United States. Dept. of Commerce and Labor United States. Bureau of Foreign Commerce.

Consular reports, Issues 224-227 online

. (page 64 of 92)
Online LibraryUnited States. Dept. of Commerce and Labor United States. Bureau of Foreign CommerceConsular reports, Issues 224-227 → online text (page 64 of 92)
Font size
QR-code for this ebook


coaches, and sleeping cars were made in the United States. This
railway does a large business, both passenger and freight. There
are many large towns along the line, and the territory through
which it passes is fertile and populous, and has great resources yet
undeveloped.

DIAMONDS.

Diamantina lies 680 miles from Rio de Janeiro, and has from
6,000 to 8,000 inhabitants. As its name indicates, it is the capital and
center of the principal diamond district of Brazil. It was founded
in the last years of the seventeenth century as a gold-mining camp;
in 1729, diamonds were discovered. These were at once declared
State property by the King of Portugal, and for a hundred years
mining of diamonds in Brazil was a Government monopoly. In
1832, the Brazilian Government legalized private mining. Before
that time, the Government superintendents and contractors had
worked the mines with gangs of imported slaves, and in a most short-
sighted manner. The district shows the indelible results of such a
regime. To this day, there is an enormous preponderance of negro
blood, and immense deposits of diamond-bearing gravel are irre-
coverably lost, because they have been covered with detritus of other
workings.

There are six important diamond districts in Brazil.

(i) Diamantina.



Digitized by



Google



DIAMOND AND GOLD MINING IN MINAS GERAES. 537

(2) Grao Mogul, also in the State of Minas and 150 miles from
Diamantina.

(3) The Chapada Diamantina, in the State of Bahia, which pro-
duces quantities of amorphous and black diamonds, used for making
drills.

(4) Bagagem, 200 miles south and west of Diamantina. This
was worked as early as the middle of the last century and produced
the celebrated Estrella do Sulof, 254 carats; but the general results
were unsatisfactory as compared with those of Diamantina and Grao
Mogul. The district has been but imperfectly explored.

(5) Goyaz, in the State of the same name, near the River Ara-
guaya, a navigable tributary of the Amazon.

(6) Matto Grosso, 100 miles north of Cuyaba, the capital of the
State, and 1,000 miles west of Rio de Janeiro.

The first three districts lie on or near the crest of the great
mountain chain of the Serra de Espinhaco, or its continuation under
different names, which forms the watershed between the SSo Fran-
cisco, flowing north more than 1,000 miles before it turns toward the
Atlantic, and those rivers which flow directly into the ocean between
Rio de Janeiro and Bahia. It is the opinion of experts that these
three diamond districts are all parts of a great diamondiferous re-
gion extending in a narrow belt along the crest of the serra and down
its slopes for more than 500 miles. It is therefore probable that
further discoveries may be expected in the intervals between the
districts already productive. That in th6 vicinity of Diamantina
the country rock, from which the diamonds have, been washed by
erosion into the beds of the streams, exists only in the central serra
and not in the side mountain chains, is proved by the fact that dia-
monds have been found in all, or nearly all, of the streams which flow
into the left side of the Jequitinhonha, and none in those flowing into
the right bank. The Jequitinhonha is the most famous of all the
diamond rivers, and the most extensive and successful operations in
Brazilian diamond mining have been conducted in it and its upper
tributaries.

Four distinct kinds of diamond mining are practiced in the Dia-
mantina district. The first is the most ancient and simplest. Near
the top of the serra the small streams are very steep in their descent
and have precipitous rocky sides. Their beds are filled with bowl-
ders, and in the interstices the diamond-bearing gravel is found.
This gravel is called the **formacao," and is easily recognized by an
experienced miner, for the reason that it contains certain minerals
whose presence indicates the diamond. The diamond is a heavy min-
eral, its specific gravity being about ;^.6, much greater than that of
ordinary rock. When the mother deposits in the high serra were



Digitized by



Google



53^ DIAMOND AND GOLD MINING IN MINAS GERAES.

