# Rock identification



## mantiz (Oct 14, 2012)

Hi, I am in the process of aquascaping and was wondering if someone could identify the type of rocks that were given to me. They almost look like lava to me but have texture like petrified wood. They are about 12 inches in size and have passed the vinegar test.

https://docs.google.com/open?id=0B0OTh8zKB00pVDZacE9xeGl1Z0E
https://docs.google.com/open?id=0B0OTh8zKB00pR3dHcFNiNUlKSzg


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## Fishfur (Mar 4, 2012)

It is, unfortunately, difficult to tell from these pics. Though they are nice and crisp and clear, the background colour makes it hard to see the rock colour and there are strong shadows which are also obscuring the colour and some texture on the stones. 

If you could take new pics, best would be a nice neutral background. Flat black or flat white would be great.. I like to use old towels because they don't reflect any light to speak of and most of us have a white towel, or at least a pale one. Or some rags or even paper towels.

Try to avoid the shadows, I know that can be difficult, but if you take the pics outside in daylight, you won't need the flash, and you'll get a much better idea of the true colours and texture. Also try for close up views on each one, to show both the texture and any variations in colours, or striations. The camera or lens you have will govern how close up you can get, but it will help even if it's not a real macro shot.

So many kinds of rocks can look very similar, and I'm no expert, but one possible that came to mind looking at your pics was petrified wood. But better photos would help a lot. If it IS petrified wood, you should test it with something stronger than vinegar. It often has pockets or veins of calcium in it, which vinegar may not show up. My preferred 'go to' old reliable for rock testing is CLR. CLR is safe, but the acid in it is much stronger than vinegar and meant to dissolve calcium particularly. You get super fast results as well.

They look quite coarse in texture, so I'll ask if they are a reddish colour, like really old rust, rather light for their size, very porous and it's pretty easy to crumble a bit off an edge ? If yes, it's lava rock, which is usually fine so far as calcium goes, but can damage some fish because of the coarseness. Depends what you plan to have in the tank. 

And if only a very small area on a given rock reacts you may still be able to use it. Sometimes you can break the rock, and only use the part that isn't showing a reaction. Have to hope you like the new shapes though.. hard to control how they come out in many rocks. Wear safety glasses and use a hammer and cold chisel if you're going to try breaking rocks, chips can fly everywhere ! But if the area that is showing a reaction isn't very big, or there's just not much of it in the whole rock, I'd use them as they are, because I have hard water and Ph over 7 in most of my tanks. Tiny bits in a large rock are unlikely to affect water chemistry in such conditions.

If you want to be certain, do the CLR test. If a rock passes the vinegar test, but then fails a CLR test, then at least you know the calcium content is not very high.. if it was, the vinegar would have shown it up. So it depends what your tank water conditions are. Should be just fine to use in most tanks with fish or shrimp that like hard water and a Ph over 7. But not a great choice if you were going for soft, acidic water in your tank, with the Ph below 7.

Hope you find out what they are... if you can, new pics will help.


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## mantiz (Oct 14, 2012)

Here are some new pics. I hope they are a little better! Sorry but the rocks are wet now. I was bleaching them to kill any hitchhikers.

https://docs.google.com/open?id=0B0OTh8zKB00pMmZEYXhsVFBhX0E
https://docs.google.com/open?id=0B0OTh8zKB00peUZkUTMtV1Nyc2M
https://docs.google.com/open?id=0B0OTh8zKB00pRkFJbWhYVkgzSnM

They are a dark brown and a little bit crumbly if i try hard enough around the edges. and are heavy. I wouldn't expect petrified wood to be so.

I will be using them in a cichlid tank so a higher PH is a good thing IMHO. I will go out and get some CLR to test it again.

The person that was using the rocks before me didn't seem to have any problems using them.

EDIT: After looking online it almost looks like Tuffa Rock but darker. Petrified wood doesn't seem to have as many pockets in it. This almost looks volcanic in some places and granite like in others.


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## Kooka (Feb 8, 2011)

So if you're gonna use them in a cichlid tank, why test them with vinegar?

The vinegar test is used to determine whether the calcium carbonate in rocks like limestone will react. If you want harder water for what I assume are african rift lake cichlids, I wouldn't care if it was limestone or not.

The rocks you have in the pics are some sort of igneous rock, due to their vesicular appearance and reddish/brownish color. They could also be petrified wood, which is heavy (I know since I've handled lots) and the texture and patterning is also very reminiscent of it.


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## bob123 (Dec 31, 2009)

They look very much like petrified wood to me.


