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Cichlabxr

Rocks: Discoloration (002)

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I have some rock which I believed to be marble. It is from Albury-Wodonga.

It has all the appearances of Marble ( I'm no Geologist). Since being in the tank Water ph6.5 -7.0 it is started to turn green in places. My first thought was that it contained copper. Any ideas?

Thanks Martin

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Hi Martin,

Can you post a picture up? I need a lot more info than you've given to work out what it might be. How about colour, inclusions, hardness (as in 'breakability'), texture, uniformity/layers/veins etc. I spent a bit of time around Albury/Wodonga and don't remember seeing any 'marble-like' rock. The pH stated is too low for a carbonate based rock.

merjo smile.gif

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Merjo I read it to mean that Martin is asking if the pH of the water maybe affected the stone? Not the pH of the stone itself?

My gut instinct is telling me algae, beneath the surface, through some kind of imperfections in the surface?

Is that possible/likely? dntknw.gif

ps. Listen to merjo, she's a rock-nerd! yes.gif

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I always remember being in Janolen (dont know about that spelling) caves as a kid and being told that the acids from our fingers turn the rock green. Could it be a similar sort of situation in your tank? Perhaps the PH of the water is affecting the rock a la janolan caves style? Or perhaps chemicals present in the water, be that oils, proteins etc. may be eating away at it in some sense?

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Try again. Maybe its quartz rolleyes.gif so my wife reckons. As you can see (hopefully) the smaller piece is going green.

It was in a tank with a lot of wood and the ph was 6.5 most of the time.

user posted image

user posted image

user posted image

The other 2 pieces also have some tinge of green. I was thinking this was granite.

My question, badly put originally, is the rock reacting with the slightly acidic and soft water.

Regards Martin

Edited by Cichlabxr

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Okies...the two grey and white rocks at the back are granite. They are basically quartz, biotite and feldspar (are there greyish/blue inclusions?? because it looks very like some beautiful blue plag. based granite I scabbed from Torrumbury Weir). If it is blue plag. are you calling it "green"? Colours intensify in water. The white pieces are fluval affected/worn quartz. Neither will have an effect on the pH or hardness of your tank. As for the greenish colouration happening in the tank; if it isn't algae then I cannot think what minerals would be causing it.

merjo smile.gif

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Thanks merjo,

Yes there are greyish/blue inclusions. I actually have a larger piece(somewhere) which looks rather pink but the greyish/blue becomes more obvious under the water.

I will now put them back in the tank. Thanks for the help.

Regards Martin

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