eroded and washed into the streams, the diamonds and other heavy
minerals were separated from the bulk of the detritus by the action
of the water. The heavy gravel thus left at the bottom and caught
among the bowlders is the **formacao. ** There are more than thirty
minerals, some of which are always found in it. Among them are
tourmaline, specular iron, disthene, rutile, gold, and various phos-
phates. The presence of these shows that the existence of the dia-
mond among them is probable. The **formacao" is prospected for
in the dry season, and as soon as found is dug out and piled near
by the water. When the rains interrupt the digging, the miners
work up the gravel. The operation is very simple. The gravel is
first washed in a **bacu," an excavation a yard wide and a yard
and a half long on the bank of a pond or stream. Its lip is a few
inches above the surface of the water and it deepens slightly to
the rear. A cubic foot or more of gravel is placed in the back
end and the workman dashes water against it out of a large concave
wooden plate, giving it a peculiar rotary fling. This rapidly sepa-
rates the lighter and larger stones from the smaller and heavier ones.
When concentration by this rough method is as complete as possible,
the gravel is worked with the **batea." This unique instrument is
a wooden dish about 30 inches in diameter, with a sort of pit at the
bottom. Filling the **batea" with the concentrate and water,
the workman agitates the contents, whirling and shaking them, mean-
while pouring and scraping the lighter gravel from the top as fast
as he separates it. The operation is very similar to old-fashioned
gold panning, but requires even greater skill, on account of the
danger of losing diamonds. It is said that a man may be a first-
rate gold panner and yet be useless for diamond washing. At the end
of the process, the diamonds are simply picked out by hand from
the remaining minerals. Their peculiar luster makes them easily
recognizable even by a tyro. The Brazilian method of washing
alluvial gold is substantially that described above. By its use,
practically all the diamonds and placer gold which Brazil has pro-
duced have been obtained. The native Diamantina miners know no
better method.

At present, the small stream washings in the Diamantina district
are not important or productive. Two hundred years of search has
exhausted most of them. Those who work them are usually men
with little or no capital. They go in small parties and work some-
what at random, trusting to the chance of finding virgin gravel and
making a rich haul. The rewashing of ancient concentrates of the
old workings is also extensively pursued.

The second method of mining is that practiced in the beds of the
larger streams. The opening of one of these mines is an extensive



Digitized by



Google



DIAMOND AND GOLD MINING IN MINAS GERAKS. 539

and complicated undertaking, reguiring the employment of thou-
sands of dollars and hundreds of men. At the beginning of the dry
season, a spot is selected which is believed from tradition or ancient
documents to be virgin. Just above the spot selected, a rude dam
is erected and also a sluice around it, through which the waters of
the river are turned. The bed thus exposed is usually found to be
of sand, largely the detritus of ancient workings. This sand is car-
ried out a shovelful at a time in little wooden pans on the tops of
negroes' heads. Naturally, such a process is tedious and expensive.
The work could be done many times more cheaply and quickly with
dump carts or even with wheelbarrows. From time to time, attempts
have been made to introduce them ; but they have not been success-
ful, owing to the conservatism of the native miners. The excava-
tion is often carried to a depth of 30 or 40 feet before bed rock,
where the **formacao" is to be found, is reached. The hundreds of
workmen climbing the slopes of the hole in long lines, each balanc-
ing a pan of earth upon his head, look like ants following their paths
in and out of a hill. The work is done in great haste, because the
first considerable rains in September or October wash away the whole
structure and fill up the excavation. The water that percolates into
the pit is pumped out with rude pumps worked by overshot wheels,
a portion of the river being diverted from the sluice for this pur-
pose. These pumps are simply wooden tubes, in which work leather
buckets' opening upward. A stream of water is kept continually
pouring down from the top to keep them running, otherwise they
would not draw. The construction of the sluice, dams, and wheels
shows considerable primitive engineering skill. No nails or iron
are used. The joints are mortised or bound together with vines.
The builders have no idea of exact measurements, even the slope of
the sluice being determined by the eye alone. Nevertheless, such
is their inherent skill that their work nearly always serves its pur-
pose. However, they are unequal to difficult and novel problems.
For example, one famous spot in the Jequitinhonha called the
**Pocao (pothole) de Moreira," reputed to be virgin and fabulously
rich, was unsuccessfully attempted several times in the early part of
this century. Every time before the bottom was reached the rains
came and destroyed what had been done. A few years ago, Antonio
de Lavandeyra, a Cuban engineer, by the use of modern methods
and pumps, succeeded in reaching and uncovering the bed rock.
The practical results were a good example of the discouraging uncer-
tainty of diamond mining. Only four diamonds were found. It
is now believed that one of the early contractors, in the good old
days before the **formacao*' in the Jequitinhonha had been covered
up with sand, had exposed or dredged the spot and taken out all



Digitized by



Google



540 DIAMOND AND GOLD MINING IN MINAS GERAES.

the diamonds, and then had not thought it necessary to make any
record of his doings for the Government or posterity.

