Here is the job listing
https://www.usajobs.gov/job/728728400
Michael T. Jarvis
Outreach Coordinator
U.S. Geological Survey
National Minerals Information Center
Reston, VA
Hi all,
After a discussion on MINDAT I looked up some sources of information about the solubility of galena in water at room temperature, and found out that in fact the data that circulate are extremely erratic. Some examples [all recalculated to g/100 ml with the assumption that 100 ml = 100 g (which is an approximation, of course)]:
6.767×10−13 g/100 ml ( https://en.wikipedia.org/wiki/Solubility_table) https://en.wikipedia.org/wiki/Solubility_table)
0.000086 g/100ml ( https://www.fishersci.com/shop/products/lead-ii-sulfide-pb-82-min-thermo-scientific/AAA1026836 https://www.fishersci.com/shop/products/lead-ii-sulfide-pb-82-min-thermo-scientific/AAA1026836)
2.6X10-9 g/100g ( https://en.wikipedia.org/wiki/Lead(II)_sulfide https://en.wikipedia.org/wiki/Lead(II)_sulfide)
8.6X10-5 g/100 ml ( https://en.wikipedia.org/wiki/Lead(II)_sulfide https://en.wikipedia.org/wiki/Lead(II)_sulfide, other reference on the same Wiki-page)
0.01244 g/100 ml ( https://pubchem.ncbi.nlm.nih.gov/compound/Lead_II_-sulfide#section=Solubility) https://pubchem.ncbi.nlm.nih.gov/compound/Lead_II_-sulfide#section=Solubility)
0.01244 g/100ml (Handbook of Chemistry and Physics 49th ed., 1969).
As you can see there are differences up to about 10 orders of magnitude!
Moreover I have the feeling that figures such as 6.767×10−13 g/100 ml (3 digits behind the comma!) or 0.01244 g/100 ml are statistically inacceptable in terms of suggested accuracy). Not many analytical techniques for trace analysis would be able to deliver such an accuracy (not to be confused with repeatability or reproducibility).
Of course many parameters play a role in the determination of the solubility of a substance.
I think the most important in this case is the speed (or better slowness) with which an equilibrium state is reached. That can strongly be influenced by e.g. the specific surface (expressed as surface/mass), the grain size, stirring, possible formation of a passivation layer etc.). I suppose that for galena reaching an equilibrium situation is a matter of weeks, months, if not years? To be honest, I have no idea.
But anyway figures scattering from (about) 7×10−13 g/100 ml to (about) 0.012 g/100 ml are a bridge too far IMHO.
I would appreciate to read your thoughts on the parameters that determine a mineral's solubility in water at room temperature, about reaching the equilibrium state and how the solubility is determined in practice, especially for very poorly soluble minerals.
Thanks for any ideas about this topic.
Kindest regards,
Rik Dillen
Rik Dillen - mailto:rik.dillen@skynet.be rik.dillen@skynet.be
Mineralogische Kring Antwerpen - http://www.minerant.org/ www.minerant.org
Lid worden van de MKA ? http://www.minerant.org/MKA/lidworden.html www.minerant.org/MKA/lidworden.html
MINERANT - 4-5 mei 2024
Antwerp Expo
My geochem classes and field experience is that lead and galina are
very sensitive to pH, oxygen and temperature.
As was discovered in Flint MI, USA lead solubility is greatly
influenced by the properties of water. Properties commonly dismissed
as not important.
Orders of magnitude seem expected with lead in almost all compounds.
The context and lab methods must be specific.
On Sun, Jun 4, 2023 at 8:49 AM rik.dillen--- via MSA-talk
msa-talk@minlists.org wrote:
Hi all,
After a discussion on MINDAT I looked up some sources of information about the solubility of galena in water at room temperature, and found out that in fact the data that circulate are extremely erratic. Some examples [all recalculated to g/100 ml with the assumption that 100 ml = 100 g (which is an approximation, of course)]:
6.767×10−13 g/100 ml (https://en.wikipedia.org/wiki/Solubility_table)
0.000086 g/100ml (https://www.fishersci.com/shop/products/lead-ii-sulfide-pb-82-min-thermo-scientific/AAA1026836)
2.6X10-9 g/100g (https://en.wikipedia.org/wiki/Lead(II)_sulfide)
8.6X10-5 g/100 ml (https://en.wikipedia.org/wiki/Lead(II)_sulfide, other reference on the same Wiki-page)
0.01244 g/100 ml (https://pubchem.ncbi.nlm.nih.gov/compound/Lead_II_-sulfide#section=Solubility)
0.01244 g/100ml (Handbook of Chemistry and Physics 49th ed., 1969).
