🔎 UNIDENTIFIED What is this rock?

[lialialemon]

Hi all you geology sleuths I found this on a beach in New Zealand. It is lighter than stone, it is rock hard, and does not have any residue that transfers to material when rubbed.
It does not make marks on anything except unfinished porcelain, it makes a dark brown line when drawn across it.
Wondering if it could be petrified wood, or maybe jet?

Thanks for your help!

 

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[ticndig]

coal

 

[traveller777]

I am no expert on the geology of New Zealand, so not sure Jet can be found there, but not sure why not. If that is Jet it is some big chunks. Jet is a form of Lignite, which is the lowest rank of coal. It does streak brown/ginger brown. Coal streaks black.
Based on the limited information, the streak, and the pictures I would say it is jet. I saw a lot of finished jet products at Whitby on the North Sea. They thought it was gold from the price they wanted. But lots of tourists there so prices always higher.
Nice find.

 

[traveller777]

By the way welcome to Tnet. I hope your time here is rewarding. Lots of great folks here to help you learn and to learn from you.

 

[Zakon Krzyżacki]

Coal. Anthracite specifically.

 

[traveller777]

Coal. Anthracite specifically.

Coal streaks black, correct?

 

[crashbandicoot]

Welcome to Tnet!

 

[traveller777]

Please keep posting your finds on here. Looking forward to seeing them.
Cheers.