Big lumps of?

[Una]

Hello Everyone,
Driving out bush a few days ago, I found these on the road and would love to know more about them if anyone hear can help ..
They could just be great lumps of dry clay.. but i thought they were still just too awesome to leave behind
These are the guys that i want to try and cut into slabs first.. Hubby did try (last photo) but they are rather chunky :lol:
The photos are of a few of the broken ones..
They are all also typically this round flat cow pat shape hahaaaa

 

[Lefty]

I'm no geologist but I'd say that's a rock

Hey, just polish that sawn face and see what it looks like. Interesting shape to them.

I'm not sure what's around Weipa, someone with more geology knowledge might know if there is anything interesting associated with bauxite deposits.

 

[Lefty]

Not sure what you are using to buff the surface but my grandfather used to polish truckloads of rock in a vibra-lap with tin oxide.

Tin oxide is a lapidary polish and it has worked on most things of I have tried it on , unless they are soft, then it tends to undercut them. I guess you could try it on a buffing wheel on a bench grinder, or even an angle grinder. Just make a paste of water and the white oxide poweder, it's a bit messy but generally effective.

You might have to order it in, Aussie Sapphire is one of many suppliers that stock it.

 

[AtomRat]

I did some knowledge smashing about geology last night l, ill give it a go. They have certainly been surrounded by an intrusive flow at some point. To me they are the same as the country rock around you / clay, shale or slate but you can see how they have a crust on the outside like a burnt muffin.

They may look slightly different as they were attempting to turn metamorphic but didn't have the temps or pressure to do so.

So basically, cooked clay or sedimentary rock.

 

[Mungoman]

I reckon that what you've got there are Nardoo stones, used to grind seed into flour.

 

[Una]

Hello Everyone, Thank you all for your input, I really appreciate it
The shape of them is quite amazing really.. They seemed to have been dug up in road works, they were everywhere..
I am probably the only person that has driven along that road and got excited over them hahahaaaaa

 

[Mungoman]

One other thing comes to mind Una. In my days, I used to be in road construction, using a boning rod, stakes on the sides of the road, and and strings to get the appropriate levels and camber on the road base, before sealing the lot with tar and fines.

We would go along and check after the grader had been through, and if there was an adjustment to be made, we'd place rocks next to the stakes to indicate where the grader needed to shave some more off of the road base. if there was a need to shave off 3 inches, we'd pile three rocks on top of each other, two rocks for two inches &c.

I'm wondering if what you've found are these indicators to the grader operator?

 

[Una]

The stones were everywhere, in no particular piles that I could tell.. they had been graded up and pushed to the sides of the road, the road was also covered in them (buried and exposed) they were just everywhere and all this same shape.. the ones we got were from off the middle of the road, there are hundreds still out there.. I am just really drawn to them, whatever they may be
I sliced one of the smaller ones up yesterday, the inside is gorgeous.. well.. at least I think it is hahaaaa
I posted a photo on my post in the lapidary thread (its the spotty one)

 

[blisters]

Una,

I'll take a stab in the dark and say pillow lava.

From what I can see in the photo the squarish rock held up looks volcanic, are there any crystals in there like plagioclase?

In the last picture the sawn piece I assume has the same content as the squarish piece. It has a crust but internally doesn't look like there are any further layers. The crust has large rocky objects in it which could be cause by lava hitting water but what I would expect is that any internal crystalisation will be larger than the external crust due to a longer cooling period. Is there much different in sizing of any crystals of the same type?

I can see what looks like vesicles top and bottom. If this is the case then this would be caused by escaping gases moving towards the top. The crust is thicker on top indicating a longer cooling period, i.e. more contact with water.

The shape is well, like a pillow but they are quite small. Here are some links to pillow lava showing shape and vesicles.

https://commons.wikimedia.org/wiki/File:Pillow_Lava_in_Bonin_Islands.jpg
http://2.bp.blogspot.com/-4W6X3ECSXGI/U4ZRo8_Wk0I/AAAAAAAAAtg/TlPRinpUCSA/s1600/budding+pb.jpg

Or maybe its a bunch of pebbles with a weathering profile... :8

Jon

 

[Una]

Interesting...
I have tried to take a close shot of the crystals, and also of a small one that I sliced up yesterday..
The crystals are larger towards the center, but not by a significant amount..
They are quite messy to cut and leave a wet clay mess.. They are all different on the inside..

 

[AtomRat]

Do they taste ok?

 

[Una]

They taste like clay!!
Hahahahaaaaaaaaa

 

[blisters]

Una,
Those last photos make a difference, forget about what I said earlier. These look like a mudstone/siltstone concretion. The veins come later and the source can be identified by the minerals. I can't id anything from the photos, I think I can see cleavage but only in one direction. The spotty pattern sort of looks like a laterite patterning but with no porosity. Initially I was wondering whether they might have been coloured by goethite above the pallid zone in the Weipa regolith but I don't know whether concretions occur there. See if you can latch on to a geologist up there I'd bet they could nail it in one.
Jon