- Email: [email protected]
Introduction of James R. Wood for the F.W. Clarke Medal
Award of the V. M. Goldschmidt and F. W. Clarke Medals to interpret his rocks in the Oslo region in that famous 1911 memoir-Gibbs was still inaccessible to him as it was to most chemists of his time-he next moved to crystal chemistry, the newest and most exciting branch relevant to mineralogy. That gave him the insight necessary to understand why certain elements are concentrated in certain minerals, in other words, the laws governing the distribution of the elements. But to check these laws he needed more data and since nobody was going to give him these data, he had no choice but to become a spectroscopist. In the process he also became the chemist of the earth par excellence. Why this stunning success? Part of the answer, I think, lies in the degree to which Goldschmidt was willing to follow the problems wherever they were taking him, even to the extent of becoming a chemist. My wife and I often talk about the causes behind major advances in science. As a historian of mathematics, she has found that among several possibilities, a fusion of two branches of mathematics invariably leads to a new and exciting
833
field of inquiry in which initial progress is rapid. The new field borrows tools and approaches from the parent fields, but it soon goes its own separate way. Isn’t this exactly what Goldschmidt achieved? Trained as a geologist, he acquired enough chemistry to achieve a fusion of the two fields and thus found modern geochemistry, something Van t’Hoff attempted, but did not succeed in. There is a lesson here which I am careful enough not to spell out in detail. Does it mean, perhaps, that it is easier to make a chemist out of a geologist than a geologist out of a chemist? However this may be, let us rejoice now that in Geochemistry we have a lively and exciting field where chemists and geologists can meet, mingle and match their wits, and where through cooperation and friendly competition we can all be winners. In conclusion, I would like to express my deep sense of gratitude to all who made this occasion possible and I want you to remember that it was my students who primarily earned this distinction. Thank you very much.
Introduction of James R. Wood for the F. W. Clarke Medal LAWRENCE HARDIE* Mr. President, Ladies and Gentlemen: The classical approach to understanding low temperature salt-brine equilibria was established just before the turn of the century by J. H. Van t’Hoff, the first Nobel prize winner in chemistry. J. H. Van t’Hoffs objective was to explain the mineral parageneses found in the Permian Stassfurt marine evaporite deposit of Germany. To this end, he and over 30 students and colleagues devoted 12 years to the systematic experimental measurement of salt mineral solubilities, in simple binary systems, ternary systems, and so on, that make up the haplo-seawater system Na-K-Ca-MgCl-S04-H,O. The results were expressed in phase diagrams that were ingenious in their ability to describe the behavior of more than three components in two-dimensional space. Despite this ingenuity there are not enough dimensions on a sheet of paper to cope with an 8 + component systern like seawater, and so no rigorous method of following a complete seawater evaporation path was ever achieved by Van t’Hoff and his followers. Here the problem remains today, almost 70 years after Van t’Hoffs incredible effort. This is where Jim Wood comes in. As an engineering undergraduate at Northwestern he came under the influence of Bob Garrels and Hall Helgeson, both of whom have long been promoting the use of thermodynamic relations to prediet reaction paths in multicomponent systems of all kinds but especially those containing aqueous electro* Department of Geology, University of Wyoming, Laramie, WY 82070, U.S.A.
