O R G A N O N 24 : 1988 A U T E U R S ET P R O B L È M E S
Endre Dudich (H ungary)
FR O M A L C H E M Y T H R O U G H G E O C H E M IS T R Y TO C O SM O C H E M IST R Y
M otto : “The history o f geochem istry has not been written so far, Even the m aterials for it have not been collected yet.”
(A. E. Fersm an)
IN T R O D U C T IO N
The 100th anniversary o f A. E. Fersm an’s birth furnishes a good opportunity to outline the history o f geochemistry, one o f the sciences studying the E a rth ’s m aterial com position.
Care has been taken to p u t the individual scientists and the achievements discussed into the context o f social, economic and technical developm ent. In fact, on several occasions, w hat seemed to be brilliant ideas rem ained unproductive and only o f historical interest, having appeared before their time and having been technically unw orkable. But in some other cases scientific developm ent was given extraordinary im petus by essential im provem ents o f technical facilities an d /o r changes in the social and economic background.
1. P R E SC IE N T IF IC R O O T S ^ P H IL O S O P H Y A N D A L C H E M Y (F R O M A N T IQ U IT Y T H R O U G H TO T H E E N D O F T H E 16TH C E N T U R Y )
However interesting they m ight be, early Chinese and Indian speculations are disregarded here as having no direct im pact on the developm ent o f geochemistry, a science born in Europe.
It is rem arkable that early atom istic concepts (D em ocritus’s for instance) had no influence either. A ristotle’s philosophy dom inated all m inds in the M editer ranean civilization for alm ost two millennia.
1.1. Anitiquity
A ristotle o f Stagira (384— 322 B. C.) said substance consisted o f two principles: m atter and form , producing four elements (earth, w ater, air and fire) and endowed with four fundam ental properties (warm , cold, dry, wet). C om binations o f these w ould explain all the variety o f n atural bodies.
Accordingly, transform ation o f m aterials (e.g. m etals) into each other was considered possible a priori. This was the concept th a t provided the theoretical basis for the developm ent o f alchemy, directed, first and forem ost to the artificial production o f gold, the noblest o f all m etals, from other less noble ones.
Bolos o f Mendes (Egypt, 2nd century B. C.) is considered to have been the founder o f alchemy. M uch later, about 300 A. D. Zosim os o f Panapolis compiled a treatise consisting o f 28 “ books.”
A t th at time, research went in two distinct directions : hermetic-esoteric philosophy (very hard to decipher and interpret), and pragm atic experimen tation which resulted in a step-by-step invention o f fundam ental laboratory technique.
1.2. M iddle Ages
1.2.1. A rabic Science (s.l.). From the 7th century onwards, the subsequent
Arabic-speaking M oslem empires (expanding from the N ear East as far as Central Asia and Spain, respectively) provided far better possibilities for the developm ent o f science than did Europe o f the “ D ark Ages” after the collapse of the R om an Empire.
Alchemy (the very nam e o f which is also Arabic) was largely elaborated on the .basis o f translations o f Greek and Egyptian works.
In this context, the nam e o f Jabir Ibn H ajjan (8— 9 century), known in medieval Europe as “ G eber,” should be m entioned first.
A bu Reichan A l-Biruni’s (972— 1048) Kitab-il Jaw ahirfi’l Jawahir (B ook o f
Precious Stones in Precious Stones) is a treatise on m ineralogy, m uch m ore
advanced than the classification forw arded by T heophrastos, a disciple of Aristotle.
A bu Ali Ibn-Sina (980— 1037), know n in medieval Europe as Avicenna, m ade im portant critical rem arks on the alchemistic approach, proposing a clear distinction between “essential” and “ non-essential” properties o f m atter.
1.2.2. E uropean Alchemy started with translations from the Arabic. In m ost cases, the authorship o f some often-quoted treatises is som ew hat doubtful. Nevertheless, a few nam es are w orth m entioning.
They include A lbert von Bollstadt (1193— 1280) surnam ed Albertus M agnus ; Roger Bacon (1214— 1294), and R aym undus Lullus (1235— 1315).
