obsidian in a reef tank

[tlsrcs]

i recently bought a dew pounds of crushed obsidian from aqua imports the other day because it was black.....anyways the guy told me it was completly inert so i had nothing to worry about. did i make a mistake?

 

[Heffe01]

I would think you will be fine if it is mixed with other sand. I would do a vinigar test to make sure it is pure obsidium because other minerals could be found inside it. If you see it reacting then I wouldnt use it.

Here are some of the other cons to it though:

Doesn't buffer like aragonite does (Which if you added just a little to your aragonite you should be fine)
Scratches glass if caught up in a mag float
Can grow GHA on it

I have used it before in the past...mixed in with fiji pink aragonite. I loved the look at first, but then I started having little pieces of GHA grow on it. Wasnt the rocks fualt because it was in my 29g biocube which I mostly neglected.