lytic solutions. It was Bob and Hal who turned Jim on to the thermodynamics of aqueous solutions, and his subsequent entanglement with concentrated brines. It was while trying to survive the supervision of the evaporite-crazed men at Johns Hopkins that Jim came down with Helgeson B-dot fever, from which he happily has never recovered. By combining the Scatchard deviation function with Harned’s Rule, Jim has been able to derive a relation that successfully describes the mean stoichiometric ionic activity coefficients of salts in complex electrolytic solutions of ionic strengths ranging from 2 to over 20. With this model he has been able to predict solubilities of common saline minerals in the system Na-K-Ca-Mg-SO,&-H,O at 25°C. within the experimental error of the values measured directly by the Van t’Hoff method. This work of Jim’s was first presented as his Ph.D. thesis at Johns Hopkins and was subsequently published with additions by the Society last year. Jim’s model is a major breakthrough in our attack on evaporite mineral genesis and brine evolution because it presents us with an opportunity to escape the two-dimensional graphical trap and mass of experimental combinations and permutations that has limited progress in multicomponent brine systems. We can, if we accept the chance, at last reach beyond Van t’Hoff. But that is not all, because the significance of Jim’s brine model does not end with evaporites but can be applied to concentrated electrolytic solutions of all kinds, whether in the laboratory, in natural geological environments or in industrial
x34
Award of the V. M. Goldschmidt and F. W. Clarke Medals
chemical plants. The exciting discoveries of hot, heavy metal-rich brines in the Salton Sea and Red Sea, coupled with the recognition that ore mineral fluid inclusions are very salty, have opened up a whole new awareness of the role of concentrated brines in the origin of many ore deposits. So, too, is it being realized that oceanic spilitic greenstones and amphiholites have formed by interaction of basalts and hot seawater at mid-ocean ridges, and that the resulting CaCl, brines are the sources of the associated sedimentary metalliferous deposits. Jim has already been
able to show that his approach can be applied at elevated temperatures and he has started a program designed to provide us with the coefficients necessary to calculate brine equilibria at hydrothermal temperatures up to about 300°C. We have here then a practical approach to the thermodynamics of concentrated brines that should give us access to geochemically important problems that could not be attacked rigorously before. It is a pleasure to introduce James R. Wood to you.
Acceptance Speech for the F. W. Clarke Medal JAMESR. WOOD* THANK you very much. I would like to express my appreciation and gratitude to the Geochemical Society and in particular the counselors of the Geochemical Society and the members of the Clarke nominating committee. I am deeply honored to be named this year’s recipient of the Clarke Medal, particularly when I recall the previous recipients and their work. It is indeed distinguished company, and I am very pleased to be included in this list. There are a number of people to whom I owe a great deal, both in terms of being named for this award and for their influence and guidance on my career in general. Three people in particular contributed a great deal of time and effort in this cause, Drs. L. A. Hardie and H. P. Eugster of The Johns Hopkins University and Dr. H. C. Helgeson of the University of California at Berkeley. It would be quite difficult for me to say that any single one of these people contributed more than any other: all three of these people have, in their own ways, deeply influenced my development as a student, and have helped shape this study. I think that you can get a better appreciation of what I mean if I give you a brief history of this particular study. It will no doubt surprise many of you who may have read the paper to know that it started out as a field project. There were a number of twists and turns between that start and the final product, but it never the less started out as a field project focussed on Lake Magadii in Kenya, Some of you may be familiar with Lake Magadii. Hans Eugster of course resurrected Lake Magadii from the status of a little known soda lake to a permanent stop on the annual world wide geochemical trek. A pilgrimage 1 can strongly recommend. Even if soda lakes are not your cup of tea, you will still enjoy the scenic beauty of Kenya and the majesty of current geochemical speculation on the origin of this rather simple lake. The scenic beauty was in fact what im+ Department of Earth and Planetary Sciences. The Johns Hopkins University, Baltimore MD 21218. U.S.A.
pressed me the most (unfortunately) and Hans is still looking for someone to explain the origin. You may perhaps by now begin to understand why this paper was not a field project. I think Hans concluded as much after two days in the field with me, and I will spare you those details of those days, but let me say that just because one does not do field work well, that does not mean he doesn’t like it or appreciate the problems connected with it. I enjoy field work, particularly in nice climates. and particularly when others are along to do the heavy work. In retrospect, I think another reason that 1 did not do well in Kenya was because Hans expected me to do all the digging and I preferred to let him do it. This concludes the field stage of this story. The next step was to find me in the lab trying to measure the partial pressure of CO,<,, over sodium carbonate brines. To this day I don’t know why I was measuring P co2 ; but Blaire Jones had just lent us a marvelous P co2 machine and it seemed the thing to do. Unfortunately it was a high PC<,, machine and sodium carbonate is low PcoL. As a result I measured the daily ~uctuations of Pco, in the Baltimore air for three months and concluded that sodium carbonate had a low Pro,, somewhere near atmospheric. Hans concluded I was not a lab man, or as he put it. “Why don’t you go see Laurie?“. Laurie remembered his thesis which concluded measurements of aH20 and suggested I measure the partial pressure of Hz0 over sodium carbonate brines. This may not seem much of an advance over measuring Pco,, but it was, because by that time I was beginning to recall that the thermodynamic properties of brines could be deduced from ai, 1o measurements. This was the beginning of a trail which eventually led to a Ph.D. thesis. a post-doctoral at Berkeley, and still continuing interest in the thermodynamics of brines. I first however had to prove that I was not competent to make the measurements myself. But being an experienced lab man by this time. I managed to do this in a relatively short time.