The whole bed of this richest of all diamond rivers, from its
source to Mendanha, some 50 miles below, has probably been worked.
Below that point, the valley is too broad and the bed too much
choked with sand to permit operations of the kind I have just been
describing.

The gravel found is carried out of the excavation and placed in
piles until the enforced leisure of the wet season gives a convenient
opportunity to wash it. If the ground is virgin, the miners are
likely to get a rich reward; if the gravel has been washed before,
they lose all they have spent. The river mining is usually carried
on by a local expert, who forms a company, to which his speculative
neighbors and friends subscribe. No foreign capital is employed
in it.

The third kind of diamond mining is from the **gupiaras,*' or
deposits of gravel found on the slopes and sides of the valleys. The
finding of these is largely a matter of chance. Some of them have
proved wonderfully rich. From one, the **Gupiara da Lava-Pes,"
more than 160,000 carats were taken in one season. It covered an
area of not more than 6 acres, and was probably the richest small
deposit of diamonds ever found. Even this was not thoroughly
worked over. Last year, two negroes doing a little casual washing
on their own account one Sunday found 20 carats.

The fourth kind of mining is that in the conglomerates and beds
of clayey rock which are found high up in the serra. These beds
are almost certainly the source of the alluvial diamonds, in just the
same way that quartz veins are the source of placer gold. Contra-
band miners discovered that they were diamondiferous. These dar-
ing fellows, mining by stealth and in small parties in the little
streams, followed them up to their sources.- To their surprise, they
continued to find diamonds clear up to the top of the serra and
finally in the country rock itself. The conglomerate, or clay, is, of
course, far less rich than the alluvial gravel in which the gems have
been concentrated by the action of water, but in compensation, the
quantity is much greater. Much of it is hard and compact and dif-
ficult to work, but some is soft enough to wash away readily in run-
ning water. After the Brazilians had taken the diamonds out of the
weathered surface, they proceeded to work the deeper deposits in
the following manner, which is the only method they know:

They collected rain water in pools on the tops of the plateaus
and led it by ditches to a favorable outcrop of the diamondiferous
deposit, there cutting out great gullies in the soft rock. The action
of the water separated the **formacao" from the bulk of the d6bris,



Digitized by



Google



DIAMOND AND GOLD MINING IN MINAS GERAES. 54I

and this was further treated in much the same way as the alluvial
gravel. This method was extremely slow and vexatious, because
sufficient water for effectively washing away the masses of rock could
only be collected a few days in each year. Ten working days is a
good average for a twelvemonth, and whole seasons pass without
a single day's washing. Nevertheless, fortunes have been made in
this kind of mining; and some of these **chapada** mines, as they
are called, have been continually worked for nearly a century.

A French corporation, the **Companhia da Boa Vista," has re-
cently purchased a large tract of conglomerate-bearing plateau
where mines already existed, worked as I have just described, 8
miles from Diamantina, and has undertaken its exploitation on a
large scale and by modernized methods. Mr. A. Lavandeyra, an
American citizen of Cuban birth, a graduate of the Troy Polytech-
nique School and formerly one of the engineers of the Panama
Canal, is the managing director in charge. Their conglomerate is
found near the surface of the **chapada," or plateau, of Boa Vista
at an elevation of 4,300 feet above the sea. The installation now be-
ing completed consists, briefly, of a reservoir on one of the higher
levels of the plateau, the water from which is to be conducted by
pipes wherever it is needed for washing. This reservoir is connected
by a pipe 10 inches in diameter with another reservoir half a mile
away and 280 feet below the first. The latter is made by a dam
across a small stream, which furnishes a constant supply of water
sufficient for washing, but not large enough to run the pumps.-
These have a capacity of 90 liters a second and are operated by elec-
tric motors, which are connected by a wire running down the moun-
tain side to a point 1,040 feet lower. Here is the power station in
the valley of a large stream, the Santa Maria. The dynamos are
operated by a 500-horsepower Pelton wheel, and this in turn by a
pipe 20 inches in diameter, a mile long, and with a fall of 340 feet.
It is supplied from a dam built across a narrow gorge of the river.
The machinery for separating the diamonds from the washed con-
glomerate is specially constructed and was built in Europe.

