Nederlandse Goudpan Vereniging

"Gold is of the metals the most precious."



Geber





The fall of the Roman Empire in the west during the latter part of the
fifth century was followed by widespread political and economic chaos
that existed in Europe for more than four centuries (the Dark Ages) and
was only slowly terminated by the institution of the feudal system in
the ninth century. This social order passed into decline near the end of
the thirteenth century and was gradually replaced during the next three
centuries by nation-states with monarchial and nobility systems,
coteries of salaried civil servants, and rudimentary parliaments.



The social chaos, incessant warfare, plagues, and general economic
instability during the Early Middle Ages (fifth to the eleventh
centuries) resulted in a marked reduction in mining and placering
operations for gold. With increasing stability in the High and Late
Middle Ages (eleventh to the sixteenth centuries) mining activity
increased, and gold was widely sought and won from many of the
auriferous regions of western and central Europe, the Middle East, and
Middle Asia.





Gold mining and placering in China are very old occupations that were
pursued extensively in medieval times, judging from the records noticed
by Needham (1959). Gold mining in Korea began in the year 1079, but
placers had been worked as early as 1122 B.C. (Mills, 1916); in Japan
gold mining and placering probably began on a small scale about the
beginning of our era, increasing only slowly during the Middle Ages. By
1601 gold mining on Sado Island (west coast of Japan) was well advanced,
as witnessed by a unique scroll some 6 meters long and '/3 of a meter
wide illustrating the technique of mining and refining of gold
(Bromehead, 1942). During the last centuries of the Early Middle Ages,
the Moslem Arabs opened or reopened many of the gold placers and mines
under their suzerainty in Spain, Africa, and the Middle East. Much gold
also reached the Arab caliphates of North Africa over the trans-Sahara
caravan routes through Timbuktu to Fez, Tunis, and Tripoli (Barbary)
from the golden land of Wangara (Bovill, 19 58). Wangara can probably be
equated with the placer belts in the ancient kingdoms of Ghana, Mali,
and Songhai, specifically the Bambuk-Buri, Lobi, and Ashanti goldfields.
The auriferous Hausa states (in northern Nigeria) may also have been
part of Wangara. The secret of the source of the gold in Wangara was
guarded for centuries; the Arabs (Moors) and those who followed in the
Late Middle Ages and in modern times, the Portuguese, French, British,
Dutch, and Spanish, all sent expeditions southward from their lands to
find the fabled golden land of Wangara.






In central Europe the pagan Avars, Czechs, and Saxons mined gold in
Bohemia, Transylvania, and the Carpathians. This particular mining
revival, led mainly by the Saxon and other Germanic peoples, flourished
during the High and Late Middle Ages, particularly in central Germany
(Harz Mountains and Bohemia), France, Italy, and Britain. Events of this
period included the emancipation of the miner from slavery and serfdom
as the Saxon miner became a free agent whose services were in demand
from Britain to Transylvania. In addition, during this period there were
major advances in mining technology, mining geology, and metallurgy,
subjects recorded by Calbus (physician and burgomaster of Freiberg),
Biringuccio (master founder of Siena), Ercker (superintendent of mines
at Annaberg), and Agricola (physician of Joachimsthal and Chemnitz)
during the Renaissance.



During the Middle Ages gold placers were worked in much the same way as
in Roman times, but considerable improvements in the methods of
booming, hydraulicking and sluicing were introduced, especially the use
of "long toms" and rockers. Similarly in bedrock gold mining numerous
innovations and improvements of methods and machines utilized by the
Romans for centuries were introduced, particularly in underground
drainage by employing better Archimedean screws, waterwheels, and force
pumps and in ore crushing and grinding by the introduction of
waterwheels and windmills. Improvements were also made in the miner's
tools and in the techniques of open-cut mining, shaft sinking, drifting,
stoping, timbering, ventilation, lighting, mine surveying and so on.
Hoisting up shafts and inclines was made less onerous by improved
versions of the windlass, often employing horses rather than men.
However, rock and ore were still mainly broken by hand by chipping,
wedging, or grubbing, generally after fire-setting. The techniqu e of
making black powder reached Europe, probably from China, in the Late
Middle Ages, but it is doubtful if the explosive was extensively used
for blasting rock until much later. All these various improvements in
underground mining permitted exploitation of many bedrock gold deposits
below the oxidized zones and in some mines, where drainage adits could
be driven or where improved pumps could be installed, well below the
water table.



