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Solubility of minerals

Posted by Reiner Mielke  
Bart Cannon June 19, 2012 01:28AM

That is a good point. Barite crystals are everywhere, but quartz crystals are even more common.

One could place either in a glass of water and neither would dissolve in a 100 million years.

Hydrothermal conditions can do wonders for mineral precipitation.

But what about Norman, Oklahoma and its barite roses ?

I think those things are still forming in soil.

Henry Barwood June 19, 2012 01:46AM
Sorry to jump into this topic, but many of the barite, celestite, etc. minerals that are shale or nodule hosted form from expelled solutions as the shale consolidates. The same is true of lime muds. These have nothing to do with weathering at all.

For years I had people claim that the Virginia turquoise crystals were forming rapidly on the dumps. I searched for years for anyone who could provide me with an example of the oft cited "turquoise crystals growing in a root" and drew a blank. It has been a long time since I calculated a solubility constant, but most minerals are a lot more complex than just "water soluble".

Henry Barwood
Troy University
Troy, Alabama USA
Tom Tucker June 19, 2012 02:55AM
Yes Bumpi, but even the water displaced during sediment consolidation can't account for precipitating all that barite (baryte) can it ? I don't have my Handbook of Chemistry handy, but I think it'll take a bunch of water to precipitate even a single little barite crystal. Are complex ions involved ?
Henry Barwood June 19, 2012 03:07AM
Hi Tom,

There is a lot of water in mud. As it is compressed, not only the water, but cations and anions that were absorbed on the clays, are expelled. If there are pathways present, the fluids migrate into new areas. If they reach a point where the eH and/or pH changes, minerals will precipitate. Imagine the water contained in a 20 foot thick layer of mud that compresses to a foot thick layer of shale and you will have some idea of the scale of this process. Remember that things like barite are not moving as Barium Sulfate, but as soluble Barium complexes and Sulfate anions. When they reach a favoralbe site, you get barite.

Deeper burial introduces heat and additiional release of ions. The hydrothermal (or very low-grade metamorphic zone) is one of our most important ore-formers.

Henry Barwood
Troy University
Troy, Alabama USA
Bart Cannon June 19, 2012 05:30AM
Haven't we all wondered how long it takes a crystal to grow in the natural environments ?

Other than evaporate minerals, as far I know. NOBODY knows !

Famed Arizona mineral dealer Dick Jones knew exactly how long it took a bloedite crystal to reach a saleable size in one of his hatchery holes out in the Salton Sea, I think it was. He would dig a pit and return to collect his progeny when they reached maturity..

I am probably wrong about both the dealer's name and his hatchery's name.

Rock Currier June 19, 2012 08:05AM
The locality for the Blödite is Soda Lake, Carrizo Plain, San Luis Obispo Co., California, USA. I went collecting with Dick Jones and Gary Novak there for Blödite and nether of them said anything about hatchery holes. Most of the ones we found were less than two inches in size. We each came away with several hundred crystals for our effort. The really big ones were found by Art Eadie, a petroleum geologist who collected rare species and lived in Taft, California, a stones throw from the locality. He even had a claim on parts of the lake. He went to hi maker without telling anyone about where and how he found the giant Blödite crystals on the lake.

Rock Currier
Crystals not pistols.
Bart Cannon June 19, 2012 12:58PM

I sure wish I had hung onto one of Art Eadie's business cards though I certainly could not have shown it to my mother.

I forgot about the Dick Jones / Gary Novack connection. Many curious stories there including puzzling smoky quartz..

Maybe at a later date, but I'm pretty sure that there was some kind of hole digging going on and harvesting from them.

I can only barely remember what Dick Jones looked like so maybe I'm remembering something else.

I think he used to hire a plane to follow his competitors into their locations, or maybe it was the other way around.

Reiner Mielke June 19, 2012 03:50PM
Hello Bart,

Assuming your sample of barite and silver has enough silver in it to stay in one piece, you should be able to remove the barite by heating and quenching the sample in cold water, barite will crumble silver will not.

Edited 1 time(s). Last edit at 06/19/2012 03:51PM by Reiner Mielke.
Bart Cannon June 19, 2012 08:24PM

Thanks !

