I'm used to seeing quartz veins in granite but these stones I've seen in Guérande, France, seem to have veins composed of granite with bigger-sized crystals. How could this happen ? Could it be from later infiltration of magma ? Could it be anatexy ?

I read that most of the granite is already anatectic. Could there have been several episodes ?

i found this in the surf at Myrtle Beach, South Carolina. its about hand-sized and unusually heavy for its size. it doesnt fizz with vinegar, and a fridge magnet seems to weakly attract it (or almost feels like the rock pushes the magnet). it has flat layers and white veins running through it.
any ideas what it could be? i included photos of both sides and the edge.

Finding "cool rocks" with my toddler at the beach today, and I almost passed this one up. I initially thought the white portions were barnacles, but when I picked it up, I noticed that they were opalescent and appeared to be "growing" from the pebble.

I'm by no means a rockhound, so my apologies in advance if this is a stock standard beach find.

Also, r/whatisthisrock is not allowing image posts at this time...? So no luck over there.

Found in a state park in upstate NY, Ithaca region. I'm not a geologist but I have an amateur level of interest. I noticed that it is both layered and sideways. Does that mean it got sandwiched first then turned? My assumption is that it was always like this and not moved by people I guess.

My mouth keeps wanting to say tourmaline crystal.

Found this In Kentucky, I was curious what mineral will glow green under UV in the Devonian black shales, I figured maybe uranium or maybe zinc? But I have no idea otherwise. FYI it is green in person it is just overpowered by the blue under the loope

The break was horizontal and not aligned with the bedding of the sandstone, which seemed weathered by shallow seas? Sydney sandstone in blue mountains.

Found in the middle of nowhere Wyoming. Could this be your standard regular sinkhole, or is there more going on here?

To my eye it looks very square and unnaturally-shaped. Is there any possibility that natural processes could create such a range?

Hello, I have some bones that I’d like to use for a necklace and I am looking for suggestions on stones (or even other materials, like wood or anything else) that occur naturally in Souther California that could be used as accents. I want everything to be natural materials and local to SoCal because I want this to represent my home. Thank you in advance

So I hope its ok if i ask in this sub, I'm currently making a work of fiction and I wanted to include a mine that was originally intended to extract one valuable metal that has largely been exhausted of this but is continuing at a smaller scale extracting something else of a lower value. In the context of the story it would need to be something that could be extracted and refined by pre-industrial techniques, and is still useful in that situation rather than something mainly extracted for electronics or the like.

I know silver is often extracted from ores with a lot of lead in them to, so my current idea is maybe it was originally a silver mine then after the original owners largely abandoned it maybe someone is still extracting and refining lead. But I don't know if you'd get a scenario reasonably where someone had gone in and extracted most of the ore that'd have a high silver content and leaving a bunch of lead ore that'd have very little silver left. Probably using something that predated the mercury method.

I found it on a beach of Vasto, Umbria, Italy

Please help me understand these formations better. This is the Cape Elizabeth area of coastal Maine. (Dog added for scale.)

Not quite sure what I'm looking at here but thought it looked interesting. Is this glacial striation? It was running west to east in the Raft River Range in Utah

Hi I know very little about geology but am trying to learn a bit more about what's around me! Found in Northern Great Plains region of the US, possibly septarian nodule based on a quick search? Huge pile of it and am curious so any nerdy info or insight is welcome and encouraged!

What are these circular patterns found in this rock at Whitby, Scarborough. They are very hard and sharp with one large circular pattern and a few smaller around it. Is it manmade of natural?