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 Post subject: Re: Garnets
PostPosted: Tue Mar 08, 2016 11:42 pm 
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Hooray, we got the go-ahead!!! Just been on the phone to the property owner and asked if it was ok to bring my trommel - she said we can do whatever we like as long as the cattle are not disturbed and fences and gates are left in the condition we find them in. I can't wait to rip into that schist bank with the jackhammer :D

And we hadn't even sent the peace offering yet. I just phoned my mate, he has just finished it, set in a combined gold and silver setting. I'll post it off to her tomorrow. It won't be going to their actual mailbox obviously, which is just an old cream can on a post on the side of a country road, it'll go to the mailing centre in Rockhampton, about 50 miles from the property. I guess they probably go to town about once a week for supplies.

Anyway, weather permitting we'll be heading up there on Saturday :D :D


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 Post subject: Re: Garnets
PostPosted: Wed Mar 09, 2016 11:21 am 
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Good news for you finally, Lefty! Please take pictures of the dig and of the green garnets you are going to find [-o<

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 Post subject: Re: Garnets
PostPosted: Wed Mar 09, 2016 4:17 pm 
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Will do ephsea :)

The vast majority of them will not be good of course - most gem mining operations have drums and drums of stones that didn't make the grade. The biggest problem with the ones from this site is excessive colour saturation. I closely examined some of the 10-20 carat ones we found last time with strong lighting and bemoaned the fact that if it wasn't for that they would have been beautiful stones - some are completely flawless.

But lighter bright reds are certainly there as well as pinks and occasional greens. I found an amber-coloured one there with green tints but it was too small to facet.

Not sure about taking the trommel this weekend because we need to work out where we can get vehicle access to the site itself to get something that size to where we need it. But I'm definitely taking the generator and jackhammer, I'll pulverize chunks of schist out of that gully bank and run it through a big sieve about three feet long. There will be four of us so between mechanical and hand power we'll put through some dirt.

And that's usually what it boils down to - how much dirt you can move. The stones are there but there can be a lot of dirt in between them, as is the case with the sapphires. With these things, there are a lot more of them in the ground than sapphires but you still have to shift the volumes of dirt to find the good ones.

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 Post subject: Re: Garnets
PostPosted: Wed Mar 09, 2016 11:24 pm 
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I would suggest you bring and hand deliver your peace offering, if for no other reason, a personal thank you. Really awesome you got the go ahead to dig!

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 Post subject: Re: Garnets
PostPosted: Thu Mar 10, 2016 1:52 am 
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Dan&Sally wrote:
I would suggest you bring and hand deliver your peace offering, if for no other reason, a personal thank you. Really awesome you got the go ahead to dig!


I would but I have no idea where the house is :) All I can see for miles is hills and cow paddocks.


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 Post subject: Re: Garnets
PostPosted: Thu Mar 10, 2016 10:06 pm 
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Sounds like home. Word of caution if they feed bales from a truck don't be surprised to wake up surrounded by cows rubbing against the truck looking for a bite to eat. They dent up your truck, won't get out of the way and become a general nuisance . cows are the dumbest thing on 4 feet. Better to park outside the fence. :?

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 Post subject: Re: Garnets
PostPosted: Thu Mar 10, 2016 10:43 pm 
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Yeah, they ain't the sharpest tools in the shed are they? :D I haven't ever actually seen any cattle at the dig site itself, I don't know how many head they're currently running on the place. We won't be camping this time but in a couple of weeks I'd like to spend three or four days there. There is a nice camp spot on a river crossing in the area but it's aboult half an hours drive from the site so we'd probably just camp there, and hope to not be accosted by cows :D


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 Post subject: Re: Garnets
PostPosted: Fri Mar 11, 2016 12:55 am 
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Odd question maybe? Why do you run a trammel and not use just a grizzly screen? Or are you washing as you run it through the trammel? Most trammels in use here are used as a wash plant to break up the clay prior to a concentrator of some type.

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 Post subject: Re: Garnets
PostPosted: Sat Mar 12, 2016 6:29 am 
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Dan&Sally wrote:
Odd question maybe? Why do you run a trammel and not use just a grizzly screen? Or are you washing as you run it through the trammel? Most trammels in use here are used as a wash plant to break up the clay prior to a concentrator of some type.


Yep - this ground is pretty damn hard and since my trommel - given that this is a mining thread, can we switch off autocorrect for this sub-forum, a trommel is a piece of mining equipment, not a spelling mistake :D - is a converted cement mixer, it can just keep tumbling a quantity of material until all hard clay is pulverised. Also, you can tip a bit of water in it and pre-clean the gravel.

Report on the days activities later, too tired right now.

Y'know, I think I've suddenly realized that I'm not 21 anymore :) Hard manual labour seems to be having a bigger impact.


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 Post subject: Re: Garnets
PostPosted: Sat Mar 12, 2016 1:12 pm 
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Ok, reporting in....

The night before last my father said to me "we won't bother taking the 4KvA generator, the little 1KvA will do, it's nice and light".

I said "you reckon that little thing will drive that demolition hammer - that's a pretty serious jackhammer, not a toy".

He says "yeah, I've tested it".

