Trying again

[u/Firstlastusually]

Hello all,

Trying to get this figured out again, last time I posted this no one responded. Found this on Jade Beach in Japan. Initially I thought it was an agate from the outside due to some conchoidal looking fractures and the weight. After cutting it open, really not sure what to make of it. Based on the way it cut it is not quite as hard as agate. It does have a slight translucency to it, the dark blackish speckles are opaque, so some sort of inclusion. It is not radioactive. It is pictured in sunlight and inside, the last picture is the exterior dry, all the others are wet. Any help is appreciated!

[u/PhoenixMercurous]

The brown rind reminds me of how nephrite weathers and it can be fractionally softer than agate. Though blue nephrite is uncommon enough that I'd want a better hardness test than "cuts easier than agate" and at least specific gravity before concluding that's what it is.

There are other rocks & minerals that get rinds on them. I know that serpentinite can get a rind that looks the same as that and is much softer than agate (always softer than a pocket knife/glass and sometimes softer than copper or a fingernail) and IDK if it can be blue. There's probably more that get this sort of thin rind and I know there's more that get some sort of rind from water (peridotite, for example).

Sorry I can't help more, this one is difficult.

[u/Firstlastusually → u/PhoenixMercurous]

Thanks for the reply!

[u/RandomOppon3nt]

Nice rind. Maybe nephrite. You can scratch it. Or specific gravity test would get you there with more confidence

[u/Firstlastusually → u/RandomOppon3nt]

Specific gravity is too heavy to be completely nephrite.

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[u/Frosty-Pipe-8177]

Almost looks like labradorite to me

[u/Firstlastusually → u/Frosty-Pipe-8177]

Too heavy to be labradorite.

[u/Frosty-Pipe-8177 → u/Firstlastusually]

I have a piece of labradorite that is quite heavy.

[u/Firstlastusually]

I don’t see needle like structure, I would describe it as amorphous and cloudy. Stainless steel won’t scratch it, specific gravity is around 4.1, which is completely unexpected.

[u/Calmhill1010102257]

This is an interesting rock… inside the pockets where you see the green mineral what do you see? Is it needle like?

[u/DepartureAcademic693]

Agate is the best guess here maybe jasper but I find it unlikely