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Valentinus assumed a third com ponent called salt. O f course, m ercury, sulphur and salt were not understood in the present-day sense o f these term's.
Individual metals were supposed to be in connection with, and under the influence of, individual celestial bodies (planets). Accordingly, they were given corresponding astronom ic symbols. By a stretch o f im agination these ideas can be recognized as the prescientific roots o f cosmochemistry.
1.3. Renaissance
The early stage o f capitalistic developm ent within the feudal society o f Europe, involving b oth essential progress in technology and new ways o f (relatively) free thinking, led to new approaches.
Bom bast von Hohenheim (1493— 1541), better know n as Paracelsus, left the rather swampy fields o f alchemy to create iatrochem istry (medical chemistry) destined to produce efficient drugs.
G eorg Bauer (1490— 1555), writing under the nam e o f Agricola, sum m ed up in his m onum ental work De re metallica the knowledge won by centuries-old mining experience in Central Europe. He came forw ard with some strikingly m odern ideas, e.g. th at abo u t the ore-generating role o f warm w ater solutions circulating in the “ m ountains,” or rocks.
Nevertheless, alchemy persisted for a long time, till the end o f the 18th century, paving the road tow ards m odern chemistry, but also ham pering its becoming a science.
2. PH IL O SO PH IC A L S P E C U L A T IO N S A N D T H E BIR TH O F G E O L O G Y A N D C H E M IST R Y A S SC IE N C E (17T H — 18TH C E N T U R IE S )
It was at that time th at having dropped the A ristotelian tradition, scholars for the first time began seriously to study the m aterial constitution o f the E arth.
On the philosophical side we are deeply indebted to R. Descartes (1596— 1650) for his two works Le discours sur la méthode (1637) and Principia
philosophiae (1644). Discarding earlier ideas he firmly declared th a t the E arth,
the Sun and other celestial bodies are m ade up o f the same m atter. M oreover, he produced the first figure o f concentric “ shells” o f the E arth, with high-tem perature solar m atter at the centre. Accordingly, he can be regarded as an early forerunner o f plutonism.
“ Geology” in the m odern sense appears, possibly for the first time, in the title o f Geologica norvegica by M. P. Escholt in 1657.
However, it was N. Steensen (Steno) (1638— 1686), with his Prodromus de
solido intra solidum naturaliter contento (Treatise on the Solid Bodies Contained by Other Solid Ones), published in 1669 as the first textbook o f geology, who can be
called “ the first geologist.”
A. K ircher (1601— 1680), a Jesuit with personal experience in cave ex ploration, in the observation o f volcanic eruption and in the telescopic study of
the Sun, published his adm irable Mundus subterraneus ( The Subterranean World) in 1664. This w ork is an amazing intellectual com position o f A ristotelian views, strikingly daring novel ideas and painstakingly described facts observed ■everywhere his correspondence could reach. (The m ethod o f questionnaires had been used, relying upon the extraordinary facilities provided by the global network o f the Jesuit order.) K ircher severely criticized the futile alchemistic approach and suggested ideas abo ut various m ineralizing solutions heated in the E a rth ’s interior by “ prophylacia” (roughly corresponding to m agm a chambers).
G. W. Leibnitz (1646— 1716) in the Abstract (published in 1693) o f his
Protogea arrived at the crucial distinction between fire-born (igneous) and
w ater-born (sedimentary) rocks. W ould his distinction have been taken into consideration by ensuing generations, the long-lasting war between plutonists and neptunists which cost a lot o f energy and trouble might have been avoided.
R. Boyle (1627— 1691), in the England o f the industrial revolution, facilitated the birth o f scientific chemistry by founding m odern atomisms. A t about th at time, R. Boskovic (1711— 1785) in D alm atia conceived a peculiar brand of energetic atom ism s, starting from purely philosophical considerations, which could not be appreciated in pre-Einsteinian times.
