Topaz, or not topaz. That is the question..?

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G'day AtomRat, cleavage and fracture can be a pain to figure out when starting off. Still getting the hang of it all myself.
Here is something that may help it make a bit more sense:
http://academic.brooklyn.cuny.edu/geology/grocha/mineral/cleavage.html http://www.minerals.net/resource/property/cleavage_fracture_parting.aspx
[video=480,360]https://www.youtube.com/watch?v=GOVgOxRAkO0[/video]

In the next link, about halfway down the page is an example of topaz cleavage in a pit of a tumbled white topaz http://aussielapidaryforum.com/forum/index.php?topic=1804.0

Internet comments can be a fickle thing, they can easily be read wrongly or misconstrued but some are just not nice :mad: ;) :p
 
After a bit of pain I think the gears clicked over. If what I'm thinking is correct, that big topaz in solomans hand could have been massive(er) in height? And its at risk of breaking along those two lines / dimples along the left side so a line is drawn across that front plane to prevent breakage when cutting..?
 
Most of the topaz I've found has come from Mount Gibson and is still in its original crystal shape so there's no problem-telling Where the cleavage plane lies.

Dads next door neighbour showed me a nice big stream worn piece the other week. Nothing remained of the crystal shape but on careful examination I was able to find a crack running through it that was not so much a crack but an absolutely perfectly straight fracture line, with a smaller one just like it running dead parallel to the first.

See if you can see any feature like that AtomRat, they don't look like ordinary cracks which wander randomly about the place.
 
Lefty said:
Dunno if it's fact or crap but I read somewhere that in the old days a lot of gold prospectors used exactly that approach. If they found a transparent stone while digging, they would put it on an anvil and bash it with a hammer :eek: - a gemstone was so hard it would not break so if it broke it was not a gemstone.

My eyes water thinking about all the beautiful stones that must have been pulverised during a test that none could possibly pass 8.(
Click to expand...

I read a similar article somwhere Lefty about an old timer hitting a very large Diamond on an anvil with a hammer, it smashed and was identified from the I think 30ct that remained. Must have been a good size if 30ct was left.........
 
well ive certainly been told all the info I need to know about it all, so ill just keep searching.

Instead of weighing individual rocks, ill sg test all in one go in a bucket. if it comes up near 2.7 I know I got no topaz at all
 
Heatho said:
Lefty said:
Dunno if it's fact or crap but I read somewhere that in the old days a lot of gold prospectors used exactly that approach. If they found a transparent stone while digging, they would put it on an anvil and bash it with a hammer :eek: - a gemstone was so hard it would not break so if it broke it was not a gemstone.

My eyes water thinking about all the beautiful stones that must have been pulverised during a test that none could possibly pass 8.(
Click to expand...

I read a similar article somwhere Lefty about an old timer hitting a very large Diamond on an anvil with a hammer, it smashed and was identified from the I think 30ct that remained. Must have been a good size if 30ct was left.........
Click to expand...

Wouldn't you just kick your own arse until your dying day? :eek: :)
 
I should mention that I was hitting it not to test for hardness, I was looking for the perfect basal cleavage of what I thought may have been a topaz using a knife and mallet.

I know its not reccomended but im sure happy to destroy one to identify a million others, as long as that one doesnt look too special. ( the one I smashed looked like a pretty standard clear quartz with no gleam )

..i still wonder though why the old timers didnt want the gems or find them "pretty" like gold. Its not like gemstones were not known to be precious at the time as rulers always had them for decoration.

Did they not have a value? I find that still hard to believe as the same statement I wrote above.

For quartz it does make sense, theres a lot of it but it could have still been used.
 
Anyway, back to the topaz on topic. I attempted the SG test with all my rocks in one go and it failed. Definately need accurate scales as I weighed 200g of rock and its SG came up as 1.0, somethings up with that considering its all quartz ( probably ) so ill go back to weighing individual rocks. I do have a bit of a faster process going on
 
I do not think weighing rocks in bulk for a SG test would be a good idea as SG can differ in specimens, or varieties of the same mineral, due to ionic substitution.
I believe this would lead from a small deviation from sample to sample when measured individually, to a much larger inaccuracy when measured in bulk. But i could be wrong.
 