833
field of inquiry in which initial progress is rapid. The new field borrows tools and approaches from the parent fields, but it soon goes its own separate way. Isn’t this exactly what Goldschmidt achieved? Trained as a geologist, he acquired enough chemistry to achieve a fusion of the two fields and thus found modern geochemistry, something Van t’Hoff attempted, but did not succeed in. There is a lesson here which I am careful enough not to spell out in detail. Does it mean, perhaps, that it is easier to make a chemist out of a geologist than a geologist out of a chemist? However this may be, let us rejoice now that in Geochemistry we have a lively and exciting field where chemists and geologists can meet, mingle and match their wits, and where through cooperation and friendly competition we can all be winners. In conclusion, I would like to express my deep sense of gratitude to all who made this occasion possible and I want you to remember that it was my students who primarily earned this distinction. Thank you very much.
Introduction of James R. Wood for the F. W. Clarke Medal LAWRENCE HARDIE* Mr. President, Ladies and Gentlemen: The classical approach to understanding low temperature salt-brine equilibria was established just before the turn of the century by J. H. Van t’Hoff, the first Nobel prize winner in chemistry. J. H. Van t’Hoffs objective was to explain the mineral parageneses found in the Permian Stassfurt marine evaporite deposit of Germany. To this end, he and over 30 students and colleagues devoted 12 years to the systematic experimental measurement of salt mineral solubilities, in simple binary systems, ternary systems, and so on, that make up the haplo-seawater system Na-K-Ca-MgCl-S04-H,O. The results were expressed in phase diagrams that were ingenious in their ability to describe the behavior of more than three components in two-dimensional space. Despite this ingenuity there are not enough dimensions on a sheet of paper to cope with an 8 + component systern like seawater, and so no rigorous method of following a complete seawater evaporation path was ever achieved by Van t’Hoff and his followers. Here the problem remains today, almost 70 years after Van t’Hoffs incredible effort. This is where Jim Wood comes in. As an engineering undergraduate at Northwestern he came under the influence of Bob Garrels and Hall Helgeson, both of whom have long been promoting the use of thermodynamic relations to prediet reaction paths in multicomponent systems of all kinds but especially those containing aqueous electro* Department of Geology, University of Wyoming, Laramie, WY 82070, U.S.A.
lytic solutions. It was Bob and Hal who turned Jim on to the thermodynamics of aqueous solutions, and his subsequent entanglement with concentrated brines. It was while trying to survive the supervision of the evaporite-crazed men at Johns Hopkins that Jim came down with Helgeson B-dot fever, from which he happily has never recovered. By combining the Scatchard deviation function with Harned’s Rule, Jim has been able to derive a relation that successfully describes the mean stoichiometric ionic activity coefficients of salts in complex electrolytic solutions of ionic strengths ranging from 2 to over 20. With this model he has been able to predict solubilities of common saline minerals in the system Na-K-Ca-Mg-SO,&-H,O at 25°C. within the experimental error of the values measured directly by the Van t’Hoff method. This work of Jim’s was first presented as his Ph.D. thesis at Johns Hopkins and was subsequently published with additions by the Society last year. Jim’s model is a major breakthrough in our attack on evaporite mineral genesis and brine evolution because it presents us with an opportunity to escape the two-dimensional graphical trap and mass of experimental combinations and permutations that has limited progress in multicomponent brine systems. We can, if we accept the chance, at last reach beyond Van t’Hoff. But that is not all, because the significance of Jim’s brine model does not end with evaporites but can be applied to concentrated electrolytic solutions of all kinds, whether in the laboratory, in natural geological environments or in industrial
x34
Award of the V. M. Goldschmidt and F. W. Clarke Medals
chemical plants. The exciting discoveries of hot, heavy metal-rich brines in the Salton Sea and Red Sea, coupled with the recognition that ore mineral fluid inclusions are very salty, have opened up a whole new awareness of the role of concentrated brines in the origin of many ore deposits. So, too, is it being realized that oceanic spilitic greenstones and amphiholites have formed by interaction of basalts and hot seawater at mid-ocean ridges, and that the resulting CaCl, brines are the sources of the associated sedimentary metalliferous deposits. Jim has already been
able to show that his approach can be applied at elevated temperatures and he has started a program designed to provide us with the coefficients necessary to calculate brine equilibria at hydrothermal temperatures up to about 300°C. We have here then a practical approach to the thermodynamics of concentrated brines that should give us access to geochemically important problems that could not be attacked rigorously before. It is a pleasure to introduce James R. Wood to you.
