Safe Rocks (toxicity among other things)

[Jynxx25]

Hello all.

I would like to get members' feedback on types of rocks to use inside a terrarium for basking purposes. I know about serialization (i.e. boiling rocks and being precautious of them exploding). But what about the type of rock or even minerals?

For example, I researched a few rock and mineral sites that state certain rocks and minerals may contain lead, copper, and other elements that may be harmful to a snake or reptile; either from contact or even accidental ingestion (i.e. a rodent bites into the rock and then the python eats the rodent).

Two red flags is that if the rock has green or even blue hues in the color, it may contain copper. Another flag was shiny elements may be a metal.

Any recommendations? I was thinking slate, but they tend to be jagged.

I have a few samples of flat river rock that is smooth. However, I have since ran out.

[Jynxx25]

I viewed a video from King of DIY, it is for aquariums, but if they are safe for aqua life, then it should be safe for reptiles. But he does not cover types of rocks that are known to have or not have toxic elements.