Theories of the origin of gold deposits in the Middle Ages



Intellectual activity in much of Europe during the Early Middle Ages
(fifth to the eleventh centuries) and High Middle Ages (eleventh to the
fourteenth centuries) was confined principally to the cloister and
consisted mainly of theological speculations. The only glimmer of
scientific progress during this long dismal period came from the Arabic
schools founded in the ninth and tenth centuries at Baghdad, Damascus,
Alexandria, Cordova, and Seville after the Moslem conquests of the
Middle East, North Africa, and Spain. The greatest and most influential
philosophers, alchemists, and physicians at these schools were Jabir ibn
Hayyan (Geber) (c. 721-815), Abu-Bakr Muhammad ibn Zakariya Ar-Razi
(Rhazes) (c. 865-932), and Abu-Ali al-Husayn ibn Abdullah ibn Sina
(Avicenna) (980-tO37). All held views on certain geological subjects and
on the origin of metals and veins in the earth; those of Geber and
Avicenna merit brief mention.





Geber's writings appeared only in the thirteenth century and have been
variously ascribed to Geber himself and to a number of classical Latin
writers who assembled various Arabic alchemical works. Geber's writings
show a keen interest in chemical methodology and in natural chemistry.
In the latter context, his musings on gold are of interest. The
translation given here is by R. Russell from his Works of Geber,
re-edited by E. Holmyard in 1928 and reprinted in Schwartz and Bishop
(1958, p. 190).



Of Sol, or Gold.



"We have already given you, in a General Chapter, the Sum of the
Intention of Metals; and here we now intend to make a special
Declaration of each one. And first of Gold. We say, Gold is a Metallick
Body, Citrine, ponderous, mute, fulgid, equally digested in the Bowels
of the Earth, and very long washed with Mineral Water; under the Hammer
extensible, fusible, and sustaining the Tryal of the Cupet, and Cement.
According to this Definition, you may conclude, that nothing is true
Gold, unless it hath all the Causes and Differencies of the Definition
of Gold. Yet, whatsoever Metal is radically Citrine, and brings to
Equality, and cleanseth, it makes Gold of every kind of Metals.
Therefore, we consider by the Work of Nature, and discern, that Copper
may be changed into Gold by Artifice. For we see in Copper Mines, a
certain Water which flows out, and carries with it thin Scales of
Copper, which (by a continual and long continued Course) it washeth and
cleanseth. But after such Water ceaseth to flow, we find thes e thin
Scales with the dry Sand, in three years time to be digested with the
Heat of the Sun; and among these Scales the purest Gold is found.
Therefore, We judge, those Scales were cleansed by the benefit of the
Water, but were equally digested by heat of the Sun, in the Dryness of
the Sand, and so brought to Equality. Wherefore, imitating Nature, as
far as can, we likewise alter; yet in this we cannot follow Nature. Also
Gold is of Metals the most precious, and it is the Tincture of Redness;
because it tingeth and transforms every Body. It is calcined and
dissolved without profit, and is a Medicine rejoycing, and conserving
the Body in Youth. It is most easily broken with Mercury, and by the
Odour of Lead. There is not any Body that in act more agrees with it in
Substance than Jupiter and Luna; but in Weight, Deafeness, and
Putrescibility, Saturn, in Colour Venus; in Potency indeed Venus is more
next Luna than Jupiter, and then Saturn: but lastly Mars. And this is
one of the Secrets of Nature. Likewise Spi rits are commixed with it,
and by it fixed, but not without very great Ingenuity, which comes not
to an Artificer of a stiff neck."



Geber's idea of the formation of gold scales and nuggets in situ in
alluvial sands seems to follow from the Greek (Thales, Theophrastus)
postulate that gold originated from water (in Geber's case from
cupriferous waters). Onto that postulate has been grafted the alchemical
idea (also borrowed from the transmutation concepts of the Greeks) that
the sun was capable of transmuting the base metals (e.g., copper) into
gold, as will be discussed in this text. Geber's theory that gold
nuggets are formed in situ in eluvial and alluvial sands, when shorn of
its alchemical fantasies, is not unlike present-day in situ accretion
theories of the origin of gold dust and nuggets in placers.