This is the first and, so far, the only noteworthy attempt to apply
modern scientific methods to diamond mining in Brazil. The engi-
neering and practical difficulties which Mr. Lavandeyra has success-
fully surmounted have been very great. In engineering features, the
plan is unique and original. The same conditions are to be encoun-
tered in no other kind of mining, and the methods of meeting them had
to be thought out from the beginning. Even the diamond mining of
South Africa affords no precedents. Skilled mechanics are unknown
in the diamond district. Workmen have to be taught to use wheel-
barrows or hammers and how to rivet pipes. There are no roads.



Digitized by



Google



542 DIAMOND AND (lOLD MINING IN MINAS GERAES.

and the miner must build his own. The difficulties of transporting
heavy dynamos and castings on wooden-wheeled ox carts over moun-
tain trails for more than loo miles are incredible. Iron working,
except horseshoeing, is unknown in that region, so repairs and
changes are impossible to be made on the ground. The Boa Vista
Company had the pipe cut in short sections and brought up on mule
back. The native miners are very incredulous as to the success of
the enterprise. They can not understand how water can be carried
in a little copper wire. Work was begun last March and is not yet
finished. That the enterprise will be successful seems almost certain,
unless the reasonable expectations of the company as to the amount
of diamonds the conglomerates contain prove to be unfounded.

The electrical machinery was furnished by 'the General Electric
Company, of New York. Should the Boa Vista mine be a success,
it is sure to be followed by others, for there are many other diamond-
bearing beds in the Diamantina district, and doubtless in the other
districts as well. A large field for the sale of American machinery
and for independent American enterprise would then be opened up.
American miners are especially fitted for the work. The Boa Vista
Company has, besides Mr. Lavandeyra, two American electricians
engaged in the installation and operation of the electrical machinery.

Titles to diamond mines in Brazil are usually based upon dis-
covery, registration, and the payment of a small fixed tax to the
State. There is also a nominal requirement that a certain amount of
work be done in the claim each year. Rights lapse upon failure to
pay the tax or upon abandonment. Mining claims are very gen-
erally owned in the district. Nearly every man one meets has a
claim which he is sure will make his fortune. The smaller miners
roam almost at will over the country prospecting, and have the tacit
encouragement of the owners. The latter, however, promptly as-
sert their ownership and dispossess the squatters if these are fortu-
nate in making a good find and unlucky enough not to be able to
keep it secret. The owners get their claims prospected without
expense.

The brute diamonds are usually sold by the small miners to
buyers from Diamantina, who frequent the hamlets near the mines.
Many are, however, brought directly to the city and sold to the gen-
eral merchants. The prices of these rough diamonds vary largely
with the fluctuations of the currency and with the quality and size
of the stones and the necessities of the seller. Seventy milreis ($io)
a carat is an approximate average. Rezende & Co., of Rio de
Janeiro, are the largest dealers. Practically all the stones which do
not remain in Brazil are sent to Paris and London. Although the
United States is the greatest diamond-consuming market in the



Digitized by



Google



DIAMOND AND GOLD MINING IN MINAS GERAES. 543

world, taking about one-half of the South African product, very
few Brazilian stones are imported directly. I am inclined to believe
that a favorable opportunity exists for diamond buyers from the
United States to enter this market, instead of competing for them
in Europe. Besides, this would benefit the diamond-cutting industry
in the States. Brazilian diamonds are worth, on an average, nearly
50 per cent more than the Cape stones, being, as a ijule, whiter.
However, all colors are found, and the rose, wine colored, and blue
varieties are much sought for and valued.

From the appearance of a brute diamond, little can be told as to
its luster and freedom from flaws after cutting. A greenish exterior
often indicates that the stone will cut white, but there is no certain
guide. Therefore, the buying of rough stones is very speculative,
and it is unsafe for even an expert to buy single uncut stones.

