This stone in my tank?

I bought it from a store with other mineral rocks. the guy said it was a a type of quartz

 

Ah, that's amethyst. The crystal itself is probably safe, but I would be concerned about what it's attached to.

 

It is attached to onyx, both of which are fishsafe. I have been using both minerals in my tanks for over 30 years.

 

I love it

 

Ooh. I thin I'm getting me some decorative amethyst then <3

 

I have a bunch of those stones where the inside is spiky white crystals, and the outside is a bright color like blue or purple...I'm sure there's a fancy term, haha. I never thought of using them, thanks for the idea

 

Ya I have had this laying around for a while. I thought it would look nice. So does it do anything beneficial for your water?

 

Ooh. I thin I'm getting me some decorative amethyst then <3

I got it for 4 dollars it is inexpensive