# bad sign for metal in rocks?



## sandiegofishy (Jun 23, 2014)

I picked up some new rock at a local supply store, its called "Gray Cresta". The description from the supply store's website is always pasted below. Is the brown/rust sides a bad sign for metal in the rock? Not all of them have it, but some do. I'm not worried if this isn't a good choice, i only paid $16 for all these rocks.

Cresta
Stormy charcoals battle with the serene and venerable ashen tones. The color fusion of this boulder is bold, intrepid, and powerful. Size: boulders and rubble
Color: Rich gray base overlaid with a rust brown finish
Geology: Granitic in origin


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## somebody (May 13, 2014)

I'm no geologist but I would say so. Scrub them clean then spray them with salt water to a soak then let them air dry. I work offshore and saltwater is pain. Any exposed metal (not aluminum, etc.) on the boat will rust in a short amount of time.


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## sandiegofishy (Jun 23, 2014)

any other opinions? Finished painting background black and would like to start my rockwork today. If these rocks look OK or not please let me know


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## OllieNZ (Apr 18, 2014)

My rocks look similar and tbh I didn't give it a second thought. If it's a hard water tank you'll be fine.


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## anthraxx4200 (Aug 16, 2012)

honestly id say its more likely a staining process from some other materials on site where its collected. the real issue i would have with any conglomerate rock, is if its an ore bearing rock. (IE small tiny bits of lets say silver or something else in it) doesnt appear that you have anything to worry about tho, its probably just some staining on the rock like i said. if your really concerned you could keep some of it submerged in a bucket for a few days and see if the rust spreads. itll rub off on the bucket and just get everywhere


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## iridextr (Feb 8, 2013)

you'll be alright as long as it's not copper or a couple other metals/minerals that I can't remember off the top of my head. If it's iron it won't be toxic to the fish, your rocks are fine. I use basalt trap rocks in my tanks and they always have veins of other metals/minerals running through them, it's beautiful!


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