Geber's description of the properties of gold accord reasonably well
with the known facts. He finds that gold is always closely associated
with Luna (silver); but the association with Jupiter (tin) is not
entirely correct in natural situations. It should be remarked, however,
that gold alloys readily with tin, but natural alloys with this base
metal have not yet been recorded.






Avicenna, the great Persian physician and translator of Aristotle, in
his treatise De congelatione et conglutatione lapidum (de mineralibus)
grouped minerals in a relatively modern way as stones (rocks), sulphur
minerals, metals, and salts. About veins, he had little to say in
detail, but he disagreed with Aristotle and the alchemists of his time
about the role of transmutation of metals in the earth, holding to the
idea that each metal was a specific type of earth (element).






It is interesting at this point to digress briefly and consider the
various alchemical theories on the origin of mineral (gold) deposits.
Alchemy is thought by some historians of science to have developed in
China in the early centuries of our era and to have diff used through
India to the Middle East and Alexandria; others consider a
contemporaneous development in China and Alexandria more probable. The
word al-chemi is evidently of Arabic origin and is said by some to mean
black land (Egypt) in reference to the dark silty soil of the Nile
delta. Another version contends that al-chemi is derived from the Coptic
and means black art, as practised by the early chemists, who dealt
essentially with the reduction of ores, the making of glazes and
glasses, and the concoction of medicinal potions, all mysterious
operations quite beyond the ken of most people of the time. The early
Western alchemists were strongly influenced by Aristotelian views as
well as by those of the astrologers, believing that the centre of t he
earth was a holocaust of fire produced by the focus of the rays of all
the seven known planets upon the earth, which was considered at the time
to lie at the centre of the universe. Thus, Apollo or Sol (the sun)
gave rise to gold, Diana or Luna (the moon) to silver, Mercury to
quicksilver, Venus the metal copper, Jupiter, tin, Saturn, lead, and
Mars, iron. These views were held by many of the great alchemists of the
time, Geber, Rhazes, Paracelsus, and Norton, and by many of the great
scholastic philosophers of the period among whom may be mentioned Roger
Bacon (1214-1292), Vincentius Bellovacensis (I 190-1264), Albertus
Magnus (1200-1280), and his illustrious pupil, Thomas Aquinas
(1225-1274).





Albertus Magnus (Albert of Cologne), Dominican, saint, and patron of
the natural sciences, was one of the foremost philosophers of the middle
Ages and wrote extensively on most aspects of philosophy and on a great
variety of scientific subjects. During his long life Albert traveled
widely, visiting many of the gold placers and mines in central Europe,
as is readily apparent from his many writings. His knowledge of alchemy
(chemistry) was, however, limited. One of Albert's works, De mineralibus
(On minerals), written about 1260, is of particular interest in the
present context. In this work, Albert embraced the Aristotelian view of
nature, basing his science of mineralogy on the "four eternal cause§":
material, efficient, formal, and final. As regards the material cause,
the matter of which the minerals are made, his basis is the four
elements (earth, air, water, and fire). After ranging over the field of
rocks, he turns to the metals such as copper, lead, silver, and gold and
discusses the places where these metals are produced and how they
originated in deposits. His theory is essentially Aristotelian, onto
which have been grafted many of the ideas of the medieval alchemists, as
can be seen from the following passage taken from Wyckoff's (1967, pp.
182-183) translation.






The natural scientist seeks to understand the cause of all these
things; and, as we have said in the science of stones, the place
produces things located in that place because of the properties of
heaven poured into them by the rays of the stars. For as Ptolemy says,
in no place does any of the elements receive so much of the rays of all
the stars as in Earth, because I Earth] is the invisible centre of the
whole heavenly sphere; and the power of the rays is strongest where they
all converge; and therefore Earth is productive of many wonderful
things.



In order to know the cause of all the things that are produced, we must
understand that real metal is not formed except by the natural
sublimation of moisture and Earth, such as has been described above. For
in such a place, where earthy and watery materials are first mixed
together, much that is impure is mixed with the pure, but the impure is
of no use in the formation of metal. And from the hollow places
containing such a mixture the force of the rising fume opens out pores,
large or small, many or few, according to the nature of the
[surrounding] stone or earth; and in these [pores] the rising fume or
vapour spreads out for a long time and is concentrated and reflected;
and since it contains the more subtle part of the mixed material it
hardens in those channels, and is mixed together as vapour in the pores,
and is converted into metal of the same kind as a vapour.