Heating and quenching was my method of first choice. It was standard procedure for removing basalt from Keeweenaw coppers.

It didn't work on the silver and barite. Maybe I should get the specimens hotter.

Jeff Weissman June 19, 2012 11:52PM

When removing catalyst washcoat from honeycomb monoliths, we first dip in liquid nitrogen, followed by heating in a flame. Takes a few cycles, but eventually the washcoat flakes off - you may want to get your barite much colder and see if that works for you.
Bart Cannon June 20, 2012 03:29AM

It just so happens that I filled my LN2 dewar today. Of course I use it for my EDS system, but people show up to have their warts removed. A very notable Mindater has done so, but demanded a triple treatment. It worked out.

Maybe I'll dip a silver/barite in.

My dewar weighs 51 pounds when full and it strains me to get it into my car.

There was a 120 pound kid waiting to have his dewar filled. It weighs 100 pounds when full, yet he hefted into his Volvo without difficulty.

His name is Daniel Troberg of Robison Engineering. He uses LN2 to cool down computer processors to put them into overdrive without burning out the microscopic transistors. He told me he holds second place on Earth for processor speed. He is about 23 but already bored with his career.

I think I'll hire him to re-design my TV processor scanning system in my electron microprobe.

Rock Currier June 20, 2012 09:20AM
I think somewhere I have one of Art's business cards.If and when I find it Ill save it for you. I don't think they collected Blödite more than once of twice because like the thenardite, there was little market for the stuff and it was a lot of work for the little return you could get out of the stuff. I had a 4 inch flat pilled full of Blödite crystals for years and was not able to sell them. I don't know what happened to them May have sold them to the mineral of the month club or something. Sam Nasser of Arizona told of visiting Dick Jones at his home in Casa Grande one time and finding him in his garage with an old dental x-ray unit irradiating Japan law twins from New Mexico to turn them smoky. I don't know if that story was true or not. I'm not convinced that a dental x-ray unit would turn quartz smoky.

Rock Currier
Crystals not pistols.
Emanuele Costa June 20, 2012 03:22PM
Hi to All,

after reading the very interesting post I would like to return to the original question of Reiner and submit my very poor experience.... There are no practical and easy way to determine the real solubility of a mineral, except for that ones that are READILY and VERY soluble like halite.

I normally work with poor-soluble minerals, like calcite and gypsum, (but they are not insoluble! calcite dissolve in destilled water for about 0.02 g/l, and gypsum about 2 g/l depending on temperature and other various factors) studying the precipitations of these substances, changing the environmental conditions. If one want to really knows if a small amount of a mineral dissolve in water, this one should use analitical techniques like atomic absorption flame fotometry or titration or even more complicated ones. No way to determine, in a small fragment of a mineral, in few hours, if something can dissolve. Surely something dissolve, but if you dont see strong variations on the surface of the crystals, like specular surface becomed hazy or etch pits or rounding of the edges, you cannot state that the minetral is really insoluble.

So, for a poor rockhound with a poor homemade laboratory is difficult to affirm that the substance he found is really insoluble. One of the simplest thing I can imagine (but you need at least 0.1 g of mineral or so) is to crush the mineral in fine powder - some like sugar - put it in a little glass vial with 10 cc of destilled water, leave it - better under agitation - for some 24/48 hour AVOIDING CONTACT WITH AIR (rubber stop), leave it standing calm and quiet until the liquid portion on top is very clear (not cloudy, no suspended material) and collect that clear portion with a glass pipette (some 1 ml).

You will after put this 1ml test drop on a very clean glass surface, and evaporate it gently avoiding contact with dust. If the drop leave evaporating a halo of solid material , this could be a suggestion that some of your mineral was dissolved. MAKE ALWAYS A REFERENCE TEST (NO MINERAL) with your destilled water: some of these are only deionized, and may be they have inside a lot of silica (sio2 in colloidal form).