In the chronological order, we now arrive at M. V. Lom onosov (1711— 1765), a unique phenom enon in the history o f geological sciences. If his ingenious ideas abo u t the m igration o f elements and—as one would put it now— the geochemical criteria o f ore prospecting, had been appreciated, scientific geochemistry could have been born a century earlier. However, the unfavourable socio-economic conditions prevailing in Russia doom ed him to solitariness as a pioneer o f m odern thought, to be rediscovered and duly appreciated only a century later.
It was in France, at the time o f the intellectual and social m ovem ent o f the Enlightenm ent which relied upon the industrial revolution started in England and led to the bourgeois French Revolution, that m odern chemistry was born, along with some early approaches to geochemistry.
G. F. Ruelle (1703— 1770) undoubtedly contributed enorm ously to the expansion and popularization of chemical knowledge. But it is A. L. Lavoisier (1743— 1794) who is considered to be the F ath er o f Chemistry. (His highly prom ising career was literally cut short by the guillotine.) His work on the chemistry o f w ater and on the physiology o f respiration prepared the way to some geochemical approaches. Leclerque de Buffon (1707— 1788) also touched in his works on several problem s th at can be regarded as “ geochemical” ones.
In England, J. H. Davy (1778— 1829) was already intrigued by differences in the occurrence o f chemical elements in the E a rth ’s crust. At his time, however, this kind o f research, constituting an integral p art o f systematic chemistry, did not develop into a particular discipline. We can speak at best o f beginnings o f geochemistry.
J. Reil (1759— 1813) and A. von H um boldt (1769— 1859) deserve particular attention for having pointed out the im portance o f studying the chemical
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com position o f living organisms. Von H um boldt even emphasized the inter relation o f organism s with the environm ent and their im pact upon natural processes.
In geology (or better perhaps still “ geognosy” ) only A. G. W erner (1749— 1817) elaborated the theory o f neptunism with all its consequences, eclipsing J. H u tto n ’s (1726— 1797) plutonism for a long time. The confrontation between those two theories lasted for several decades, w anting incredible am ounts o f intellectual energy.
In 1798 M. V. Severgin coined the term “ m ineral association,” implying geochemical considerations. His ideas, however, rem ained unknow n outside Russia.
A t the turn o f the 18th and 19th centuries, everything seemed to be ready for geochemistry to emerge. However, as Verbadsky correctly pointed out, that opportunity was missed, and for several reasons. The notions o f atom , element, crystal and m ineral were still rather vague and ill-defined. N o appropriate analytical technique' existed.
M oreover, chemistry and geology developed along different lines. The latter o f the two got involved in the struggle between neptunism and plutonism , and somewhat later, geologists focused upon the elaboration o f stratigraphy (based upon W. Sm ith’s pioneering work). Even later, the conflict o f uniform iiarianism and catastrophism (much m ore sophisticated than is usually thought, as shown in a fascinating way by R. H ooykaas) also contributed to the interest moving away from geochemical problem s, and tow ards evolutionary paleontology.
3. F R O M C H E M IC A L G E O L O G Y TO G E O C H E M IS T R Y (19T H C E N T U R Y )
In spite o f the above-m entioned currents, the chemical approach kept invading geology along three lines.
3.1. Collecting Evidence o f the M aterial Unity o f the Universe
In this context the nam e o f E. F. Chladni (1756— 1827), one o f the outstanding pioneers o f m eteorochem istry, should be m entioned. As far as the m eteorites were concerned, chemical identity and m ineralogical differences were established in com parison with terrestrial materials.
J. Liebig (1803— 1873) developed the chemistry o f living organism s, starting to clear up their role in the natural circulation o f elements (K and P cycles), thus putting into practice the ideas conceived by Reil and A. v. H um boldt, as m entioned before.
3.2. Early Data and Ideas on the Chemistry o f the Geospheres
In this field, I. J. Berzelius (1779— 1848) should be m entioned first, w ithout entering into details.
So far as we know, Chr. Fr. Schonbein (1799— 1869) was the first to use the term “ geochem istry,” in 1838 (according to other sources, already in 1832).
But “ chemical geology” was a m uch m ore widely used term e.g. Lehrbuch der
physikalischen und chemischen Geologie (published 1847— 1854), by C. Bischoff
(1792— 1870).
