the river system.
I have tons and tons of chalcedony nodules, big and pure, which were already freed from whatever they formed in and all appeared to have been polished at some point, but were filthy.
My first thoughts when I knew nothing about stones, was they looked like old mine tailings. Many look as though there were slight holes drilled into them in order to see what was inside.
I just don’t think it’s random. Just a gut feeling. I handled many ancient dzi, agate and carnelians 20 or so years ago and they have the same feel and look; like they had been worked and handled.
Like this one. I can’t scratch it, it’s hard as heck to work with. You can just grind and grind and very little happens. 9 hardness pencil, stick whatever you call it will not scratch even if I put my
weight into it. It’s pretty big; 13.8 grams.
The inclusions in this thing are amazing. So many different types. Just beautiful.
river rocks are naturally tumbled… sand and gravel and running water do the tumbling… a glossy finish can’t be achieved, even with very find sand being present, the larger particles grind down the surface into a mat or ground glass appearance. same thing happens to beach glass… broken piece of bottles that get tumbled in the sand by waves into smooth shapes with a dull finish… finding every shape is to be expected…
The last one you showed is very hard according to your scratch test. Do you have a diamond tip or a diamond coated knife sharpener?.. should scratch with a knife sharpener… (costs about $12.00 at a hardware store, works far more easier to sharpen knives than hardness 9 aluminum oxide sharpeners… silicon carbide- carborundum grinding wheels and knife sharpeners also should scratch it… hardness is 9.2-9.5)… don’t get your hopes up to high for finding a diamond or corundum stone… corundum stones are dense/heavy and don’t travel very far from their source rocks… source rocks are nowhere close by to Louisiana. Closest place is in Helena MT region… Diamond is out of the question, definitely doesn’t look like diamond… even though they may travel further, there are no diamond bearing sources rocks anywhere near by… closest diamond pipes are in Crater of Diamonds State Park in AR…still a ways off.
You also mentioned finding layers in some of your stones… layers of varying color or different hues of the same color would point to agates/chalcedony… stones like these can be quite tough… they would take a lot of grinding to shape and polish even if starting with a rough carborundum wheel…finer grit sizes take a long time to grind and polish.
You still have a good collection of stones… some will be very pretty, especially the ligher colored translucent ones when made into cabs.
Sorry, I misinterpreted what you meant by layers… similar rock types and similar sizes will setlle out in layers in alluvial deposits… running water sorts them by weight…floods will jumbled them up, resorting happens when normal water flow resumes…cycles of flooding and low water will eventually sort them out.
You are correct sir!.. 5 fold symmetry is quasi crystalline, doesn’t have translational or long range symmetry. Dodecahedrons are cubic, with garnet typically taking that form… subset of icosahedrons, but not 5 fold symmetric. The article you cited is of interest… thanks for the reference.
I’m still working on getting a flat, polished surface on the last one to get an RI reading. I really need the light source I ordered. It’s not coming till the 23rd.
The correct RI on any of these stones will narrow them down in short order.
What’s interesting is I was told there have been diamonds found. I don’t have any.
One point I want to emphasize is the possibility some of these stones arrived here via human transport. This area was a convergence point for quite a few indigenous tribes.
And there is that extinct volcano. Door Point Volcano - Wikipedia
And this one.
https://www.nationalgeographic.com/culture/article/new-seafloor-map-gulf-of-mexico
And this one talks about impact breccia in the Gulf of Mexico which I have some lovely pieces of.
As always, thank you for the educated and thoughtful input. I have worked with these stones for about 4 years and it just gets more and more interesting.
The last stone looks like a garnet but I won’t know until I get a definitive RI reading, which I am still working on.
I just remembered something I read in an abstract some time ago.
When archaeologists excavated one of the many native american mounds here in Louisiana, they found, I believe, hundreds of tools used for working stone.
However, they found not one stone. What happened to the stones?
I’ll see if I can find that after I’ve had my coffee.
