Please Help rock ID

[catfishjim90]

Found this 48 pound stone gold prospecting in a bedrock creek 70 miles north west of St.Louis Missouri. It is roughly 12“ x 7“ . Weighs 48 pounds. Highly magnetic. Has a 1/4” outer crust.
Here are hopefully good pictures of the stone. One piece has been cut off.
thank you
Catfish

 

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[arizau]

Found this 48 pound stone gold prospecting in a bedrock creek 70 miles north west of St.Louis Missouri. It is roughly 12“ x 7“ . Weighs 48 pounds. Highly magnetic. Has a 1/4” outer crust.
Here are hopefully good pictures of the stone. One piece has been cut off.
thank you
CatfishView attachment 1798869View attachment 1798870View attachment 1798871View attachment 1798872View attachment 1798873

Is that thing really blue inside? I am color blind but that is the color I see.

 

[Goldwasher]

highly magnetic. means iron will stick to it. if it is attracted to a magnet it could be ferromagnetic. Some sort of mineral with a lot of iron.

Magnets will attract to certain minerals that aren't technically magnetic.

A minerals magnetic property is based on how it's magnetic field affects certain objects that would react to its type of magnetism.

 

[Goodyguy]

Sedimentary. Your sample appears to be illuminated with UV to me. My guess is calcium carbonate precipitated into mudrock or formed as a concretion, either way it would be attracted to a magnet as calcium carbonate (calcite) is diamagnetic in nature.

Also the fine crystalization is consistant with calcium carbonate concretion.
Plus the blue/purple color shown above under UV is consistant with that displayed by certain examples of calcium carbonate under UV.

Tough to make a definitive ID without a hands on inspection. Educated guess only.

Hope this helps,
GG~

 

[catfishjim90]

Thanks Goodyguy. For the info.
this is such a weird rock. It is strongly attracted to a magnet.
and very heavy for its size 48 pounds . I illuminated the picture with a regular flashlight no UV.
Where could I take it To get a definite ID. I would even pay. Thanks again Catfishjim

 

[arizau]

Thanks Goodyguy. For the info.
this is such a weird rock. It is strongly attracted to a magnet.
and very heavy for its size 48 pounds . I illuminated the picture with a regular flashlight no UV.
Where could I take it To get a definite ID. I would even pay. Thanks again Catfishjim

You say it is strongly attracted to a magnet. Do you mean as strongly as a magnet attaches itself to steel?

Look up nickel minerals or ores and see if any of those descriptions match what you have. Nickel itself is magnetic and heavy so it makes sense to me that the minerals would be too to some extent. You may live near a university that has a geology department with someone who would be willing to look at what you have or just the smaller hunk you sawed out and ID it for you.

I bet that slabs or cabochons of the rock would polish up nice. Retirement centers often have lapidary groups that may be willing to do some of the work including setting them in jewelry pieces.

Good luck.

 

[catfishjim90]

Thank you arizau.
I will check out your info.

 

[Goodyguy]

Thanks Goodyguy. For the info.
this is such a weird rock. It is strongly attracted to a magnet.
and very heavy for its size 48 pounds . I illuminated the picture with a regular flashlight no UV.
Where could I take it To get a definite ID. I would even pay. Thanks again Catfishjim

I'm stumped, the color and the magnetic properties dont seem to go together.
Arizau gave you great advice, If it were mine I would be taking it to a university for positive ID.

I have never seen anything like it.
Please let us know what you find out. Very interesting specimen.

GG~

 

[smokeythecat]

Could be an iron precipitate like hematite rounded into that form. The UV light is reflecting off of it, giving it a bluish tint.

 

[Goodyguy]

Could be an iron precipitate like hematite rounded into that form. The UV light is reflecting off of it, giving it a bluish tint.

The OP said NO UV light. Regular flashlight only!

That's what stumped me. I assumed it was under a UV light .

 

[catfishjim90]

Thanks guys for the info. I will try to take some more pictures and post them

 

[arizau]

Thanks guys for the info. I will try to take some more pictures and post them

Outside in natural light would be good.

 

[Goldwasher]

looks more like an intrusive rock than sedimentry

 

[Goodyguy]

looks more like an intrusive rock than sedimentry

The overall shape combined with a crystaline interior and a outer shell with voids between it and the inner mineral still has me leaning toward sedimentary, like a geode. Although intrusive is a viable possibility.

GG~

 

[catfishjim90]

I think I just found out what it is.
Basalt rock ingenious intrusive?

 

[Goodyguy]

I think I just found out what it is.
Basalt rock ingenious intrusive?

Was that conclusion arrived at after a hands on inspection by an expert?

Basalt is most commonly grey or Black but can be viewed as brown or rust colored after weathering if iron oxides are present which would explain the magnetic attraction.

Have you been able to identify the blue mineral?
Also curious as to whether the magnet is only attracted to the outer shell and not the inner mineralization or both?


GG~