In a later passage, Albert discussed his ideas on the precipitation of
gold. Further, in Wyckoffs translation (P. 233) we read:
"For almost everywhere cold is found, as we have said, in the form of
dust or grains. Moreover, the reason for this is that the material is
subtle, and it is driven out and sublimed. Evidence of this is that
[gold] is found [that looks] like hardened droplets. For in the pores of
the natural vessels the concentrated vapour is repeatedly doubled back
upon it and converted into fluid, which takes [the form of] rounded
drops. And if sometimes they are hollow, elongated, and I look I as if
they were made up of smaller ones, this is because in the neck of the
natural vessel the vapour is not converted or hardened all at once, but a
bit at a time; and thus a second [drop I is added to the first, and
sometimes a third to the other two, just as happens in the formation of
hail."



Albert's concept of the origin of placer gold is of considerable
interest because he was evidently the first to clearly outline an in
situ chemical accretion for gold dust and nuggets in alluvial deposits.
Again from Wyckoff's translation p. 184 we read:



"But gold which is formed in sands, as a kind of grains, larger or
smaller, is formed from a hot and very subtle vapour, concentrated and
digested in the midst of the sandy material, and afterwards hardened
into gold. For a sandy place is very hot and dry; but water getting in
closes the pores so that the vapour can not escape; and thus it is
concentrated upon itself and converted into gold. Therefore, this kind
of gold is better. And there are two reasons for this: one is that the
best way of purifying Sulphur is by repeated washing, and the Sulphur in
watery places is repeatedly washed and purified; and for the same
reason the earthy Quicksilver is often washed and purified and rendered
more subtle. Another reason is the closing of the pores underneath the
water along the banks; and thus the dispersed vapour is well-compressed
and condensed, and is digested nobly into the substance of gold, and
hardens into gold."



Albert's view of the origin of placer gold was challenged by
Biringuccio in his Pirotechnia, written in 1540, and by Agricola in his
De re metallica, published in 1546.






Vincentius Bellovacensis (Vincent de Beauvais), French Dominican,
compiled an immense encyclopedia, the Speculum Majus, of which one part
of three, the Speculum naturale, in 32 books and 3,718 chapters, is a
summary of the natural history known to the western Europeans at the
middle of the thirteenth century. In this great work, Vincent discusses
geology and mineralogy, mostly following the thought of Avicenna and
Albertus Magnus (his contemporary). Vincent believed in the alchemical
sulphur-mercury theory of the constitution of metals, in the
transmutation of metals, and in other alchemical doctrines about the
natural upgrading of base metals with time, to yield silver and
ultimately gold, as the most noble of all metals, shown by the following
statements (see Needham, 1959, p. 639).
"Gold is produced in the earth with the aid of strong solar heat, by a
brilliant mercury mixed with a clear and red sulphur, digested and
ripened for more than a hundred years.... White mercury, fixed by the
virtue of incombustible white sulphur, engenders in mines a matter which
fusion changes to silver... Tin is generated by clear mercury and white
and clear sulphur, digested and ripened for a short time
subterraneously. If the digestion and ripening process is very
prolonged, it becomes silver."



The general theory as enunciated by the later alchemists is best stated
in the words of Aurelio Augurelli (1454-1537), alchemist of Venice, as
freely translated from Vellum aureum et chrysopoeia, published in Venice
in 1515, as follows:
"The origin of the metals is the centre of the earth ... penetrated by
the sun's rays and by other celestial rays which ripen and mature the
assembled vapours that then pass upward and fill fractures in the
crustal rocks. Where the vapours are condensed and cannot move farther
they solidify into those unripe metals that fill veins in the earth's
crust.... Finally with time Nature transforms these metals into gold,
silver, copper, and so on...."



Some of the later alchemists thought that mineral veins were offshoots
of a giant treelike body rooted deep within the earth. The mineral veins
were considered to be the branches of this great tree, and the metals
were supposed to have risen like sap. The treelike body was represented
as growing under the stimulus or influence of some celestial body (in
the case of gold, the sun), and base metals such as lead and copper were
constantly being transmutated into the noble metals. This belief in the
transmutation and growth of metals within the earth's crust was
widespread in Europe in medieval times and had many fanciful
modifications. One of these implied that the minerals and metals were
male and female and produced seeds (the petrific and metalline seeds) by
which they reproduced themselves.



