Is this oxidation on rock?

[RedFrog211]

I want to move around my rock work a bit. I have an “established” nano reef (20g, 5m old) and I want to replace a large rock that just doesn’t go well. It’s probably 40% of the overall rock work, and I have 3 smaller pieces I want to replace it with. While scrubbing them, I noticed one that appears to have oxidation on the surface. The picture I’ll attach is after it’s been scrubbed in hot water and left to dry. Does it appear to be just coloration, or is it true oxidation? Is there a simple way to test? I just wanted to run it by the pros before adding it- this is my first time messing with aquascape, and I’d hate to introduce iron or cause a massive ammonia spike. With that being said, I’ll let the rocks sit in the tank for a couple days and introduce bacteria before removing the current rock to prevent a spike.

 

[Casket_Case]

I’m not a pro but maybe you can dremel it off and see if it removes... if it removes it probably just got rust on it from something else.

 

[Casket_Case]

I’m not a pro but maybe you can dremel it off and see if it removes... if it removes it probably just got rust on it from something else.

Just make sure all the red goes away

 

[RedFrog211]

I’m not a pro but maybe you can dremel it off and see if it removes... if it removes it probably just got rust on it from something else.

I scrubbed it under hot water then let it soak in RO water for 48 hours- now it’s in the tank, so let’s hope it’s not iron!! Haha

 

[Casket_Case]

I scrubbed it under hot water then let it soak in RO water for 48 hours- now it’s in the tank, so let’s hope it’s not iron!! Haha

I wouldn’t recommend putting something you can’t identify in your tank, that’s how you lose corals and fish really quick... it never hurts to wait for confirmation that what you’re doing is safe