Rock Identification

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I have a few rocks I would like some help with identifying
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90x Magnification
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200x Magnification
 
Another one.
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What could have made these indentations in this rock? Iron pyrite? Any other possibilities? 90x zoom.
 
You often have casts left where pyrite crystals have decomposed and been filled with quartz, calcite or other minerals. That might be what they are.
 
Can you post a few pics of the whole rock/s? And location where they were found? This will cut down some of the guess work.
 
that first pic of the whole rock has a great looking indicator line going down it, so more investigation is needed where it came from. should be good gold there if you can follow that line
regards trashy
 
Could be indentations from Limonite, I've seen thos before and it looks like that- but I'm no geologist. Top rock is mineralised quartz. I'd crush that and pan it off.
 
Thanks mfdes that was my thought on that rock.
There is gold there Trashy, gold that looks like it has rock stuck to it like in the first photo's. I know exactly where that rock with the black line came from.
HeadsUp I would have no idea about almandine garnet.
Thanks Everyone! I love this site!

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Ben I googled pictures of limonite and I saw the cube like pictures that came up. You could be right.
 
G day Hare-Twigga

Sample 1, Txet Book Granite I would say, the round glass grains are in fact quartz, the yellow would be pyrite, as when it fresh spilt it is yellow in colour, the cubic scares I would take a guess and say were left by Platinum, if you know the spot might be worth expanding your knowledge base on platinum, worth in the ball park of Au, Platinum in its life cycle is known to whether from igneous rock, it gathers into grains and then forms nuggets and placer deposits. So another area you may wish to invest some time in.

Sample 2, fine sample, text book dolerite, The small rectangles etc are from Plagioclase crystals.

Sample 3, the conclusions on limonite I'n not convinced, maybe the orangey brown part, but I ve never heard of limonite in red, or Fe2 influenced. Again any real conclusion would require some basic field testing, but what I think you have here is just a chunk of sedimentary stone, comprising mainly sandstone with some minor layers, of I don't know what, hard to tell from the photo.

Of course I could be wrong, I guessing from photos, so no shooting if I am.
 
Hey Village, the Limonite I was introduced to occurs in the rich red clay/siltstone adjacent to veins of iron rich quartz - I have seen the little cube shaped indentations like that in quartz there too. If I get a chance to this weekend I'll try to get a photo of the Limonite cubes insitu. But, again as I said up above I'm not geo, and you said you could be wrong looking at photos so I've probably got little to no chance :lol:
 
Thanks Village! I thought it may be a granite but it's so fine grained that I wasn't sure if it was still called granite. I know where the rock came from but in the river there doesn't seem to be platinum,very rough gold and specimens to a point not far above a dyke of some description. Maybe the granite cooked to a mica schist if thats possible. I've loamed the area with no color though.
 
That would be interesting Ben,rocks are so interesting! I should know more about them since my desk is covered in them.
 
hey guys

like I said I could be wrong, most definitely. From a photo your working by colour and at best what the texture might be, little lone doing any sort of confirmation testing, even basic hardness and streak testing. It may well be mica schist and limonite, limonite is a mineral based hydrated iron hydroxides and will some colour variation is possible, but under a streak test, it will illustrate its primary colour being brownish yellow or orange brown. It is in fact an oxide.

On the Platinum issue, it is the only mineral that would fit photo, being cubic and known to erode commonly out of the host rock. Again I could be wrong.
 
Village, I think the chances of me being wrong are some what higher then the chances of you being wrong. You can have an educated guess at what a rock is where as I just guess :D If you ever want to take a look at these area's I'd love to get your opinion on them. Go you halves in the Platinum Deposit! :D
 
I was digging a flat area to put a trampoline for the kids before Christmas and found this rock. Any Ideas?

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Hare_Twigga said:
Village, I think the chances of me being wrong are some what higher then the chances of you being wrong. You can have an educated guess at what a rock is where as I just guess :D If you ever want to take a look at these area's I'd love to get your opinion on them. Go you halves in the Platinum Deposit! :D

Platinum is $200 a ounce better then gold usually. For sure as soon as my calendar frees up, it's a bit on a short leash at the moment.
 

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