Acceptance Speech for the F. W. Clarke Medal JAMESR. WOOD* THANK you very much. I would like to express my appreciation and gratitude to the Geochemical Society and in particular the counselors of the Geochemical Society and the members of the Clarke nominating committee. I am deeply honored to be named this year’s recipient of the Clarke Medal, particularly when I recall the previous recipients and their work. It is indeed distinguished company, and I am very pleased to be included in this list. There are a number of people to whom I owe a great deal, both in terms of being named for this award and for their influence and guidance on my career in general. Three people in particular contributed a great deal of time and effort in this cause, Drs. L. A. Hardie and H. P. Eugster of The Johns Hopkins University and Dr. H. C. Helgeson of the University of California at Berkeley. It would be quite difficult for me to say that any single one of these people contributed more than any other: all three of these people have, in their own ways, deeply influenced my development as a student, and have helped shape this study. I think that you can get a better appreciation of what I mean if I give you a brief history of this particular study. It will no doubt surprise many of you who may have read the paper to know that it started out as a field project. There were a number of twists and turns between that start and the final product, but it never the less started out as a field project focussed on Lake Magadii in Kenya, Some of you may be familiar with Lake Magadii. Hans Eugster of course resurrected Lake Magadii from the status of a little known soda lake to a permanent stop on the annual world wide geochemical trek. A pilgrimage 1 can strongly recommend. Even if soda lakes are not your cup of tea, you will still enjoy the scenic beauty of Kenya and the majesty of current geochemical speculation on the origin of this rather simple lake. The scenic beauty was in fact what im+ Department of Earth and Planetary Sciences. The Johns Hopkins University, Baltimore MD 21218. U.S.A.
pressed me the most (unfortunately) and Hans is still looking for someone to explain the origin. You may perhaps by now begin to understand why this paper was not a field project. I think Hans concluded as much after two days in the field with me, and I will spare you those details of those days, but let me say that just because one does not do field work well, that does not mean he doesn’t like it or appreciate the problems connected with it. I enjoy field work, particularly in nice climates. and particularly when others are along to do the heavy work. In retrospect, I think another reason that 1 did not do well in Kenya was because Hans expected me to do all the digging and I preferred to let him do it. This concludes the field stage of this story. The next step was to find me in the lab trying to measure the partial pressure of CO,<,, over sodium carbonate brines. To this day I don’t know why I was measuring P co2 ; but Blaire Jones had just lent us a marvelous P co2 machine and it seemed the thing to do. Unfortunately it was a high PC<,, machine and sodium carbonate is low PcoL. As a result I measured the daily ~uctuations of Pco, in the Baltimore air for three months and concluded that sodium carbonate had a low Pro,, somewhere near atmospheric. Hans concluded I was not a lab man, or as he put it. “Why don’t you go see Laurie?“. Laurie remembered his thesis which concluded measurements of aH20 and suggested I measure the partial pressure of Hz0 over sodium carbonate brines. This may not seem much of an advance over measuring Pco,, but it was, because by that time I was beginning to recall that the thermodynamic properties of brines could be deduced from ai, 1o measurements. This was the beginning of a trail which eventually led to a Ph.D. thesis. a post-doctoral at Berkeley, and still continuing interest in the thermodynamics of brines. I first however had to prove that I was not competent to make the measurements myself. But being an experienced lab man by this time. I managed to do this in a relatively short time.