Please help - what rock is this?

[ramen lover]

Hi all- I got this rock for really cheap from a landscape garden place.

it is white and has sparkles in it. it is very hard to break (tried to use a hammer and a sledge hammer and all it would do is break little pieces off of it).

when i put vinegar on it, nothing happened. I went to the store and got some ph down and when i put ph down on it, i could hear it fizz a little, but it wasn't fizzing a lot/foaming. i could only hear it a little. even if it fizzes a little is that bad? should the rock not fizz at all?

[CatB]

it looks like quartz. what is your pH? a little fizzing shouldn't raise it that much, you could always soak them in a bucket of water and test like a day later to check...

[ramen lover]

oh ok i wasn't sure if any fizzing meant that i couldn't use it at all.. or if a little fizzing was okay. when i cover it with ph down, i can hear the fizzing when i put my ear up to it, but i don't see bubbles everywhere or anything.. the rocks are huge.. i guess i might have to try to break a piece off to see if i can test the ph

[proaudio55]

fizzing means there's a carbonate mineral in there. The best way to check a rock is to put it into a 5 gallon bucket of water and crash the Ph by adding a cup of vinegar to it. Let the rock & water sit for a day or two and recheck your Ph.
~If Ph is still pegged off the scale at <6, you've got a good stable rock.
~If Ph "magically" drifted to 7+, don't use that rock for anything other than a rift lake cichlid tank.


Limestone & dolomite are really common rock in many areas but they won't work in a tank.
#1. They shed calcium & magnesium into the water (this is the hardness that most tropical fish don't like)
#2. They put carbonate into the water which neutralizes acid and raises the Ph....

carbonate plus acid ion = water and Carbon Dioxide
CO3 combines with (2)H+ = H20 and CO2

[PlantedRich]

You've just run into one of the follies in the fishkeeping hobby. We seem to want to have "rules" rather than think. The rules often only apply when you have the same setup as the rule used. Rocks that fizz are not bad! It just takes some thought on why they fizz.
If you take any alkaline item like limestone and pour an acid on it, it may fizz. Just junior high science. The stronger the acid, the stronger the reaction. Does that make it bad? Depends on what you are doing in YOUR tank, not what the rulemaker was doing in HIS tank.
If you have acidic water and want to raise it to a higher PH, limestone or coral may be just what you want. If you have high PH water and want to use limestone, you may see no change at all. If you have neutral water and want to use the rock you have, it is a matter of knowing it MAY change your water or may not. If you put it in and monitor the PH, then you will know what it is doing. All the other is theory which may or may not work in your tank and the way you operate. If you want African cichlids, you will like the results. If you want soft water fish, you may not.

[ramen lover]

i broke two small pieces off last night with a sledgehammer and put them in a glass of water. i also used a control and put water in another glass.. this morning, i checked the pH level of the water with nothing in it and the water with the rocks in it. both were at around pH of about 7.4. .. so right now it doesn't look like the rocks are affecting the water pH level.. but it has only been about 10 hours. i'll keep checking for the next few days.

[ramen lover]

Originally Posted by proaudio55

fizzing means there's a carbonate mineral in there. The best way to check a rock is to put it into a 5 gallon bucket of water and crash the Ph by adding a cup of vinegar to it. Let the rock & water sit for a day or two and recheck your Ph.
~If Ph is still pegged off the scale at <6, you've got a good stable rock.
~If Ph "magically" drifted to 7+, don't use that rock for anything other than a rift lake cichlid tank.


Limestone & dolomite are really common rock in many areas but they won't work in a tank.
#1. They shed calcium & magnesium into the water (this is the hardness that most tropical fish don't like)
#2. They put carbonate into the water which neutralizes acid and raises the Ph....

carbonate plus acid ion = water and Carbon Dioxide
CO3 combines with (2)H+ = H20 and CO2

thanks! i will try this test as well. just put a large rock in a bucket and added like 1 or 1 & 1/2 cups of vinegar. tested the initial ph.. it's a 6.0. will re-check in 1-2 days to see if it moves to 7.0+ or if it stays at around 6.0

[Diana]

Ditto Planted Rich- Rocks that might not be useful in an acidic, soft water tank can be perfect in a hard water tank.
Let us know the results, those look like nice rocks. Are you able to find some that are small enough to fit in the tank?

[PlantedRich]

When you try to break a rock, there may be a trick to getting what you want. Rocks are often very hard but brittle. Trying to smash it may do just that and you get crumbles. To break rocks where you want, it often takes a repeated lighter touch. If you can get something heavy duty metal like a chisel or even a big old screwdriver, you can often score the rock to break correctly. Start out tapping in a line and then just keep hitting in the same place over and over. The vibration will make the rock break along the line. Mini- jackhammer rather than a crusher.