I said "did you test it under load?". He said he had so I just went with that. When we got there yesterday, we dragged that heavy jackhammer down the hill, started the little generator, plugged it in and attacked the bank - the hammer instantly died. Nope, there was no way that little thing could drive that demolition hammer, it just sucks way too much juice. You can hammer the empty air like a .50 cal with it plugged into that but as soon as you get serious about busting up hard ground, it just gives up the ghost. Seems dad's idea of testing under load was to stand it upright and pull the trigger, watched the pick drive into the ground and decide that was fine. Like driving a 4WD on an asphalt highway and declaring that to be a test of it's off-road capabilities - they aren't the same thing.

He has now been fired from position of equipment tester and relegated to making sandwiches and tea :)

So, a bank of extremely hard wash and only a few hand tools - any notion of moving a decent amount of dirt this weekend went straight out the window :( The two youngest blokes (myself and dad's next-door-neighbour) attacked the iron-hard gully bank with picks, chipping off what we could and smashing it up as much as possible.

Image

Got back a few dark stones from it but it was very hard, very slow going. The others began running out of enthusiasm and went and sat under a little shady tree and ate lunch. I had a bit to eat and sat down for about 15 minutes then dejectedly decided to just speck along the gully and bare ground patches.

Walked up onto a little rise opposite the bank, the ground was covered in little chips of the black stuff and a few red chips and bits of host rock containing garnet and black stuff...

Image

After scanning the ground I picked up a few of the expected....

Image
Image



Then something caught my eye. It looked like a piece of the black stuff but seemed transparent. I picked it up - it wasn't black at all and was
transparent. It's about 5 carats and better-looking than the photo shows. Hmmmm....

Image

There appears to be some sergeant-striping - doesn't look like a garnet to me. Looks rather familiar actually. But here, hundreds of kilometres this side of the field? Why not I guess, the area is heavily vulcanised. Perhaps old reports of green garnets in the areas have been mis-identified?

Hope to be going back there in a few weeks with all the equipment, I'm keen to see what might turn up when we actually move some decent amount of dirt, with me in charge of equipment testing :)

You never know what's around. 8)


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 Post subject: Re: Garnets
PostPosted: Sat Mar 12, 2016 2:13 pm 
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The green stone is very intriguing--I'd love to see a few more pictures if you don't mind taking them. The matrix is also quite odd. It is not a schist. Maybe a phyllite? It doesn't really even look metamorphic from the picture. What are the surfaces of the garnets like?

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 Post subject: Re: Garnets
PostPosted: Sat Mar 12, 2016 2:53 pm 
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I'll try to get some better pics of it Stephen - there even appears to be some blue in there at certain angles. That in combination with the yellow-green colour zones and what looks like the corner of a set of hexagonal stripes just made me think sapphire straight away. There are very old reports of sapphires having been found by gold prospectors in the general area a century or more ago but I have never come across anyone who claimed to have found one themselves.

There appears to be more than one kind of host rock. There is a flakey material that I took to be schist that I have found garnets and black stuff (for want of a proper name) in. In some cases, the garnets were flattened and fitted perfectly into the gaps between the flakes, giving the impression that they had formed in it.

But last trip, I found the rocks that you see in the image just a little further down the slope. There are quite a lot of them on one shoulder of the outcrop, ranging from golf ball size to basketball size. They look nothing like the flakey stuff and are superficially similar to some of the rocks further out on the sapphire field.

Do they look volcanic to you? Is garnet always found in metamorphic rock or can it actually form in cooling magma? Each piece of garnet and black stuff in these rocks looks to be encased in it's own little capsule and there are plenty there with empty pockets in the surface where the stones have fallen out.

I brought home another piece of the same rock that appears to have some kind of silvery-gold mica in it as well, will get a photo of that when the sun comes up.


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 Post subject: Re: Garnets
PostPosted: Sat Mar 12, 2016 2:55 pm 
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Quote:
What are the surfaces of the garnets like?




Mostly like a piece of glass broken from a larger piece, though some have a slightly "melted" appearance.


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 Post subject: Re: Garnets
PostPosted: Sat Mar 12, 2016 3:17 pm 
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Ok, this is about the same colour in sunlight as well.

Image

Two things I had difficulty photographing - one was the striping which although not that conspicuous definitely comes to a corner that if repeated around on the same angle looks like it would end up forming a hexagon.

The second is the colour shift. There is a definite shift toward a shade of blue as the stone is rotated away from this axis. The opposing axis is almost closed and appears to be very dark blue.

It looks facetable and I would do it for the novelty value except I think the closed axis would give problems and I think this stone would likely end up very, very dark if faceted. A pity because it's nice and bright through one direction, if it wasn't I would never have spotted it lying there among the other black stuff.


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 Post subject: Re: Garnets
PostPosted: Sat Mar 12, 2016 4:50 pm 
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The flaky stuff you describe does sound like schist. This stuff, though, definitely odd. Garnet can occur in a variety of contexts, including igneous rocks. The 'pocket' effect you're seeing is weathering of the outside of the garnets to chlorite. I'm really not sure what the rock is just from the photo--it could well be some odd igneous intrusion, though it being right next to the schist is a bit curious.
Is there any chance you could take a photo of the green stone in reflected light? It would also be good if you could carefully examine it for any cleavage planes. It does look a bit like a dark pyroxene or epidote, so it would be good to examine either of those possibilities as well.

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