It is impossible to obtain exact information as to the present out-
put of the Diamantina field. No statistics are kept, and the buyers
are so numerous and scattered that they can not be reached. The
same was true of the ancient production. The statistics which have
from time to time been published by Europeans are merely estimates.

The extensive mining of diamonds in Brazil began in 1740, when
the first lease was made by the Portuguese Government. The period
of greatest production was between 1750 and 1770, under Caldeira
Brant, sole contractor, and his successors. These contractors made
a practice of concealing from the Government the amount of their
production, and of using a greater number of slaves than that to
which they were limited by their contracts. Tradition alone pre-
serves an approach to the truth as to the extent of their operations.
If it can be trusted, .the production of 1740 to 1750 was not less than
50,000 carats a year, and that of 1750 to 1770, 150,000 a year. From
1 77 1, when the Government began extraction on its own account,
until that system fell into disuse, we have fairly trustworthy statistics
of the Government production. But contraband mining flourished
at the same time, and its extent can only be estimated. Between
1 77 1 and 1795, ^^^ Government mined 40,000 carats a year. For the
next ten years it fell to 20,000 carats a year. During this period, the
contraband production was believed to be as large as the legal.
From 1807, the disorganization of the Portuguese administrative
system and the increasing sentiment of local liberty in Brazil, both
largely due to the Napoleonic wars and the flight to Brazil of the
royal family, sapped the efficiency of the Government **extraccao,"
and private mining gradually but completely took its place. During
the present century, the production has varied from year to year.
The freedom of mining has tended to increase it; but, on the other
hand, alluvial mining has on the whole decreased with the exhaustion



Digitized by



Google



544 DIAMOND AND GOLD MINING IN MINAS GERAES.

of the easily worked beds and the known localities. This latter
tendency has not been counteracted by the introduction of improve-
ments in the method of working, nor by any great energy in search-
ing for fresh fields. Sir Richard Burton, who visited Diamantina in
1867, reported it to be very prosperous and quotes an estimate, made
by an exporter,-of an annual production of 80,000 carats. The best
local estimates of the present output approximate 25,000 to 30,000
carats a year.

Until thirty years ago, there was no diamond cutting in the dis-
trict. It is now carried on extensively in Diamantina and the neigh-
boring villages. The quaint little mills are supplied with power by
overshot water wheels. The process of cutting does not differ from
that employed in Europe. The machinery comes from Holland.
The work is fairly good and very cheap. Most of the stones are
cut into the brilliant shape. In this, they lose about 50 per cent.
The rose shape, which is the more usual among European cutters,
loses 15 per cent more by the making of an additional row of facets.

Another prosperous industry in Diamantina is the manufacture
of gold jewelry. The workmen are mostly Portuguese. They are
industrious and skillful. The designs are old-fashioned, and filigree
is popular. The jewelry is peddled about the country and meets
with ready sale, although relatively expensive. There would seem
to be a favorable opening for the introduction of cheap and plated
jewelry to compete with it.

My report upon the other mining industries of Minaswill be some-
what meager, for the time at our disposal did not permit more than
a cursory examination. At Diamantina our party visited the site of
the existing washings and the old abandoned workings, which are
much more extensive. At Ouro Preto we were shown through the
school of mines by its professors and were given much valuable in-
formation. At Morro Velho we saw in operation the largest gold
mine in Brazil.

GOLD.

The principal gold-producing territory of Minas begins 250 miles
north of Rio de Janeiro and extends along the Serra da Espinhaco
as much farther toward the north. Gold is found and mined in other
localities, but the bulk of the past and present production of Brazil
is from this district. The discovery was made in 1693 by slave hunt-
ers from the province of Sao Paulo, who were after Indians. There
was an immediate inrush of adventurers, and by the beginning of
the eighteenth century thousands of them with their slaves were scat-
tered all over the territory which has since been so productive. Until
1760, the production continued to increase rapidly, in spite of the
exorbitant and tyrannical exactions of the Government and the rude



Digitized by



Google



DIAMOND AND GOLD MINING IN MINAS GERAES. 545

and superficial methods of mining employed. At its maximum, it
amounted to more than 320,000 ounces a year. After 1760 it de-



Online LibraryUnited States. Dept. of Commerce and Labor United States. Bureau of Foreign CommerceConsular reports, Issues 224-227 → online text (page 64 of 92)