Rock n Opal
- Thread starter jay
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Syndyne
Shaun Galman
Hi Jay,
What sort of rock matrix are you dealing with?
Is it ironstone boulder, Andemooka matrix or the sandstone-opal clay variety? Post a photo up if you can (might need to break the ten post limit before you can though) as that might help understand what you're dealing with.
Cheers,
Shauno.
What sort of rock matrix are you dealing with?
Is it ironstone boulder, Andemooka matrix or the sandstone-opal clay variety? Post a photo up if you can (might need to break the ten post limit before you can though) as that might help understand what you're dealing with.
Cheers,
Shauno.
Syndyne
Shaun Galman
Ahh, okay. No worries at all there.
The way we usually go about sawing opal (if it can't be simply shaped or cabbed on an ordinary 8 or 6 inch diamond wheel on a lapidary cutting machine) is using a thin 150mm diametre x 0.25mm thick Diamond blade with a water feed on a jewelers table saw. I wouldn't recommend hitting it with anything to break the opal out as the shock will usually destroy or shatter most of the opal content.
A photo will definitely help me see what you're looking at. My father has always been one of the best opal cutters here in Lightning Ridge and I'm not too bad at it myself so you're in good hands. If we can't help you out then there's something wrong
Kindest regards,
Shauno.
The way we usually go about sawing opal (if it can't be simply shaped or cabbed on an ordinary 8 or 6 inch diamond wheel on a lapidary cutting machine) is using a thin 150mm diametre x 0.25mm thick Diamond blade with a water feed on a jewelers table saw. I wouldn't recommend hitting it with anything to break the opal out as the shock will usually destroy or shatter most of the opal content.
A photo will definitely help me see what you're looking at. My father has always been one of the best opal cutters here in Lightning Ridge and I'm not too bad at it myself so you're in good hands. If we can't help you out then there's something wrong
Kindest regards,
Shauno.
Syndyne
Shaun Galman
Hi Jay,
Looks like a Yowah Nut from Yowah, QLD. I may be wrong however as boulder can take on that appearance also, though usually a darker brownish colour.
Being a predominantly blue colour bar (lowest quality and usually least valuable) I wouldn't be too afraid of giving it a gentle hit to expose more colour. You do run the risk of it being the only bit of colour showing so don't be upset if that's as good as you'll see on the edge there. If you can't see the same colour seam on the other side and running through the piece then this scenario would be ideal if you can't get it to a cutter to gently rub it down to the colour bar.
In my opinion, it's probably best left as a whole specimen.
Due to the thin nature of the opal seam in that piece I would probably try and break it near the opal seam (not directly on it) by hitting it gently just above it near the thinnest edge above the colour seam (top right part of the first photo you posted). Remember that you may destroy the piece entirely if you go this way.
Let me know how you go if you decide to be brave.
All the best with it mate.
Shauno.
Looks like a Yowah Nut from Yowah, QLD. I may be wrong however as boulder can take on that appearance also, though usually a darker brownish colour.
Being a predominantly blue colour bar (lowest quality and usually least valuable) I wouldn't be too afraid of giving it a gentle hit to expose more colour. You do run the risk of it being the only bit of colour showing so don't be upset if that's as good as you'll see on the edge there. If you can't see the same colour seam on the other side and running through the piece then this scenario would be ideal if you can't get it to a cutter to gently rub it down to the colour bar.
In my opinion, it's probably best left as a whole specimen.
Due to the thin nature of the opal seam in that piece I would probably try and break it near the opal seam (not directly on it) by hitting it gently just above it near the thinnest edge above the colour seam (top right part of the first photo you posted). Remember that you may destroy the piece entirely if you go this way.
Let me know how you go if you decide to be brave.
All the best with it mate.
Shauno.
Thanks for the advice Shauno, I think you maybe right about where the boulder came from. Up close you can see different colour seams but I think I'll leave it as a complete piece. People love looking at the different colours it shows, even though they are thin seams. I do have another piece which I will chip away at. I will post pics showing the results.
Once again thanks Shauno...
Once again thanks Shauno...
