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Identity HelpGoshenite or clear topaz?

12th Aug 2018 01:49 UTCTheodore Hansen Theo

What types of fractures or cleavage would a chunk of clear topaz or goshenite have? I have a piece of what I am thinking is now goshenite but maybe clear topaz at 730cts weight!

12th Aug 2018 01:55 UTCTheodore Hansen Theo

-- moved topic --

12th Aug 2018 01:57 UTCWayne Corwin

Goshenite has no cleavage, its like quartz.

A photo might help.

13th Aug 2018 22:16 UTCEd Clopton 🌟 Expert

You can check specific gravity, too: 2.7-2.9 for beryl, 3.4-3.6 for topaz.

13th Aug 2018 23:04 UTCOwen Lewis

Why does it have to be one or the other of those two and not something else entirely?

If its topaz and 3/4 kg, it's almost certainly got to be showing at least one or two distinct basal cleavage. There are also going to be some negative crystal inclusions, one, two or three phase, these are likely to be in strings at 90 deg to the basal cleavage (i.e. parallel to the c-axis). Topaz has a much higher lustre than beryl..

If your piece is either of these minerals and is of gem quality it's going to have significant value. So get it properly tested.

14th Aug 2018 00:03 UTCRuss Rizzo Expert

I believe he said 730 carats. Which, unless my math is off, equals 146 grams or roughly 1/7^th of a kilo.

14th Aug 2018 11:43 UTCKeith Compton 🌟 Manager

It might even be a lump of quartz for all we know

14th Aug 2018 13:00 UTCHarold Moritz 🌟 Expert

Quartz has cleavage!! They may be poor to indistinct but they exist.

But they are not as good as topaz's perfect cleavage across the c axis.

If it is a pure specimen then you can ID it via its specific gravity.

14th Aug 2018 13:35 UTCKeith Compton 🌟 Manager

Harold

Harold, it sounds like Theodore is not sure whether his lump has cleavage or fractures, so we don't know either, which is why I mentioned that it could even be a lump of quarz.

As Wayne mentioned - a photo would help.

Theodore says he has a chunk of clear stuff. Hasn't provided a photo, obviously hasn't carried out any tests on it. If it is a clear chunk, and it probably has no matrix then it would be a simple excercise to carry out an spg test. He just has to follow any of the other threads on Specific gravity or Don Pecks SP article.

More speculation at this point all seems a waste of our time.

14th Aug 2018 14:23 UTCOwen Lewis

Russ Rizzo Wrote:

-------------------------------------------------------

> I believe he said 730 carats. Which, unless my

> math is off, equals 146 grams or roughly 1/7th of

> a kilo.

Thank you. Old eyes and jumping to an assumption as rough weights are most frequently quoted in grams :-( Even so, a 730 ct piece of topaz rough of decent quality and you'd be looking at $xxxx or so. Not necessarily so for goshenite, for which there is is no general gem market and even collectors' interest is slight, though small goshenite crystals with interesting inclusions usually sell readily.

14th Aug 2018 15:01 UTCOwen Lewis

Harold Moritz Wrote:

-------------------------------------------------------

> Quartz has cleavage!! They may be poor to

> indistinct but they exist.

> But they are not as good as topaz's perfect

> cleavage across the c axis.

Well, let's just say that there are eminences that would disagree and say that quartz shows no cleavage. Me? I have never yet seen a cleavage plane in quartz but I'm always willing to learn. If anyone reading this either has some convincing photography or else a drawing of sufficient adjacent SiO2 molecules to show the a plane of weakness sufficient to cause cleavage and would like to post one of both in a fresh thread, I'd look with serious interest.

> If it is a pure specimen [Topaz] then you can ID it via

> its specific gravity.

You can distinguish topaz from rough diamond by SG alone? Really? Be advised that there are swindlers making money from those who think this way, from the skillful cutting of topaz rough (of the same SG as diamond) to imitate diamond crystals. And the 'marks' in these swindles were not uneducated members of the general public but were diamond traders, sufficiently experienced (and lazy) as to be confident that they could always tell a diamond crystal just from its appearance and by its 'heft', heft being the sensation felt by bouncing crystals in the palm of the hand (relates directly to mass which, with the appearance of volume relates directly to SD/SG .

14th Aug 2018 18:30 UTCScott Rider

Sorry Theo, asking us to identify stuff without images won't give you clear answers... Plus, you didn't provide any further info, like specific gravity, a hardness test, etc. -- so the guesses we make will not help identify anything... Its like asking someone to identify a Rembrandt painting, without images or a good description...

Theo, how about looking at this: https://www.mindat.org/mesg-11-33466.html

Honestly, I almost think we should stop trying to answer these questions until the poster goes through the above link and follow the guidelines... What I'm saying is the next person who posts after the identity request should direct the inquisitor the link above especially if they did not provide images (who doesn't have a camera these days...) We cannot give educated guesses or even answers (usually) with a paragraph description!! But that's my 2 cents on this...

14th Aug 2018 18:36 UTCScott Rider

Sorry to sound a little demeaning, but I see so many ID requests where the poster may or may not put in an image, but they RARELY go through the procedures lined out in the link below. Many do not put very little efforts to try to find out what they have except maybe a pic or two.

I honestly wasn't trying to sound like a jerk (which it kind of came out like that)... But its just weird to get a request to ID something with NO IMAGES.... Like asking what kind of dog I have and all I provide is the weight and no pictures...... Yeah, maybe if I said I have a 50 pound dog, it'll narrow it down a bit, but still, there are many types of canines that are at that weight...

https://www.mindat.org/mesg-11-33466.html

Maybe I'll just stop looking at ID requests... I almost never answer them anyway as usually someone beats me to the punch, or its a rock and has no interest to me, or, like this one, no images, no tests, nothing other than what the poster thinks they have... Maybe I just woke up on the wrong side of the bed... ; )

14th Aug 2018 19:45 UTCAlfredo Petrov Manager

To be fair to Theo, he wasn't actually asking for an ID, he was just asking what kind of cleavage and fracture topaz and goshenite have so that he could try to ID the rock by himself. In that case no photo is required. A short lecture on how to tell the difference between cleavage and fracture, and their different types, would be sufficient response. If anyone has aready written a Mindat article on that topic, we could just refer Theo to a link to the article. If not, "someone" (not me ;)) ) should write one.

14th Aug 2018 20:18 UTCReiner Mielke Expert

While at it, parting also needs to be considered.

14th Aug 2018 20:33 UTCScott Rider

You're right, he didn't directly ask for an ID, but he did indirectly... And because of that, his question wouldn't necessarily need an image. So for that I apologize.

However, he did say he had a stone so having images would have made this inquiry much easier. And I think he does not need to test things under the context of his question. But, he's definitely trying to find answers about his stone so images and testing would have given the answer he was looking for instead of everyone trying to get more info from him. Also, he didn't respond either which I find a common thing with inquisitors...

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