Many interesting accounts of the spontaneous generation and growth of
metals, particularly gold, in the earth's crust were extant in the late
middle Ages and were carried into the literature of the sixteenth to
eighteenth centuries. Several alchemists describe how sprigs and
dendrites of gold grow among the vines of Hungary and Romania. Others
relate how the "golden tree" shed spangles and nuggets of gold like
leaves, and seeds, and how these particles of gold gathered in the soils
and alluvium - an interesting origin indeed for eluvial and alluvial
gold placers. Adams (1938) mentions a thesis in the University of Halle
entitled De auro vegetabilipannoniae, written by a certain Huber in
1733, which presents a comprehensive study of the literature on the
vegetable growth of gold. The translation of a part of this thesis as
given by Adams (p. 295) is as follows:





And just as in these places there are growing plants, members of the
Vegetable Kingdom, so not infrequently, by a natural spectacle which is
altogether wonderful and delightful, it comes to pass that gold, as if
joined with these vegetable growths by a bond of consanguinity, laying
aside, as it were, its own metallic character, grows after the fashion
of plants out of the same lap of Mother Earth. Between the gold and the
vine, indeed, these observers relate that there exists so close an
intercourse: that the gold not only embraces the vine externally under
the form of threads after the fashion of a climbing plant: but that even
the vine sometimes puts forth little shoots and tendrils of pure gold,
sometimes little berries of the same metal between its leaves. Gold is
found intimately associated not only with the vine but with other
vegetable growths: occurring either twisted up in various manners with
their roots, or else growing near them in the form of little strings or
threads. And this species of gold s pringing after the manner of
vegetable growths, or in the midst of them, we designate by the name of
Vegetable Gold.



Huber apparently espoused the opinion then current that the gold grew
like a plant, in some cases in dendritic or treelike forms, about the
roots of vines. Gold associated with the roots of plants, especially
those that are decaying, is not uncommon and is obviously the result of
the reduction of auriferous soil solutions by decaying vegetation. In
some places it is apparent that distorted nuggets of gold grew in this
manner. Furthermore, it is interesting to note that the observation by
the medievalists of enrichments of gold below trees has been amply
confirmed by modern analysis of humus and mull developed in the A
horizon of soils beneath heavy forest cover. A number of alchemists and
early mineralogists believed that each metal began as a soft plastic
material that they called gur or bur. This material oozed out of
fissures and was probably ordinary limonite, fault gouge, and other
unctuous substances like kaolinite and precipitated carbonates. There
were still others who connected the veins and metals with the breathing
of the earth, which was thought to function and exhale like a giant
animal. This theory was current in the seventeenth century and was
adopted by Kepler (1571-1630), the great German astronomer. The idea of
the growth and transmutation of metals, however, held the general stage
and greatly influenced the views of the old mining geologists. On
finding bismuth, cobalt, and zinc in the veins instead of gold and
silver, they said "We have come too soon," implying that the baser
metals had not yet had sufficient time to be transmuted (ripened) into
the noble metals. These and a host of other fantastic ideas were held
from early medieval times until the birth of modern chemistry in the
latter part of the seventeenth century. Even Robert Boyle, the "father
of modern chemistry," in his Sceptical Chymist (published in 1661) could
not quite bring himself to discard the views of the ancients about the
magical growth and spontaneous generation of minerals in the earth.
These Western ideas about the or igin of mineral (gold) deposits had a
parallel development in the Indian and Chinese civilizations that merits
brief mention.



The early Indian (Hindu) and Chinese philosophers perceived matter in
terms of four material elements, earth, water, air, and fire (light), in
much the same way as those in Asia Minor and the Mediterranean. Alchemy
was also practiced at an early stage in both the Indian and Chinese
civilizations, and as mentioned previously may actually have originated
in China before our era. Like Western alchemists, the Chinese also
believed in the transmutation of the elements in the earth.