Geochemical processes connected with volcanism were discussed by Elie de Beaum ont (1798— 1874) in his Emanations volcaniques (1846).
J. F. A. Breithaupt (1791— 1873) wrote a book called Paragenesis der
Mineralien (1849). The concept o f mineral paragenesis, corresponding to
Severgin’s “m ineral association,” involved the recognition o f geochemical processes controlled by geochemical laws. J. H .van’t H off (1852— 1911), who applied physical chemistry to mineral genesis, contributed a lot to the elementary understanding o f these processes.
D uring that stage, the geochemical cycles o f elements were studied in some detail. J. A. B. D um as (1800— 1884), for instance, contributed considerably to the understanding o f the cycles o f oxygen and carbon.
S. A rrhenius (1859— 1927) discussed the geological role o f C 0 2, thus laying foundations for historical geochemistry, dealing with the evolution o f the chemical com position o f the geospheres. By th at time, two indispensable prerequisites for the birth o f m odern geochemistry had been available. Emission spectrography (1860), invented by G. K irchhoff (1824— 1887) and R. Bunsen (1811— 1899) provided a highly efficient analytical tool to would-be geo chemists.
The periodic flaw o f elements elaborated by D. I. Mendeleev (1834— 1907) proved invaluable for the understanding o f the behaviour of chemical elements in function o f their atom ic structure.
3.3. Collecting Experimental Data on Geochemistry
In Russia, V. V. D okuchaev (1846— 1903) created m odern pedology o r soil science, including soil chemistry as an im portant branch. Chemical processes going on in the soil, the site o f intense interaction of the lithosphere, hydrosphere, atm osphere and biosphere, represent a problem o f great im portance in geochemistry even today.
In the USA, F. W. Clarke (1847— 1931) was collecting analytical d ata on the E a rth ’s crust, from 1882 on, with incredible patience and assiduity. His m onum ental work, a veritable “ Old Testam ent” o f geochemistry, entitled The
Data o f Geochemistry, was first published in 1908. To his honour, the average
concentration values o f elements in the E arth’s crust are called “d a rk s .” Curiously enough, Clarke was interested in alchemy in his early years, returning to the topic tow ards the end o f his life.
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Tow ards the end o f the 19th century, m odern atom ic theory was revolutionized by the discovery o f radioactivity (A. H. Becquerel, P. and M. Curie). “ A to m ” and “chemical elem ent” were considered to be identical, b ut atom s were no m ore considered as indivisible and imm utable. The way stood open for some sort of “ m odern alchem y” dealing with the transform ation o f elements. A few years later, the “ solar system” m odel o f the atom , proposed by N. Bohr, opened new vistas to the u nderstanding o f the properties and behaviour o f elements. Positive and negative ions turned out to be just as im po rtant for geochem istry as the neutral atom s themselves.
A t the same time, with the rapid advance o f astrophysics (studying electrom agnetic spectra o f various celestial bodies) it became obvious th at geochemistry was but a special case o f astrochem istry or cosmochemistry.
W ith progress in the understanding o f the geodynam ic processes, it turned out th at in m ost o f the geological processes only the crust is involved. Accordingly, geochemistry should concentrate its efforts prim arily on the investigation o f the com position and processes o f the lithosphere.
4. BOOM O F T H E O R E T IC A L A N D A P P L IE D G E O C H E M IS T R Y (1900— 1945)
This— m aybe the m ost essential— stage in the developm ent o f geochem istry is closely linked up with three outstanding personalities, viz. V. I. Vernadsky, A. E. Fersm an and V. M. Goldschm idt.
If C larke’s Data o f Geochemistry is considered the “ Old T estam ent” o f geochemistry, the oeuvre of this trio can arguably be regarded as its “ New Testam ent.”
T hat is why the year o f the death o f the form er two, 1945, has been chosen as the closing date o f this decisive stage.
