# Inert Stones List?



## jagerlite

Granite, slate, lava rock....Would be a good list to reference when doing build outs


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## lochaber

Really rough generalization: igneous and metamorphic rocks are usually fine, sedimentary can be iffy, and avoid anything with metallic bits or bright colors.

Usually people are concerned with a rock leaching minerals into the water, and affecting pH/hardness - it's usually carbonates that are the most commonly found rocks that do this.

Part of this is because carbonate rocks are pretty common, and because of the ease of weathering/dissolution, they will often end up being really interesting looking (seiryu stones, etc.)

The vinegar/acid test isn't real reliable - it usually won't work on dolomitic stones. Although it's not as specific, try scratching the rocks with something pointy and steel - a nail, knife blade, dentist's pick, etc. If it won't scratch, it's probably safe (at least it's not a carbonate - they are all pretty soft), although there are some soft rocks that are safe.

If you have access to a local college/university library, see if you can take a look at some of the geologic maps, often they will show where a given bedrock formation surfaces, and that can be used to help guess the composition of the rock (though, places where rocks are transported, like stream beds, hillsides, etc., can be rather messy)


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## snowmonkey

Just from my experience at a LFS, the ones that we had tested and found to be safe for freshwater were
Lava Rock, both black and red
Slate
Most Feldspars, possibly some exceptions
Granite( but not marble)
Quartz (if there is not iron in with it)
Rocky Mountain Rainbow Rock
Green Serpentine (My personal favorite)
Silver Schist( gets a bit flaky but if you get the loose stuff off before putting it in the tank its not bad)
Obsidian (if you can get a hold of it)

Im sure this isnt a complete list, and as in most -ologies, mineralogy has its many exceptions. If you live in the southern midwest, a man named Dan Ryder drives his truck all over the place selling his rocks and rootwood pieces. We trust him with our rock sales and he hasn't let us down so far.


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## roadmaster

Used a lot of flagstone in cichlid tank's , and collected many hard, round,smooth riverstones from stream's I fish, and local landscaping stores.
Easy to test them with bucket of water with known GH,pH.
If after adding the rock and testing the next day the pH,GH,rises... then you'll know .


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## Cypranid Kid

Great information all. Thanks


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## lochaber

snowmonkey said:


> Just from my experience at a LFS, the ones that we had tested and found to be safe for freshwater were
> Lava Rock, both black and red
> Slate
> Most Feldspars, possibly some exceptions
> Granite( but not marble)
> Quartz (if there is not iron in with it)
> Rocky Mountain Rainbow Rock
> Green Serpentine (My personal favorite)
> Silver Schist( gets a bit flaky but if you get the loose stuff off before putting it in the tank its not bad)
> Obsidian (if you can get a hold of it)
> 
> Im sure this isnt a complete list, and as in most -ologies, mineralogy has its many exceptions. If you live in the southern midwest, a man named Dan Ryder drives his truck all over the place selling his rocks and rootwood pieces. We trust him with our rock sales and he hasn't let us down so far.



I'm curious about your experiences with the serpentine - I remember it coming up in biology classes quite a bit, as soils derived from serpentine bedrocks tend to be fairly toxic to most plants, and about the only plants that grow in serpentine soils are those specially adapted to it. Also, serpentine tends to have higher concentrations of various heavy metals that can be toxic (part of what makes it pretty).


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## Asu1776

Went to the fish store to buy these nice looking pagoda stones. Was told it was inert and wouldn't affect water params, but did my research, did the PH down test, and my new rocks fizzed away. Sigh. No returns on rocks. I was irritated for a while, but then I remembered my water is extremely soft (1-2 dkh) and in the time it would take for the carbonate to dissolve and raise KH super high, I would have done several weekly water changes. By the way, I saw on forums that stones leaching minerals into the water is bad for shrimp, but don't they need calcium carbonate anyway to form their shells?


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## ravensgate

Asu1776 said:


> . By the way, I saw on forums that stones leaching minerals into the water is bad for shrimp, but don't they need calcium carbonate anyway to form their shells?


It has to do with parameters changing. Shrimp require stable params. Leeching rocks can affect pH, KH, and GH...you don't want those things being changed much when dealing with shrimp. Makes for unstable environment.


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## snowmonkey

lochaber said:


> I'm curious about your experiences with the serpentine - I remember it coming up in biology classes quite a bit, as soils derived from serpentine bedrocks tend to be fairly toxic to most plants, and about the only plants that grow in serpentine soils are those specially adapted to it. Also, serpentine tends to have higher concentrations of various heavy metals that can be toxic (part of what makes it pretty).


Most of my knowledge about it comes from our rockhound, Dan Ryder. He procures rock and rootwood pieces for most of the southern Midwest. I asked him about it because it does occasionally bubble a tiny amount when put into a tank, but he explained that all of the heavy metals, mostly are trapped in the structure. He has been selling it as inert for years and has never heard any problems with it. almost all of the hardscape i have in my 10g planted is green serpetinite(the rock form of the mineral) and ive had no problems so far. unfortunatly he only comes around every few months and his last visit was two weeks ago, so i have a while until i can ask him in more detail. Since you brought it up ive gotten suspicious of it and have been trying to do more research on it. what ive found so far is few and far between, not much to do with it being inert in water or not. 

Ill post back with what i find out, maybe ill give Dan a call.