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## JayPetro (Feb 8, 2012)

Its difficult to tell without handling the rocks but they do look volcanic in nature...quite possibly basalt. Although the first rock seems a little more foliated(layered) which basalt doesn't normally show. Tuff or some other form of volcanic ash rock maybe be the case as well. Tuff is sand sized particles and smaller while other ash rocks can be made of rock fragments of whatever the surrounding geology is composed of...which may be why you see more than one type of rock in there. I have studied and looked and more rocks than imaginable as I completed my university degree in Geology. If you REALLY want to know I drive through Markham every day to and from work and could confirm them for you. Many/most Volcanic rocks tend to contain phosphate which can lead to algae problems but with regular water changes that shouldn't be a problem as it would only release it very very slowly. Not ideal for reef tanks but may be okay for cichlids. Hope this helps.
Jay


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## Fishfur (Mar 4, 2012)

I think that new pic is petrified wood too. Nice piece of rock. 

The trouble with petrified wood is that it can show extreme variance in its appearance. Its appearance depends on a lot of different factors, during a very slow process, as water infiltrates the wood, then leaves it's mineral load behind as it evaporates or moves on, which fills up the channels in the wood tissue until eventually wood becomes stone. You get so many variables - type of wood, condition the wood was in, where it was located, what minerals were in the water, as they are responsible for many of the colour variations; whether it remained buried or became exposed and was weathered by the elements.

Some pieces can be crumbly, some can be almost polished looking. Some are smooth as can be, some very coarse. They all tend to be very heavy for their size - it can surprise you when you pick one up. Some clearly show the original wood grain, some others you can't see it at all. 

They are very cool rocks. I love the way they look and I've lost track of how many pieces of the stuff I have acquired here and there. I used to use it for bonsai displays, now some is in my tanks, where the water makes it look even prettier.

Kooka's quite right.. for a cichlid tank, calcium leaching isn't an issue. But I test all my rocks when I get them simply because I am curious to see if they react, and how much. My little science experiment !


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## Fishfur (Mar 4, 2012)

Nothing like hearing from an expert on the subject ! Now I'm really curious to know what they are and they aren't even my rocks .


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## pyrrolin (Jan 11, 2012)

Wow, nice rocks, I would love to have these in an aquarium


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## Jamblor (Dec 21, 2010)

Since it's about rocks I must chime in lol.

As with everyone, it's pretty hard to tell from the picture.

But you said it's heavy? Well i guess in comparison to what. But if the consensus is that its a tuff wouldn't it be lighter than the average rock? 
And if we are saying it's a basalt, I can't ever remember seeing a brown basalt, unless it has been altered. Thoughts?

Take Jay's word over mine though, I'm in my last year of my geology undergrad.

By the way, Jay would you happen to work for a geophysics company out that way?


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## mantiz (Oct 14, 2012)

Thanks everyone for all of the input. I am going with petrified wood on this one too. Here are a couple of closeups of the "grain" when dry if anyone is interested:

https://docs.google.com/open?id=0B0OTh8zKB00paUJBbXJXaG1lNG8
https://docs.google.com/open?id=0B0OTh8zKB00pODdwNXJtaHpYQUU
https://docs.google.com/open?id=0B0OTh8zKB00pajJxSWtPWXBNdFk
https://docs.google.com/open?id=0B0OTh8zKB00pOHFFNWtYcS1yd2c
https://docs.google.com/open?id=0B0OTh8zKB00pTWdQaDVfRW5EUHM
https://docs.google.com/open?id=0B0OTh8zKB00paVdNSnp6NW8yQWs

Please excuse the bad photography. I have really bad lighting in my house only a telephoto lens and tripod that can come close to macro shooting.

I am putting them into the tank anyway as they look good when wet.


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## Jamblor (Dec 21, 2010)

Sounds good, and from those pics they definitely do not look volcanic. 

Alsmost look like a weathered out gneiss or some other foliated met. rock


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## OneLastDecree (Nov 13, 2012)

Those rocks are insane. 
I want them. 

You're very lucky to have them in your tank.


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## mantiz (Oct 14, 2012)

Just working on the aquascaping now but here are the rocks in the tank.

https://docs.google.com/open?id=0B0OTh8zKB00pcUUzdE1hZjAzUW8
https://docs.google.com/open?id=0B0OTh8zKB00pWm9ySTBqV24xS00
https://docs.google.com/open?id=0B0OTh8zKB00pQkNYZVRDYzU1cTQ

I think they look pretty good... Now I wish I had a lot more of them as they don't match the other rocks i have!


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## OneLastDecree (Nov 13, 2012)

Looks fantastic. 
Still jealous of your Rocks.


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