[proaudio55]

I actually fought with this issue when I first got into fish keeping. I bought a used tank out of the classified pages in the newspaper (I'm dating myself here ).

I was just a kid and a total n00b... every time I tried to lower the Ph with "Ph Down" the tank would bounce right back to 7.6. I expended the whole bottle of "ph down" into this 30 gallon tank; I had no lasting results and I got really frustrated. At the time there weren't any fish to worry about, so I decided to "take the gloves off" and started using jugs of vinegar from the grocery store. After I poured God-only-knows how many gallons of white vinegar into this tank. I eventually figured out that the previous owner had used landscaping pea gravel for the substrate!?!

Anyways . . . that was one of my early fish keeping screw-ups: I learned my lesson: Be wary of any rock.

And as I stated initially, carbonate rocks may be fine for certain biotope setups (particularly rift lake cichlids). But IMHO, totally inert rocks are always preferred because they are safe with any setup, any water chemistry, and any tank.

[ramen lover]

i've been running tests on these the past few days and here are my results so far..

1) small clumps inside of glass cup with water - regular pH of my water is 7.4.. and the cup with the rocks in it is also 7.4.

2) put a large boulder inside a 5 gallon bucket of water.. added almost 2 cups of distilled vinegar. tested pH at the beginning.. was 6.0. tested pH again today (1 day later) still at 6.0.

3) put some nitrate test #1 directly on one of the rocks. saw some very tiny bubbles. not many. it didn't fizz really and didn't foam.

with these results.. if they stay the same in about another day..d o you think they are okay to use?

[proaudio55]

From what you're describing, the rock sounds inert to me. . .

You've not really elaborated on what water conditions you're going to be shooting for in the tank. Typically tropical fish prefer soft, faintly acidic water. If you have a hard time maintaining that and the water keeps drifting basic & hard, you'll need to re-examine the rocks. Otherwise, it sounds like you've got a winner!

(It sort of looks like quartzite (which is inert), but it's been years since I took mineralogy with Dr. Donovan @ Winona State University )

[ramen lover]

Originally Posted by proaudio55

From what you're describing, the rock sounds inert to me. . .

You've not really elaborated on what water conditions you're going to be shooting for in the tank. Typically tropical fish prefer soft, faintly acidic water. If you have a hard time maintaining that and the water keeps drifting basic & hard, you'll need to re-examine the rocks. Otherwise, it sounds like you've got a winner!

(It sort of looks like quartzite (which is inert), but it's been years since I took mineralogy with Dr. Donovan @ Winona State University )

Sorry I plan on doing a simple aquascape with rocks, eco-complete, and a large school of cardinal or neon tetras.. and probably some shrimp. think it would be okay to use these rocks? im going to test again when i get home from work to see if the pH has changed in any of my tests.. so far the rocks haven't changed the pH

[TexasCichlid]

Originally Posted by proaudio55

Limestone & dolomite are really common rock in many areas but they won't work in a tank.

Not true at all. Limestone is commonly used in African Cichlid tanks. Limestone is also commonly used in planted tanks in the form of Seiryu stones.

I second that it appears to be quartzite or some other mafic metamorphic rock of a similar nature. The slight fizz you are hearing may be from calcite inclusions caused by fluid migration. Not uncommon and not dangerous.

I use Seiryu with shrimp, rasboras and otos with no ill effect, and it raises my TDS by 30 points on a daily basis.

[ramen lover]

Originally Posted by TexasCichlid

Not true at all. Limestone is commonly used in African Cichlid tanks. Limestone is also commonly used in planted tanks in the form of Seiryu stones.

I second that it appears to be quartzite or some other mafic metamorphic rock of a similar nature. The slight fizz you are hearing may be from calcite inclusions caused by fluid migration. Not uncommon and not dangerous.

I use Seiryu with shrimp, rasboras and otos with no ill effect, and it raises my TDS by 30 points on a daily basis.

Thank you! I think it is quartzite. I researched it about it and it looks like quartzite. It is not powdery at all. It barely bubbles.. even with nitrate test #1 put directly on it. i've had rocks in water already for 3 days or so.. pH is still the same as tap water (7.4). and in the bucket with a cup of vinegar.. the pH is still 6.0. it doesn't look like it's affecting the pH.

i'll be using these rocks with tetras.. probably cardinal, neon, or rummynose tetras. they will be in my 55gallon tank.