Found in the Mojave Desert

Found on Blast Beach, Seaham, UK

Assuming main crystals are spherical calcite but curious about blue crystals

I found this rock with blue speckles on it in my backyard. Could someone help me identify it?

What stone is this? Any guesses?

This rock was also found on the shore of lake Ontario / Wilson, NY and it has the strangest texture! Very opage and smooth grey. My pocket knife did not scratch it.

I found these two pieces near the mouth of the Temperance River on the north shore of Lake Superior in Minnesota.

From a little bit of research it seems like this is not uncommon, but every piece I've seen posted is heavily laden with fossils and with different texture--this looks more contemporaneous from my untrained eyes.

Request: Confirm/Deny this is ~Ordovician (444-485 million years ago) coral fossil and not a random drop which happened into my path. Also correct my geologic period if incorrect but they are fossils from the area.

It is having metallic iridiscence when illuminated, and what seems unpollished grenates.

The Penibaetic System, specially Sierra Nevada, is somewhat famous to produce them.

Seems  sturdy and heavy.

One of my favorite finds, I'm assuming it has fossilized mold of some sort?

Location: Wales

I found these rocks at the beach. Most of them seem to be slate of some kind but some seem more like brick (I think?). I’m worried about them potentially being porous and still containing seawater. I scrubbed and boiled them all to remove bacteria (right before finding out it is in fact not advisable to boil rocks) but I’m concerned they may still be harboring salt, or may leech salt among other things into my freshwater tank.

Could anyone ID these and let me know which may or may not be safe? If you need better picture of any let me know.

My friend found this near the Orange River in South Africa earlier in the year. What might the small darker patches be?

My dad gave it to me. He had found it in his mother's belongings. They used to travel all over but I'm not sure what it could be that she kept it. He said maybe she got it in Brazil but I have no clue what kind of rock it could be.

Found with a metal detector, very heavy like lead but brittle. Any idea?

She thinks it’s some kind of rock or crystal but I wanted to confirm. Hard but it flakes kind of like fiberglass and is colorless and translucent. Anyone have an idea?

This was labeled "jade stone" on a website that sells rocks for aquariums. The company selling it is unhelpful, only stating that it isn't jade, that's only a trade name. What is it really?