According to Allehin (1962) bedrock gold mining in India declined in
southern India in the early part of the third century A.D., evidently
due to the breakup of slavery as a social institution. Another factor,
particularly in the Hutti and Kolar fields, appears to have been that
the rich auriferous oxidized zones were worked out and water problems
were encountered with which the miners could not cope. Placer mining,
however, continued over much of India during medieval times but only on a
small and local scale. The decline in gold mining is reflected in the
literature of the Gupta period (A.D. 320-500), the period of some seven
centuries marked by an endless succession of internal wars and foreign
invasions, and by the Delhi Muslim Sultanate, founded in A.D. 1206 and
ended in 1526 with the establishment of the Mogul Dynasty. Nowhere, as
far as I can find, does the literature of these periods deal with gold
and its deposits in more than a cursory manner. Professor J. Needham
(1959, p. 650) has given us an adm irable account of the geological
sciences in ancient China in his Science and Civilization in China. In
this work there is a passage dealing with the formation of mineral
deposits written by Chang Szu-Hsiao, who died in A.D. + 1332.



"In the subterranean regions there are alternate layers of earth and
rock and flowing spring waters. These strata rest upon thousands of
vapours (chi), which are (distributed in) tens of thousands of branches,
veins and thread (-like openings). (There are substances there) both
soft and firm, ever flowing back and forth, and undergoing
transformations. (The veins are) slanting and delicate, like axles
interlocking and communicating. (It is like a) machine (chi) rotating in
the depths, (and the circulation takes place as if the veins had)
intimate mutual connections (and as if) there were piston bellows (at
work). The mysterious network (hsiian kang) spreads out and joins
together every part of the roots of the earth. The (innermost parts of
the earth are) neither metal nor stone nor earth nor water (as we know
them). Thousands and ten thousands of horizontal and vertical veins like
warp and weft weave together in mutual embrace. Millions of miles of
earth are as if hanging and floating on a sea boundlessly v ast. Taking
all (including land and sea) as earth, the secret and mystery is that
the roots communicate with each other. The natures, veins, colours,
tastes and sounds, both of the earth, the waters, and the stones, differ
from place to place. So also the animals, birds, herbs, trees and all
natural products, have different shapes and natures in different places.





Now if the chi of the earth (ti chi) can get through (the veins), then
the water and the earth (above) will be fragrant and flourishing ... and
all men and things will be pure and wise.... But if the chi of the
earth is stopped up (sai), then the water and earth and natural products
(above) will be bitter, cold and withered ... and all men and things
will be evil and foolish.... The body of the earth is like that of a
human being. In men there is much heat in and under the watery abdominal
organs (shui tsang); if this were not so, they could not digest their
food nor do their work. So also the earth below the aqueous region is
extremely hot; if this were not so, it could not 'shrink' all the waters
(so chu shui) (i.e. evaporate them and leave mineral deposits), and it
could not drive off all the (aqueous) Yin chi (hsiao chu Yin chi).
Ordinary people, not being able to see the veins and vessels, which are
disposed in order within the body of man, think that it is no more than a
lump of solid flesh. Likewise, not being able to see the veins and
vessels, which are disposed in order under the ground, they think that
the earth is just a (homogeneous) mass. They do not realise that heaven,
earth, human beings, and natural things, all have their dispositions
and organizations (wen li). Even a thread of smoke, a broken bit of ice,
a tumbledown wall or an old tile, all have their dispositions and
organizations. How can anyone say that the earth does not have its
dispositions and organizations?"



In this passage we have an exposition, albeit rather convoluted, of the
precipitation of mineral matter from aqueous solutions and an
intimation of the theory of lateral and metamorphic secretion. The
comparison of the manifestations of the earth with the human body is
interesting in that similar analogies were made by a number of medieval
European alchemists.



Gold is mentioned in many of the works of the early Chinese
philosophers. Needham (1959, p. 674) quotes two that are of interest.
The first is from the Kuan Tzu book.



"Huang Ti said, 'I should like to know about these things.' Po Kao
answered, 'Where there is cinnabar above, yellow gold will be found
below. Where there is magnetite above, copper and gold will be found
below. Where there is ling shih above, lead, tin, and red copper will be
found below. Where there is haematite (che) above, iron will be found
below. Thus it can be seen that the mountains are full of riches.'"



and the second from the Pen Tshao Shih I of A.D. +725.



"Generally one sees those who search for gold dig down into the earth
for several feet until they come to a stone called ffln tzu shih
('tangle-stone') (which accompanies the gold). This is always in black
lumps, as if charred, and underneath it is the gold-bearing ore, also in
lumps, some as large as one's finger, others as small as beans, and
coloured a mulberry yellow. When first dug out it is friable."