If you do this with some minerals, you could have a reaction with water and air oxygen - I.E. pyrite react a little with oxygen, and could form a little of iron sulphate, and this is very soluble - this is the reason why one should use rubber stop.

and if you have the formation of some colloidal suspension, you have material in water but this is not a real solution.

and you have to be sure that the sample you used for the test is very pure,

So the question is not so simply.

I tried to do my best with english, but please be indulgent with an Italian rockhound.

Best Regards to All

Emanuele Costa
Torino (Italy)
Jeff Weissman June 20, 2012 05:28PM
Bart, I can sympathize with your hauling of LN2 dewars - I can remember "riding" them down the sloping hallways of Carnegie Mellon, in Pittsburgh, hoping not to crash into the wall at the end of the corridor - once they get going, even on a moderate slope, hard to stop all of that momentum, but I was much younger and less careful back then, and needed the occasional cheap thrill. But we are getting off topic.
Łukasz Kruszewski July 12, 2012 09:37PM

In general, there is not such thing as INSOLUBLE material. The time when it passes into solution in form of ions depends on its chemistry. HgS and PdS are, e.g., two such cases, when the substance needs a PLENTY of time to pass into solution. But, believe me, it will pass. A man in our Institute did a research: he put cinnabar into pure water and analyzed the water for Hg after few years. The result was positive.


Luke K.
Reiner Mielke July 13, 2012 12:47AM
Thank you for your comments on solubility. I was not concerned with the actual solubility but relative solubility, that is any solubility that can be observed in a relatively short time ( < 24hrs). The reason for this is that such information can be very useful in helping identify minerals cheaply and quickly but this requires a database that is practical and accurate which we currently do not have. The main problem is that confirmed samples need to be used to establish such a database and those can be difficult to come by. For example, the published literature on Bobdownsite says that it is insoluble in acid. I asked the authors of the paper about this a year ago and got no response. Also no one seems to have a confirmed sample, although many dealers say they have Bobdownsite for sale (which would have been called Whitlockite a few years ago) but none of it is confirmed. I have such a "Bobdownsite" sample in my possession and when I tested it, it was readily soluble in HCl.
I have encountered similiar problems with other minerals.
Owen Lewis (2) July 13, 2012 12:22PM
Jolyon Ralph Wrote:
> This got me thinking.
> Is Ice soluble in water? Or does it just melt?

It melts. The presence or absence of extraneous liquid H2O neither helps nor hinders the phase change. The necessary additive to effect the phase change is energy (applied at atmospheric pressure usually in the form of heat). The quantity of energy required to cause the phase change of a quantity of a pure solid material to its liquid state without any rise in temperature is a property of each material and is known as the latent heat of fusion. In the case of pure H2O at atmospheric pressure, the energy required to change one kilogram of ice to water with no rise in temperature is 334 kiloJoules.

The solid/liquid phase change is bi-directional. I.e. it takes the removal of 334kJ from 1kg of water to change it to ice. Energy transfer also governs transition between the liquid and gaseous state but for the same material the latent heats of fusion and vaporisation are different. In the case of H2O, the latent heat of vaporisation is 2260 kJ/kg.

Edited 1 time(s). Last edit at 07/14/2012 12:33AM by Owen Lewis (2).
Elshami T April 16, 2013 09:37PM
There is no such thing as the solubility of minerals in water. The great lord Kelvin himselt made the same mistake shortly before his death
when he tried to calcaulate the age of our earth using the amount of dissolved matter in sea water and the rate of solubility The result was about
20 000 years compared to about 4.5 billion years . Mineral forming elements do not go into solution in the the same proportion in which
they occur in the solid mineral. Thus, minerals decompose in water rather than dissolve in it.
Rock Currier April 16, 2013 11:10PM
I never thought of it that way, but of course he is correct. I feel however that this argument will not change the wording that people use from Soluability to anything else.

Rock Currier
Crystals not pistols.
Doug Daniels April 17, 2013 02:00AM
It wasn't Lord Kelvin that did this calculation- he used heat flow and cooling of a molten Earth. I think Joly did the salt-into-the-ocean calculation, but didn't take into account the fact that dissolved minerals (yes-dissolved) can also precipitate back out of solution. The cycle can repeat many times, messing up your calculation.
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