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Well I found some huge chunks of quartz at my parent's house and went ahead and grabbed a few. I've heard that it's 99% inert in most cases, and I did not see anything else on the rocks besides quartz so I boiled it and threw it in the tank. (Yes I know I should have probably put it in a bucket of water and tested the parameters before I took the plunge, but I'm very impulsive.) :icon_redf

I was just curious as to whether people have had any issues using quartz in their tanks, or if there's anything I should be concerned with.

Oh, and it looks really cool under my moonlights!

 

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Speaking as a geologist with some background in geochemistry - at aquarium conditions, quartz is insoluble for all practical puposes. In any case, any water but rainwater would already be at saturation point for quartz, it is a ubiquitouos mineral.

You ask if any rocks or mnerals (rocks are assemblages of minerals, BTW) will lower pH - the answer is yes. Any that contain pyrite, a common mineral will do that; the pyrite breaks down to form sulfuric acid. Actually, another iron sulfide, marcasite - also pretty common but much less so than pyrite - is more of a problem in that regard, it is not stable in oxidizing environments. Pyrite, also knows as fool's gold, is usually well crystallized, forming cubic crystals that are metallic yellow; marcasite is silvery yellow and more likely to be found ih coal bearing rocks, a bad bet for aquaria anyway! Weathered pyrite forms rust stains.

BTW, some good tests for quartz: it readily scratches steel, and breaks with a fracture that resembles the lines on a clam shell Thatfracture is best seen on a crstal rather than on massive quartz.
 

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I cant argue with the expert here, and if quartz was harmful I don't think the glass tank itself would be safe, right? Isnt quartz a more stable "form" of silicate?I have read the opinion that using silica/quartz sand in a tank causes diatom/brown algae growth, but I believe that is a unproven assumption considering silicates are not the limiting factor of diatom growth and if they were then the glass aquarium would supply them with an endless buffet. If I am mistake I would love to know the facts. Holy cow, its nice to have a geologist sharing with us, thank you. Can you go creeking on my property to ID any rocks I might find? Seriously,any recomendations on a book or guide for us(laymen) to use for deterime rock type? No phd required
 

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I was thinking the other day that I'd like to use some reasonable sized clear quartz crystals in a tank scape along with moss balls and rocks...

I've seen rose quartz sold for fish tanks, I bought a big chunk for £4 ! That would have cost me about £10-15 in a new age store!!!!! I didnt put it in my tank though, it's on one of my shelves with the other many many crystals.

I think Selenite would look great but I read it's friable(sp)? As in it dissolves in water/liquid?
 

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Seasofchz, pay my way to and from Indiana and I'd be glad to ID the rocks in your area! Failing that, the Audubon Society has a guidebook to rocks and minerals, and more cheaply there is the Golden Nature Guide. In Indiana, the rocks would be all sedimentary except in glacial moraines. Not all limestones will fizz with vinegar. Many are partially or even mostly composed of dolomite, which is calcium magnesium carbonate, and are properly called dolostone. They will fizz slowly in cold hydrochloric (muriatic) acid and rapidly in warm hydrochloric acid. Pure or nearly pure dolostone is usually a light to medium gray with a sugary texture, and seldom has fossils. Cavities may display saddle-shaped crystals, which are white to pink with a pearly luster. It is as bad as limestone as far as being in an aquarium.

Honeythorn, selenite is a form of gypsum, which is calcium sulfate and is ratjer soluble. DO NOT use it in a tank!!!
 

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Ah so it does dissolve! Don't worry I wasn't going to use any in tanks, I like it too much on my shelf and I like my fish and plants alive!!! The rose quartz will also stay on the shelf haha, a pink tank is not my style at all >.< I have never studied geology ( I wish I had ) but I have a great interest in crystals and own many ( as well as crystal and gemstone jewellery, my Seraphinite pendant is my current favourite)

Good to know Quartz is safe though, I have some ideas for that, and agate also? Hmmm......*ponders obtaining a lump of moss agate...*
 

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I did use some quarts crystals on my tank for a change and tried to mimic someones else scape in this tank. Nothing bad or casualties happened so far:icon_smil.

and this small gallon tank
 

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clarification please

Mosasaur, what part of this was aimed at me. I want to clarify, please don’t think that I am being smart or rude. I want to make sure that I understand you. I never meant to imply that the “vinegar test” would prove that a rock is safe. Did I say that? I thought we were talking about quartz so now I am confused as to if you were just stating facts for everyone or me specifically ."Not all limestones will fizz with vinegar. Many are partially or even mostly composed of dolomite, which is calcium magnesium carbonate, and are properly called dolostone. They will fizz slowly in cold hydrochloric (muriatic) acid and rapidly in warm hydrochloric acid. Pure or nearly pure dolostone is usually a light to medium gray with a sugary texture, and seldom has fossils. Cavities may display saddle-shaped crystals, which are white to pink with a pearly luster. It is as bad as limestone as far as being in an aquarium." I would then add that dolomite and calcium carbonate (limestone/aragonite) are utilized for some marine tanks as well as African cichlid tanks. Of course, in a planted tank it wouldn’t be advisable. We were talking about quartz, so now I am unsure if I have a grasp on this. Let me ask you this, does the infused magnesium of dolomite make it much harder to detect than arag/limestone? I read (TFH) that one has crystals that are orthorhombic and the other rhombihedral(spelling?) like comparing graphite with diamonds in terms of what created the stability of similar minerals due to crystal forms. There are all kinds of fossils in Indiana’s rocks, sedimentary rock is everywhere here, but I have never been told that it was the only rock here, like you said glacial dropstones, moraines???. I hope you don’t think I am clueless, I value expert info and I thank you for clarifying.
 
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