Geologists will recognize that the statements in both quotations
represent probably the first attempts to describe zoning in gold
deposits. The "tangle stone" is evidently limonite and/or wad from the
description. Quite frequently, gold is greatly enriched where black
manganese or wad and limonite are developed in the oxidized zones of
gold deposits. The gold referred to as a mulberry yellow colour is
evidently secondary (or mustard) gold, which is often friable or
pulverulent. Needham (1959, p. 675) also quotes some surprising
information about early Chinese knowledge concerning the association of
plants and mineral deposits and about the use of geobotanical and
biogeochemical prospecting in China as far back as A.D. 800. The
statement about the plant indicators of silver and gold in the Yu- Yang
Tsa Tsu is of interest.



When in the mountains there is the tshung plant (the ciboule onion),
then below silver will be found. When in the mountains there is the
hsiai plant (a kind of shallot), then below gold will be found. When in
the mountains there is the chiang plant (ginger), then below copper and
tin will be found. If the mountain has precious jade, the branches of
the trees all around will be drooping.



Professor Needham goes on to discuss how the early Chinese noted the
deleterious (chlorotic) effects produced in plants by excesses of
elements such as copper and lead; finally he remarks on how the early
Chinese discovered that certain plants accumulate metals, for example,
gold by the rape-turnip (Brassica rapa-depressa), and so on. Boyle has
attempted to explain these phenomena based on the sulphur content
(derived from auriferous sulphides) of the various plant species that
indicate or accumulate gold, but later research has shown that this
answer is not complete. The historians tell us that the Late Middle Ages
(fourteenth and fifteenth centuries) in Europe were marked by great
confusion and chaos fomented by economic depression, wars (the Hundred
Years War), schisms in the Roman Church, rebellions and revolutions, and
widespread plagues (the Black Death). Science progressed little, and
few writings of this desperate period are of much interest to
geologists. Nevertheless, people had to eat, and agricul ture, mining,
and industry continued, often in a desultory manner, as armies,
disgruntled barons, and rebellious mobs fought out their quarrels across
many European lands. In art, literature, and science there was much
threshing of old grain from which few kernels of new approaches and
knowledge emerged. In science, challenges to the Aristotelian
(deductive, speculative) concept of nature as promulgated by Thomas
Aquinas and others continued, especially initiated by Oxfordians Robert
Grosseteste (I 175-1253) and his pupil Roger Bacon (1214-1292), who
sought to lay bare the secrets of nature by the methods of experimental
study, thereby introducing the modus operandi of modern science.



In technology, advances in metallurgy, especially in alloys, led
directly to the invention of movable type and printing in the middle of
the fifteenth century. This invention was to have far-reaching effects
in all human endeavours, especially science and technology. The Greek
and Latin classics became readily available, and numerous technical
manuals made their appearance in the latter part of the fifteenth
century and during the sixteenth century, especially in the fields of
mineral deposits, mining, and metallurgy. The invention of cannon, which
reduced the castles (fiefdoms) of the nobles and strengthened the hands
of the monarchs, led to greater emphasis on metallurgy and a great
demand for metals such as copper, tin, and zinc. To meet these
requirements the miners of central Germany (Bohemia), the principal
source of metals in Europe at the time, invented piston pumps for
dewatering their mines, thus allowing deeper and more sophisticated
mining methods. The old records also show that considerable pros pecting
proceeded during late medieval times particularly for gold and silver,
metals increasingly required for specie as payment for the spices,
silks, and other goods avidly sought from India and the Orient. We read
that bedrock mines were developed in many parts of Bohemia, at Kremnitz
(Kremnica) and Schemnitz (Banska Stiavnica), in the Vosges, Auvergne,
and Pyrenees in France, and elsewhere in Europe. Many of these mines
produced principally silver, but much gold was also won from their ores.
Gold placers were worked along the Rhine, Rhone, Garonne, Po, and other
European rivers. Rickard (1932) for instance tells us that Aeneas
Sylvius, writing in 1458, boasted of the mineral wealth of Germany,
saying: "Gold dust sparkles in the waters o the Rhine; there are rivers
in Bohemia in which the Taborites find lumps of gold the size of peas."
Finally, improvements in navigation, in ocean-going ships, and in the
knowledge of geography were to lead to the tracing of routes around
Africa to India and the Far East, the rediscovery of the Americas, and
the circumnavigation of the globe in the late fifteenth century and
early sixteenth century, events that were to transform the
civilizations.



References and selected bibliography

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