Melted glass

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Hi there. My friend found this while out rock picking. She can't remember exactly where she found it. It would be in the Central Qld area. We are both new to rock picking16740161324081989463243685126755-removebg-preview (1).png ei_16740163715017112982811994025306-removebg-preview.png
 

Simmo

Always fixin' sumfink......!
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Welcome to PA!
I'm sure someone on here could have some insight as to what it is?!
 
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If you can scratch it with a needle it is probably a carbonate mineral - more probably you cannot and it is silica (eg chert).
 

Hawkear

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Have often found dollops of melted glass in the Victorian goldfields. Caused by bushfire hotspots eg around intensely burnt tree roots which are common places where old broken bottles may have lain.
The folded bit at the front in Pic 2 seems to have a very even thickness which would be unusual in nature, so my bet would be melted glass.
 
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Have often found dollops of melted glass in the Victorian goldfields. Caused by bushfire hotspots eg around intensely burnt tree roots which are common places where old broken bottles may have lain.
The folded bit at the front in Pic 2 seems to have a very even thickness which would be unusual in nature, so my bet would be melted glass.
Maybe, unless it just looks folded. It has a fine granularity to me (as in chalcedonic silica) unlike the smooth uniformity of melted glass). It also has areas of distinct colour variation - glass bottles are usually uniform in colour and they stay uniform when they melt.

1674102531544.png
And as for uniform of layering in chert - in no rock is it more common (well, perhaps some ironstone).1674102820033.png
Who knows?
 

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Nothing is certain from remote images. Just picking up on clues.
Another one maybe the area of refraction (rainbow colours). A prismatic thickness of glass can do that. There appears to be an white opaque area (crack or inclusion) where that prismatic light separation is projected and can be seen in a single view In the photograph.
Correct me if I am wrong but I understand that natural silicates like opal will also display a range of colours, but I believe they will flash with one colour at a time rather than in a continuous spectrum that can be photographed from one viewpoint at any one time.
Maybe our opalites could comment on my presumption there.
 
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Nothing is certain from remote images. Just picking up on clues.
Another one maybe the area of refraction (rainbow colours). A prismatic thickness of glass can do that. There appears to be an white opaque area (crack or inclusion) where that prismatic light separation is projected and can be seen in a single view In the photograph.
Correct me if I am wrong but I understand that natural silicates like opal will also display a range of colours, but I believe they will flash with one colour at a time rather than in a continuous spectrum that can be photographed from one viewpoint at any one time.
Maybe our opalites could comment on my presumption there.
My guess would be that the granularity precludes opal - more likely chalcedony that does not display those colour characteristics. Opals are not coloured and the colours are caused by light passing through different diameter spheres with intergranular water, whereas chalcedony is just interlocking chalcedony grains (often as radial aggregates). The diffraction effect splits the passing light into different wavelengths (colours) as with a prism or rainbow. Grainsize tends to be very different, chalcedony being much larger.

1674125357576.png

1674125513585.png chalcedony

But we have nothing truly diagnostic.
 
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