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## Diana

Here is more about serpentine rock:
http://en.wikipedia.org/wiki/Serpentine_group

There are several different types of serpentine. 
The hard greenish variety found on Mount Diablo and other locations in California is the parent rock of serpentine soils, high Mg and low P, K and Ca. Special plant communities grow on exposed outcroppings of serpentine soils. 

Making soil out of rock takes millions of years. There are plenty of visible (exposed to wind and rain) rocks among the serpentine areas I am familiar with. If these rocks break down in an aquarium they would have to be a lot more active. 

Reading through the details I see that serpentine is listed as fairly soft, and susceptible to acids. 
But does this mean it is as highly active as many of the calcium carbonate types of rock? 

I would test it with GH, KH, pH, TDS and see what happens in acidic water over at least a week (weekly water changes) but perhaps run it out to a month worth of testing, if the rock is slow reacting. 

Other rocks that I have found safe:
Most rocks used for landscape, and sold in the San Francisco Bay Area.
EXCEPT: rocks from calcium carbonate types of formations. These may be sold as limestone, dolomite or other names. Calcite is another term for some of these rocks that I have not seen in the landscape trade. 
Most of the rocks I use are hard, smooth, rounded rocks of many colors. The local landscape terms include:
Pami Pebble
Red River
Noiyo Cobbles
Lodi

Flagstone, that is fairly flat pieces include
Connecticut Bluestone
Arizona (sandstone, many colors- it is hard, does not slough off in the tank)

Irregular rock
Los Osos (a term I have never seen except in one store, many years ago- REALLY nice black rock)

I avoid rock with noticeable amounts of mica such as
Idaho Quartz
Bouquet Canyon

Each store sells rock from all over the nation, and many stores call the same rock by different names, so the names I use may not be the names you find, but we could easily be talking about the same rock. 

Here is a quick idea:
If a rock comes from a river, it is smooth, rounded because of being tumbled against the other rocks. If it was susceptible to being dissolved by water, wouldn't it have dissolved by now? With all that water pouring over it for so long?


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## mosspearl

What about crystals? I see quartz is okay as long as it isn't tainted with iron, but what about amethyst and other crystalline forms? I have some nice points that might look good in water.


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## bassistjon112

mosspearl said:


> What about crystals? I see quartz is okay as long as it isn't tainted with iron, but what about amethyst and other crystalline forms? I have some nice points that might look good in water.



You can probably use any type of quartz but most quarts that has any color to it will fade/lose color in an aquarium. The light/uv destroys what makes color in quartz thus making it look like clear quartz. I keep all of my crystals in dark areas of my house to preserve the color. Ive seen many beautiful amethyst turn from deep purples to pale lavender colors from sitting near a window. Amethyst, citrine, smokey quartz get their color from iron but i do believe they are all inert. Smokey quartz is black from radiation and I believe it actually gets darker from light. I am no expert but just an amateur rock and mineral collector. Feel free to look this stuff up if you want more details. I would stick with clear quartz/milky quartz though.


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## Hoppy

mosspearl said:


> What about crystals? I see quartz is okay as long as it isn't tainted with iron, but what about amethyst and other crystalline forms? I have some nice points that might look good in water.


Iron isn't a problem. People used to use iron nails in the substrate hoping that would help the plants that need more iron. I would be somewhat concerned about soluble copper compounds, arsenic, etc., but not most metallic inclusions in rocks. Fish live in rivers and lakes that have lots of rocks in them, with various mineral contents.


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## Diana

I think I would differentiate between placing a nail or two deep in the substrate, where the iron might be acted on almost immediately by the humic materials, and naturally chelated before it could do any damage to the livestock, compared to having minerals exposed to the water column in large amounts. 

Some of the rocks in my tanks have rusty spots, suggesting iron. They are just a few spots in a large tank. Perhaps half a dozen spots about the size of a dime, in 125 gallon tank.


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## jrh

I didn't catch all of this, but limestones, dolomites, etc, tend to have lighter colored edges. They look like old D&D dice that have been used a lot... the edges get a little worn and lighter colored.

Iron pyrites (fools gold) is notoriously bad. I'm surprised someone said schists are good.

Tumbled river stone, available everywhere, but often cheapest at a landscaping stone place, where they weigh your car when you drive in, then weigh it again when you drive out, and charge you by weight.


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## Luminescent

What about mica flakes? Good, bad or indifferent. Lot's of natural mica flakes and iron in some of the sand I 'sandwich' between bottom substrate and cap:

That's a magnet:

http://i.imgur.com/MB2EfzEh.jpg

Did a calcium test - nada.


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## jrh

I don't know much about mica. I think it's primarily silica, so should be inert.


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## DaveFish

Well minerals in rocks aren't always affected by water in terms of precipitation. Like Scoria, (vesicular basalt) or (vesicular Andesite) has tons of iron,magnesium,calcium etc... Some Scoria is predominantly Andesitic which means it has 57%-63% Silica. The minerals are trapped in the silicon dioxide and rendered inert.
This is the rock that I sell. It is Scoria with an Andesitic composition. Studies done by BYU.


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## flight50

In about two days I can post my test results from over the course of a month with 8 different rocks. They all passed both the vinegar and the muratic acid test. A couple of shockers as well. I have set up 8 separate containers and monitored them on a weekly basis without doing water changes or anything addition besides just setting them up. There are some changes but they are minimal. With weekly or bi-weekly water changes my future hardscape inductees will fit the bill.


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