Here's a boulder from QLD, I think my parents came back with it
from a trip in the 80's. Just for reference.
from a trip in the 80's. Just for reference.
Syndyne
Shaun Galman
jay said:
Hi Jay,
Yep, it sure does. The quality of the colour and pattern are major players with the prices of opal. Once you have an exceptional quality play of colour with a good pattern then it's the carat weight and cut that determines the price. After that it's only the matter of settling on a decent price with an opal buyer to deal with
The colour scale goes: blue, blue-green, green, green-gold, green-orange then onto the rarer reds which usually have a mix of all colours in the better quality stones.
With the gem quality black opal we get now and again here at Lightning Ridge, the best quality colour usually sits on a dark to jet black potch. This kicks the colour and gives it the real black opal look. Some of the most expensive stones have a deep metallic red colour known as Pigeons Blood Red. I was fortunate to find a few small gems of this superior quality colour myself back in 1999. Those little stones in the small 1 to 4 carat range averaged $7000 per carat. I had never dug stones as good as those before and haven't since. In a total of 26 (50x50metre) claims that I worked by hand over 16 years, only three produced good payable opal, the rest only had lesser traces of opal or nothing at all.
There's always the exception to the colour scale rule and that comes in to play with the quality and size of the piece. For example, I've been fortunate enough to hold a single nobby (the nodule form of opal) owned by a long time miner and good friend of ours that was green-gold in colour with a small harlequin pattern (small even 3 to 4mm squares of colour and very rare) that weighed 472 carats. The colour bar was around 15mm thick sitting on black potch around 8mm thick. It was slightly larger than an old tobacco tin and just fit in the palm of my hand. It was valued at $2800 per carat which made it worth $1,321,600.00 Needless to say I was slightly shocked to be able to see, let alone be privileged enough to hold something like that. I know of many more pieces that far exceed that single nobby in size and price.
We also have dug a few gem quality blue and blue-green stones over the years as these are the more common colour types. Some of those, particularly from a field known as Jag Hill were very valuable due to the good quality nature of the colour (a very metallic sheen) and patterns along with their larger sizes after they were cut. The better stones were usually in the $1000 to $2000 per carat range. Those were between 1 to 40 carats in size.
Opal has many characteristics that need many years of experience to know well and understand fully. I think this is why many are afraid to purchase a good stone, both free and in jewelery. Couple that with the fact that Australia's national gemstone usually doesn't stay in Australia for too long and it's clear why opal doesn't do well here in Aus. Seems to be a common trait with most trades today
Cheers,
Shauno.
Cheers, hope you don't mind I have copied this to file. You've definitely kicked off some real curiosity.As suggested I have kept the piece as a whole speciman. Look I have another rock unsure exactly what it is but has colour. I'll load up some snaps and post them.
Cheers Shauno,
Jay
Cheers Shauno,
Jay
Syndyne
Shaun Galman
Ben78 said:
G'day Ben,
Cheers! It can be extremely valuable when you have a claim producing gem quality opal. The best price paid for a single little 1carat gem was $30,000.00 back around the year 2000 when prices were at the end of the peak before dropping off. That little stone came from a field called The Rocks which is situated out in the central area of the main Coocoran Opal Fields. I believe it was cut from a small fossil of opalised wood of all things. Once a claim has good opal, it usually gets into everything in the known carrying band in the level.
I still have to do some writing for the Opal Mining At Lightning Ridge post I put up in this section of the forums. I'm trying to get a decent assessment of the current situation as far as opal pricing is going. We stopped mining in 2010 as it went badly downhill from about 2005 onwards due to the effect of the GFC. I'm not hearing many good things from those that are still mining today.
Regards,
Shauno.
Ben78
Ben
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Is there 'missed' opal to be found on the mullock or is the only way to find it to dig for it yourself? Seen pics of the White Cliffs fields, looks like a lot of dirt gets discarded. I remember my parents getting 'opal' but nothing like what you see on the 'this is what opal looks like' websites. Probably came from Coober Pedy but could just as easily have been Andamooka or somewhere else in SA
headbut
Paul
Wow Ben78 , is that in possesion or from the net , that is a beautiful stone