As you can see there are differences up to about 10 orders of magnitude!
Moreover I have the feeling that figures such as 6.767×10−13 g/100 ml (3 digits behind the comma!) or 0.01244 g/100 ml are statistically inacceptable in terms of suggested accuracy). Not many analytical techniques for trace analysis would be able to deliver such an accuracy (not to be confused with repeatability or reproducibility).
Of course many parameters play a role in the determination of the solubility of a substance.
I think the most important in this case is the speed (or better slowness) with which an equilibrium state is reached. That can strongly be influenced by e.g. the specific surface (expressed as surface/mass), the grain size, stirring, possible formation of a passivation layer etc.). I suppose that for galena reaching an equilibrium situation is a matter of weeks, months, if not years? To be honest, I have no idea.
But anyway figures scattering from (about) 7×10−13 g/100 ml to (about) 0.012 g/100 ml are a bridge too far IMHO.
I would appreciate to read your thoughts on the parameters that determine a mineral's solubility in water at room temperature, about reaching the equilibrium state and how the solubility is determined in practice, especially for very poorly soluble minerals.
Thanks for any ideas about this topic.
Kindest regards,
Rik Dillen
Rik Dillen - rik.dillen@skynet.be
Mineralogische Kring Antwerpen - www.minerant.org
Lid worden van de MKA ? www.minerant.org/MKA/lidworden.html
MINERANT - 4-5 mei 2024
Antwerp Expo
MSA-talk mailing list -- msa-talk@minlists.org
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--
T o m M i t c h e l l (on NiftyEgg[.]com )
Solubility tables should be based on laboratory experiments using very pure
water. Results could be different with our home tap water, which contains
carbonic acid, dissolved oxygen, added chlorine, organic pollution, etc.
On Sun, 4 Jun 2023 at 11:27, Tom Mitchell via MSA-talk <
msa-talk@minlists.org> wrote:
My geochem classes and field experience is that lead and galina are
very sensitive to pH, oxygen and temperature.
As was discovered in Flint MI, USA lead solubility is greatly
influenced by the properties of water. Properties commonly dismissed
as not important.
Orders of magnitude seem expected with lead in almost all compounds.
The context and lab methods must be specific.
On Sun, Jun 4, 2023 at 8:49 AM rik.dillen--- via MSA-talk
msa-talk@minlists.org wrote:
Hi all,
After a discussion on MINDAT I looked up some sources of information
about the solubility of galena in water at room temperature, and found out
that in fact the data that circulate are extremely erratic. Some examples
[all recalculated to g/100 ml with the assumption that 100 ml = 100 g
(which is an approximation, of course)]:
2.6X10-9 g/100g (https://en.wikipedia.org/wiki/Lead(II)_sulfide)
8.6X10-5 g/100 ml (https://en.wikipedia.org/wiki/Lead(II)_sulfide,
other reference on the same Wiki-page)
0.01244 g/100 ml (
0.01244 g/100ml (Handbook of Chemistry and Physics 49th ed., 1969).
As you can see there are differences up to about 10 orders of magnitude!
Moreover I have the feeling that figures such as 6.767×10−13 g/100 ml (3
digits behind the comma!) or 0.01244 g/100 ml are statistically
inacceptable in terms of suggested accuracy). Not many analytical
techniques for trace analysis would be able to deliver such an accuracy
(not to be confused with repeatability or reproducibility).
Of course many parameters play a role in the determination of the
solubility of a substance.
I think the most important in this case is the speed (or better
slowness) with which an equilibrium state is reached. That can strongly be
influenced by e.g. the specific surface (expressed as surface/mass), the
grain size, stirring, possible formation of a passivation layer etc.). I
suppose that for galena reaching an equilibrium situation is a matter of
weeks, months, if not years? To be honest, I have no idea.
But anyway figures scattering from (about) 7×10−13 g/100 ml to (about)
0.012 g/100 ml are a bridge too far IMHO.
I would appreciate to read your thoughts on the parameters that
determine a mineral's solubility in water at room temperature, about
reaching the equilibrium state and how the solubility is determined in
practice, especially for very poorly soluble minerals.
Thanks for any ideas about this topic.
Kindest regards,
Rik Dillen
Rik Dillen - rik.dillen@skynet.be
Mineralogische Kring Antwerpen - www.minerant.org
Lid worden van de MKA ? www.minerant.org/MKA/lidworden.html
MINERANT - 4-5 mei 2024
Antwerp Expo
MSA-talk mailing list -- msa-talk@minlists.org
To unsubscribe send an email to msa-talk-leave@minlists.org
--
T o m M i t c h e l l (on NiftyEgg[.]com )
MSA-talk mailing list -- msa-talk@minlists.org
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