4.1. Laying Foundations fo r Theory
The theoretical elaboration o f geochemistry was carried out by V. I. Vernadsky (1863— 1945) in his work o f enorm ous im p a c t: La Geochimie (1924). A disciple o f D okuchaev, he created also a new interdisciplinary science— biogeochemistry, by writing La Biosphere (1929).
A scientist o f equal stature, A. E. Fersm an (1883— 1945), as K. R ankam a and Th. G. Saham a pointed o u t in 1959, “ sought the ultim ate causes o f the distribution o f elements in their atom ic structure and studied their distribution in the Universe, thus incorporating geochemistry with cosm ochem istry.” Fersm an was the first to read an independent university course on geochem istry (M oscow 1912). He attribu ted a fundam ental role to geochem istry in the revolutionary developm ent o f a new world concept, because “ geochem istry is speaking the universal language of atom s.” This would lead to the “ chem icization of
geological thinking,” including the geochemical approach to historical geology, tectonics, and even paleontology (indeed, this is becoming true in our days). A ccording to Fersm an, geochemistry should be capable o f doing a quantitative forecast o f the local distribution and accum ulation o f elements, relying upon universal laws and regional regularities. This direct challenge to apply geo chemistry in mineral exploration was brilliantly m et by both him self and his innum erable disciples. Applied geochemistry got an excellent opportunity to develop rapidly with the newly born Soviet State, which was badly in need of m ineral resources which could be explored over a vast territory o f two continents within a short time and with a m inimum o f expenses.
4.2. Application o f Physical Chemistry and Crystal Chemistry
By this point it is no longer possible to enum erate the names or discuss achievements o f all those who contributed to the rapid developm ent of geochemistry.
W. N ernst, G. N. Lewis and J. H. L. Vogt, should be considered only as examples, and the application of the principle o f the m inim um o f free energy should be mentioned.
V. M. G oldschm idt (1884— 1947), who worked in Oslo and G ottingen, is one o f the giants. He elaborated the laws o f element distribution ( Verteilungsgesetze) based upon ionic radii and ionic potentials, established the geochemical classification or grouping o f elements, studied num erous trace elements, was the first to investigate coal ash, to carry out studies in sedim entary geochemistry, etc.
Silicate equlibria, essential for the understanding o f igneous processes, were
studied at the Geophysical L aboratory o f the Carnegie Institute in W ashington, D C .
4.3. Analytical Data and Interpretation
Side by side with Clarke, H. S. W ashington (1867— 1934) contributed essentially to the d a ta base o f geochemistry.
The invention o f X -ray spectrom etric techniques by A. H adding (1922) provided a new and very useful analytical tool.
Beside the investigation of m ajor and m inor elements, special emphasis was laid upon the study o f the rarest ones. By way o f example, the w ork of H ungarian-born N oble Prize W inner Gy. Hevesy (1885— 1966) on hafnium should be m entioned in this connection.
5. D IF F E R E N T IA T IO N A N D U N IV E R S A L IZ A T IO N (P A R T L Y O V E R L A P P IN G W ITH T H E P R E V IO U S STA G E )
Accelerated progress inevitably resulted in differentiation within the science of geochemistry on the one hand, and in interdisciplinary contacts o f geochemistry with other sciences, on the other.
From A lchem y to C osm ochem istry 269
A t th at time, the m ain research centres o r schools o f geochemistry were M oscow— Leningrad, Oslo— G ottingen, Freiberg, and W ashington. It is easy to recognize th at these had developed on the solid basis o f an old tradition in science and mining o f the countries concerned.
The m ain directions o f research can be indicated as follows (no attem pt is m ade to connect them with names, in lack o f sufficient historical perspective. It w ould be as impossible to enum erate all the prom inent geochemists o f our time as to characterize the trees o f a forest one by one) :
— Geochemical cycles o f individual elements, — Radiogeochem istry,
— Radioactive dating by m eans o f isotope geochemistry, — Paleophysiology,
— Biogeochemistry,
— Regional or landscape geochemistry, — Sedim entary facies geochemistry, — Geochemical petrology,
Geoenergetics,
— Organic geochemistry,
— Geochemical m apping and geochemistry applied to m ineral exploration, — Geochemical foundation o f global tectonics.
