Zircon and other clear stones identification

Following our recent experienced fossicking at night on a Minefest trip, we purchased a couple of 365nm torches for future night time jaunts. So far it's been an interesting journey into a new realm of gems and it has left us a bit perplexed.

Last night we had a cleaning session, bought a $40 bucket of rocks and stuff from Mr Tumbles and washed them last night, then for fun turned off the house lights and brought out the UV, WOW... we had some stuff light up so we took it further and explored a bunch of stuff from the Rubyvale area, it also lit up!

What we had learnt at Minefest is that Topaz lights a brilliant orange under 365nm and we had a bunch of it, much of which we had been previously told was clear Zircon??

Some digging around on the 'www' indicated that clear Zircon is rare, Topaz is common, how true this is I am not sure, though the sources seemed credible... GIA etc, but I couldn't find any info on Zircon and UV.

So now we are in a state of total confusion as to what we actually have, all we do know is we have a variety of clear stones, could be Zircon, Quartz, Diamond (very unlikely) and Topaz, we know Topaz glows under UV, so what are the others and how do we confirm??

As an aside, put the wife's engagement ring under the UV, 5 faint blue glows and one brilliant white, like a star in the night sky... unbelievable, all diamonds though according to the valuers!

I'll set up the camera and take some photos over the weekend.

Over to the Brains Trust...

http://www.geo.utexas.edu/courses/347k/redesign/Gem_Notes/Topaz/topaz_main.htm
Topaz U.V. Fluorescence: weak; blue and colorless topaz may show a weak yellow or greenish glow under long wavelength u.v.. Sherry-brown, pink, or golden yellow topaz may show a strong orange-yellow fluorescence under long wavelength u.v. light that is much weaker under short wavelength u.v. light.

I've never seen topaz flouresce. All the thousands of zircons I have found absolutely none of them flouresce under any uv lights I have. Most zircons I have are a reddish colour and champagne straw type colour, most are extremely clear.

Some pics would be very helpful, try to do some under normal white light and then under the UV.

Here's a diamond flourescing under UV, only about 10% do. You can see the ones next to it have no flourescence at all. The 1ct centre stone is a cognac diamond and it has a mild flourescence.



Rubies under UV. The top pic is no UV.





A topaz under UV which does not flouresce in my opinion, a mate cut this one for me.



I did all these pics myself too.

Anyway from what I've seen a strong flourescence is quite rare in most gemstones apart from ones that are known to give strong flourescence such as most rubies and occasional diamonds. I'm not saying others don't as a lot do but I think the region they come from can be important as well regarding flourescence

Love my Fluorescent Minerals.... My Uv torch comes out at every Gem Show... ]

LW....

Quite a few differences between topaz and colourless zircon, though it may not be readily observable from a small, water-worn pebble.

Topaz is harder than zircon and has perfect cleavage in one direction compared to zircon's imperfect cleavage in two directions. Topaz doesn't display visible double-refraction while zircon shows it strongly.

A topaz crystal that has not been rounded by weathering has a fairly distinct look about it, with a four-sided "diamond-shaped" cross section (the point can sometimes be more complex) and striations running down the length of it rather than across it like quartz.

With large enough zircons with clean faces that can be seen into, you can often see the double-refraction using loupes. There is a distinct "fuzzy" look when looking through it and a single surface feature on the outside (say a surface crack) appears double if you look very closely from the other side, two identical cracks running beside one another.

Lefty said:

Quite a few differences between topaz and colourless zircon, though it may not be readily observable from a small, water-worn pebble.

Topaz is harder than zircon and has perfect cleavage in one direction compared to zircon's imperfect cleavage in two directions. Topaz doesn't display visible double-refraction while zircon shows it strongly.

A topaz crystal that has not been rounded by weathering has a fairly distinct look about it, with a four-sided "diamond-shaped" cross section (the point can sometimes be more complex) and striations running down the length of it rather than across it like quartz.

With large enough zircons with clean faces that can be seen into, you can often see the double-refraction using loupes. There is a distinct "fuzzy" look when looking through it and a single surface feature on the outside (say a surface crack) appears double if you look very closely from the other side, two identical cracks running beside one another.

Click to expand...

Going to take some stones over to Chez tomorrow when we go for our second faceting lesson, he should be able to clarify the critical points of identification, I'm one of those people who needs to see to comprehend.

Thanks for your input mate.

Took some pictures this evening, first pair are pretty self explanatory, one is under daylight illumination and the second is the same grouping under 365nm UV. When we went on the evening fossicking trip we were told the yellow/orange stones were Topaz. What are the others??? The bottom left I feel is probably quartz but the blue ones???




The second pair are a stone we came upon which looks well water rumbled, but due to its size and shape we suspect is synthetic, but lights up like Topaz, so overall are very unsure, it's 205ct




Anyone got any ideas?

Have you tried a scratch test on it? At that size and shape I'd suspect glass which will be pretty easy to scratch. Maybe test some old glass bottles and stuff and see if they fluoresce orange as well (might depend on the ingredients I guess)

Scratch test: Glass; No, Quartz; No, Garnet (not confirmed); No, Sapphire;Yes

You mean you couldn't scratch it with anything other than a sapphire?

Yep

Interesting.

This came from a purchased bucket of wash?

Perhaps it's a piece of synthetic sapphire?

Hello Gents

We were in Glen Innes last year and bought 3 bags of wash, there is supposed to be a piece of amethyst in there as well as sapphires,

There is a local cutter that sends a lot of his mistakes into the bags of wash as well

Have not sieved the bags yet, they are in storage back in Sydney and we are in Adelaide ATM, so I guess anything is possible

ray

Lefty said:

Interesting.

This came from a purchased bucket of wash?

Perhaps it's a piece of synthetic sapphire?

Click to expand...

No it came out of a bucket of stones from Mr Tumbles at their clearing sale, real mixed bag of river washed pebbles, polished stones, cut material for cabbing and a small pot of mixed gems. Due to its shape and the fact that it lit up under UV, started thinking it might be Topaz as it's relatively common in the area following all the tin mining and the miners used to chuck them away or bag a bury them as both sapphire and topaz used to blocked their wash plant.

Did an SG test and bang on 2.6 so looks like we might have a lovely lump of Citrine, believe this might stack up on the scratch as well as the only gems we have which are harder that we can positively identify are sapphires. No answer for the UV response though.

Still happy though as Citrine cuts to a beautiful gem, albeit not of high value, but $$ ain't everything

Still no idea what the UV blue stones are?

Dihusky said:

Did an SG test and bang on 2.6 so looks like we might have a lovely lump of Citrine, believe this might stack up on the scratch as well as the only gems we have which are harder that we can positively identify are sapphires. No answer for the UV response though.

Still happy though as Citrine cuts to a beautiful gem, albeit not of high value, but $$ ain't everything

Still no idea what the UV blue stones are?

Click to expand...

It looks like it would return a good-sized gem, has a pretty well perfect shape for a long step cut or something similar.

I've never used UV on stones before so I can't be of much help there

Thanks Lefty, exploring all options but yes a long step cut could be on the cards when I learn how. Recon this could easily yield more than one gem with some judicious cutting, the piece is 16 x 20mm and 52mm long so I think there are a few options.

Found some more of the stones that light up blue under UV and did some tests to try and identify. They are clear without any definable colour cast, Moh above 7 (must get some test pencils!) and SG of 3.2 searched the internet for an identity and couldn't find anything to match these criteria. The closest was Kunsite, but this usually has some colour. Anyone got any ideas???