Cool rock I found in a parking lot

Any idea what kind it is?

71 points · 8 comments · view on lemmy.world

8 Comments

TheLeadenSea@sh.itjust.works · 3 pts · 199d (1 reply)

That is a very cool rock!

negativenull@piefed.world · 2 pts · 199d

I thought so!

Masterkraft0r@discuss.tchncs.de · 2 pts · 155d (2 replies)

I think it's some kind of (maybe hydrothermally altered) sandstone.

That vein is quartz, i'm pretty sure. Does the rest have a slightly grainy texture or is it smooth?

negativenull@piefed.world · 1 pts · 150d (1 reply)

It's fairly smooth. I agree the vein is quartz.

I think it might be petrified wood

Masterkraft0r@discuss.tchncs.de · 1 pts · 148d

I don't know. Petrified wood isn't all that common. Why do you think it's that?

To me it looks like a finegrained, silicious, sedimentary rock. Might be slightly hydrothermally altered or metamorphosed, can't really tell from the photos.

That's not to take away from the coolness of the rock though. It absolutely is a cool rock. I absolutely adore that quartz vein.

1984@lemmy.today · 2 pts · 200d (1 reply)

I asked chat gpt because I was curious...


The rock appears to be iron-stained sedimentary rock, most likely:

Sandstone or siltstone

Reasons:

Brown/yellow coloration typical of iron oxide (limonite/goethite) staining

Visible layering and flaking, suggesting sedimentary bedding

Fine-grained surface (no large visible crystals)

Breaks along planes rather than showing crystalline fracture

The reddish area

The darker red patch may be:

A small iron-rich concretion

Or possibly a fragment of jasper (iron-rich microcrystalline quartz) embedded in the host rock

Less likely options

Not granite (no visible interlocking crystals)

Not basalt (wrong color and texture)

Not metamorphic schist (no clear foliation or mica sheen)

If found in Scandinavia, this type of iron-stained sandstone/siltstone is common in sedimentary formations and glacial transport deposits.

For more certainty:

Check if it scratches glass (quartz-rich sandstone will)

Drop vinegar on it (if it fizzes, it contains calcite → limestone component)

Note where it was found (coastal, inland, quarry, etc.)

Most probable identification: Iron-rich sandstone or siltstone.

negativenull@piefed.world · 2 pts · 199d

That's interesting. I'll have to do some tests. Thank you!

beejboytyson@lemmy.world · 2 pts · 199d

Nah bruh that's cow shit. Why you put cow shit on the table? /j