O f course, now adays geochemical research is no m ore the privilege o f a few countries. It is taught at the universities all over the world. An international jo u rn al on geochem istry entitled Geochimica et Cosmochimica A cta was started in 1951. This title alone shows th at these two disciplines are considered inseparable.
It should be perm itted the au th o r of this paper to devote a few sentences to the developm ent o f geochemistry in his own country. In H ungary, M. Vendel (1886— 1977) and E. Szadeczky-Kardoss (1903— ) are regarded as pioneers o f m odern geochemistry. The form er contributed essentially to the knowledge o f the laws o f elem ent distribution. E. Szadeczky-Kardoss, beside having produced the first textbook on geochemistry in H ungarian (1955) im proved the geo chemical grouping o f elements and endeavoured to elaborate an all-com prising theory o f the Universe, adopting for it the term “ G eonom y” (1974). O f course, it would be far beyond the scope o f this paper to deal with this topic. It is only to point out th at beside increasing divergence there is also a tendency tow ards unification and universalization in Fersm an’s “ world concept” sense.
6. G E O C H E M IS T R Y B E Y O N D T H E E A R T H
E xtra-terrestrial geochemistry, anticipated by m eteorochem y and astrophysics in the last century, became a handfast reality in the course o f space research, from the 1960s on.
U p to now, it has been restricted to the geochemical research o f the M oon, M ars and Venus, carried out in different ways and at different scales.
6.1. Geochemistry o f the Moon ( “Selenochemistry”)
— A utom atic analysis o f lunar soil (Surveyor missions, etc.),
— A utom atic sam pling o f lunar soil investigated in laboratories on the Earth (both US and Soviet program m es),
— Personal sam pling carried out by astronauts o f the Apollo program m e, including the first professional geologist to step on the M oon (H. Schmitt, m em ber o f the Apollo-17 crew— Dec. 11, 1972).
K /U , Rb-Sr, U T h-Pb and other studies o f the lunar samples changed our ideas ab o u t the origin and developm ent o f the M oon considerably.
6.2. Geochemistry o f M ars ( “Areochem istry”)
M artian geochemistry is only beginning to develop. Earlier analyses of M artian atm osphere accomplished by M ariner spacecrafts were followed by autom ated soil analyses carried o u t by Viking-1 and Viking-2 in 1976. The question of life on M ars, however, has yet to be answered.
6.3. Geochemistry o f Venus ( “Aphroditochemistry”)
Both Soviet (Venera) and Am erican spacecrafts have furnished d ata on the atm osphere o f the “ sister planet“ o f E arth. Starting from the chemical com position and “p— t“ conditions o f the Veneran troposphere, V. L. Barsukov et al. in M oscow used com puter sim ulation program m es to determine the probable mineral com position o f the w eathering crust o f basaltic and rhyolitic rocks, assumed to m ake up the solid surface o f Venus.
International cooperation is fostered by the activity o f CO SPA R (Inter national Commission on Space Research), started in 1958.
A long with the investigation o f the M oon and the terrestrial planets, theoretical generalizations have also been undertaken. Some titles speak for themselves :
A. E. Ringwood (1966) : Chemical Evolution o f the Terrestrial Planets; Y. A. Surkov, G. A. Fedoseev (1974) : Radioactivity o f the Moon, Planets and
M eteorites ;
J. S. Lewis (1974) : Chemistry o f the Solar System ; E. Anders (1980) : Composition o f the Terrestrial Planets.
In space, geochem istry is expanding tow ards the Galilean m oons o f Jupiter and to the giant planets themselves on one side, and M ercury on the other.
It was an event o f great im portance th at a joint Soviet-American Conference was held on the Cosm ochem istry of the M oon and Planets in 1974. If its forces are united, hum an mind is bound by the Universe only. It is only to be hoped th at peaceful scientific cooperation will continue both on E arth and in outer space.
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geochemistry, m ost likely reduced to the use o f prim itive stone tools and suffering o f the effects o f elevated radioactivity, can and should be avoided.
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