d_day

Not a meteorite. It is a heavily weathered septarian nodule.

Sedimentary rocks can be quite porous, particularly those whose deposition is from evaporation, like travertine.

Looks like travertine to me.

Nothing about those two statements is contradictory.

It can happen to any stone, and can be cemented with virtually any mineral. Pressures on the stone cause it to crack. Mineral laden water seeps through, leaving behind whatever mineral it was carrying, which cements the pieces back together.

Photos are showing now, at least for me. None of those look like petrified wood to me.

Basalt often contains enough magnetite to attract a magnet, but I think you’re right that this is slag.

For starters, meteorites don’t have large bubbles in them, this is a typical feature of slag, and of vesicular basalt. Both can contain enough iron to attract a magnet, which often leads to confusion among beginners and novices since that’s a diagnostic of some types of meteorites. I’m no expert on meteorites, but I’ve seen enough meteor-wrongs of this type to say this is terrestrial in origin.

That was my first thought as well.

The layering seen here would rule out coprolite. I’d guess you’ve got some calcite there. It’s very difficult to ID minerals from photos alone, so I can’t be certain.

I think it’s most likely to be calcite.

I’m not convinced it is a fossil. While it does look strikingly similar to abalone, it also looks like it might be a fragment of an ironstone concretion.

I very seldom say this, but your latest photos have me convinced. I am 100% certain this is an agate.

Looks like a run of the mill agate to me. Several of the pictures show a seam between the two halves. The last photo shows some faint banding near the top.

The only mine in the US is partly owned by China. https://en.m.wikipedia.org/wiki/Mountain_Pass_mine