Hey AtomRat,

Most waterworn topaz will have fractures, and they become easy to spot as they are on a flat plane. If you have trouble seeing into stones, something like Refractol might help. Aussiesapphire carry it but are currently out of stock. I think Methyl salicylate and aniseed oil are pretty close but I've had trouble finding supplies of the pure product.

Cheers
 
Mfdes - Can you explain this a bit better mate? I've looked up expensive refratometers and I don't have the budget for them. I don't know about the mini chromatic lighting either and how it works. I barely know refraction so it will need to be explained or I'll search it up. I can find the latter from local brewing supplies.

Can a beer / sugar refractometer be used as a crude device? They are cheap and run off some sort of index. But as were talking gemstones, I know its not something you want to deal with cheaply..

shivan - I got the idea from Google searches and people using large machines doing bulk weights. I wasn't after an exact number, I was hoping for a 2.6-2.7 SG to show up, but the 1.1 meant the innacuracy of my cooking scales wrecked it I think. I was hoping, IG there were a topaz, the total SG would be closer to 3 and then I was going to find the topaz by elimination. Fail again hehe at least I'm tryin! :lol:
 
I see, cheers for the link and refracto info. Are you more saying it can be used to find cleavage though? I'll try it out anyway on a clear quartz.

My issue is I have buckets of clear quartz and just trying to pick out the possible topaz is hard enough. In all honesty, I don't think I have a single one yet but I am trying not to think that. The creeks here have high possibility of holding them
 
AtomRat said:
I see, cheers for the link and refracto info. Are you more saying it can be used to find cleavage though? I'll try it out anyway on a clear quartz.

My issue is I have buckets of clear quartz and just trying to pick out the possible topaz is hard enough. In all honesty, I don't think I have a single one yet but I am trying not to think that. The creeks here have high possibility of holding them
Click to expand...

I just put an image up the other day in the lapidary forum. A topaz in refractol (not sure how to use this tablet for links). Shows flaws and probable cleavage plane. Its available and in stock from shell lap supplies.

Cheers
 
AtomRat said:
Found the post here: https://www.prospectingaustralia.com/forum/viewtopic.php?id=8414

I see many hairline inner cracks ( bottom left ) but some seem to go in other directions along different planes or is that just me. Also are the lines to the bottom right cleavage as well or ..?
Click to expand...

I haven,t had a great look for the cleavage on that one yet. And I,m no Topaz guru. But on that one, IIRC, near the flaw there are parallel internal cracks. That I took to be the cleavage plane. I shall have another look.
But Refractol is good stuff. A bit stinky though.
There is also some info about the cleavage plane on gemology online also. I think many find it a bit trickyer on water worn topaz.

Cheers.
 
Mr Magoo said:
I shall have another look.
But Refractol is good stuff. A bit stinky though.
There is also some info about the cleavage plane on gemology online also. I think many find it a bit trickyer on water worn topaz.

Cheers.
Click to expand...

Well. I've had another look. And those 'cracks' are more of the inclusion/flaw. So I'm still looking.

But here's another link. http://www.gemologyonline.com/Forum...t=12174&p=123381&hilit=Topaz+cleavage#p123381
Say's pretty much the same. But shows how much it can be hard to spot especially on water worn pebbles.
 
Very visible here I can see the basal cleavage across the horizontal and verticle plane at the "base" of the crystal and through its verticle:
ORD89a.jpg


I think its very visible here on the front faces of the crystal, but also to the left and right edge verticle plane lines can be seen. I can also see on the chip half way up the right hand side a step like feature and possible cleavage showing there in the opposite direction of plane:
topaz-crystal-.jpg


I think the plane direction is obvious here pointing to the north west ( or is it going away from us )
236024_1314145776.jpg


To the bottom of this rock ( above the black mark, pit ) I can see steps and showing cleavage, also just above the large "step" to the top as well:
236022_1314145647.jpg


Can someone verify this for me by any chance please so I know im headed to the right direction. Im sure if we could pick them up visually it would be easier of course
 
Hard to tell without being able to physically pick them up and turn them over in the hand.

I think the cleavage in the second from the bottom photo is running from North East to South West.
 

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