ID Metal thread formation in rock

[Powerhammer]

Hi all

I've cracked open this rock, put it under the microscope and found lots of metal threads some look like copper but others are a white yellow made up of very thin strands like rope. Im going to have it fire assayed but would like to know more about the thread formation and if Copper,gold, silver is deposited this way. The rock looks like an ironstone and is heavily mineralized. On the outside the rock it has a black splattering of dots which I believe is from the heat from its formation, when I use a probe and squashed the black splatter they are soft and smear silver without fracturing. Has anybody seen this formation before and if so what minerials were present.

Thanks

Powerhammer

 

[jethro]

Interesting. Are you sure the fibres are not organic left by a small spider or some sort of mould. The black specks that smear to silver may be Mica. as thats what it looks like in the mircoscope 'shot.

 

[Powerhammer]

Thanks Jethro
The microscope shot is highly magnified and shows 2 Sqmm, The thread formation is through the whole rock as I have broken it across multiple cleavages.
I have also found this formation in some samples I had assayed in WA which had high copper values. This rock is from SE Queensland.
the black splatter which I call spherical's behave like a metal and smear silver yellow. I'm hoping the spread ability is due to the gold content. It doesn't flake like mica but holds together like a metal. Fingers crossed the assay comes back with some gold values. Sorry about the clarity of the microscope image shooting down the eyepiece with an IPhone is a bit of a challenge

 

[Matt80]

The first thing that sprung to mind seeing the threads was asbestos, but l doubt it as they should be parallel to the best of my knowledge.

Honestly the rock looks sedimentary to me, like a mudstone or similar and if so then the fibrous inclusions wouldn't be a surprise. Hopefully lm wrong and it's an ilmenite or similar with good gold. I'm happy your getting it assayed as it's far more useful for all of us if we get answers to questions about rocks like this.

 

[Powerhammer]

Thanks Matt80
I'll post the assay results when I get them, the sample comes from a fault system and at the head is a limonite reef (Someone can please confirm) (attached photo) about 1/2 km away from where I found the original sample. There is also a large limonite geode (see attached photo). 20m from the original sample was this heavily mineralzed quartz type rock that has a lot of dark mineralization with some dendrite formation, it also has the same metal threads in some spots. I did find a cuprite floater on the other side of the hill some time ago so I'm thinking copper threads in the rocks and hopefully carring some gold. Has anybody seen a ore like this?

 

[Matt80]

It's a very interesting spot and certainly worth checking out. I'm sure lm not the only one here that would happily spend ages just looking at all the rocks whether there is any gold or not.

I wouldn't pretend to know anything like as much about these things as some of the other members here, but the first thing l would be doing is getting some of the heavily mineralised dirt that has decayed from below this deposit and pan it out. Finding gold in the pan would confirm your hopes, but of course not finding gold wouldn't necessarily mean their isn't gold there, just that it might not be free mill gold so might need processing. The second thing l would do is run a metal detector around the area, though l would probably be stopping too often to look at every bloody rock that looked interesting.

 

[jethro]

Great pics PH. That geode is an interesting formation. Looking at the original pictures agian it looks to be some type of metamophic rock. Please let us know what the assay says.

 

[Powerhammer]

I dollied up around the limonite reef and panned it but got no visible gold and there was nothing really to see under the microscope so I have been working my way down the creek line which is the fault. That's when I found the sample with the metal threads and the other white rock which is fine grained, no cleavage plane and heavy and very brittle,. Not sure if it is quartz though or contact metamorphic coming off the fault. Under the microscope it is slightly transparent with the dark mineral being heat affected and fused together and forming small dendrites. Has anybody seen anything like this?

 

[20x]

While pipelaying in a clayflat near Ipswich I was finding curved Shell like ironstonish pieces just like that about 2m down..

 

[Powerhammer]

Thanks 20xWater, If you get back up there you better see if there is any left on the surface and dolly it up .
I believe there was a large gold mine just south of Brisbane that was gold in Limonite in the old days.
I just visited friends in Brisbane and we walked the trails around the TV stations at Mt Gravatt, I never realised there are old gold mine workings there.

 

[Matt80]

I don't know what the host material was, but it was and still is common to find gold when council starts digging. The story bridge on the north side l believe had gold coming up when they were digging the foundations, but there are meant to be a bunch of places around the area it was found.