Personal Narrative Of Travels To The Equinoctial Regions Of America During The Years 1799-1804 - Volume 3 - By Alexander Von Humboldt And Aime Bonpland.
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Though The Celebrity Of The Riches Of Spanish Guiana Is Chiefly
Assignable To The Geographical Situation Of The Country And
The errors
of the old maps, we are not justified in denying the existence of any
auriferous land in the
Tract of country of eighty-two thousand square
leagues, which stretches between the Orinoco and the Amazon, on the
east of the Andes of Quito and New Granada. What I saw of this country
between the second and eighth degrees of latitude, and the sixty-sixth
and seventy-first degrees of longitude, is entirely composed of
granite, and of a gneiss passing into micaceous and talcous slate.
These rocks appear naked in the lofty mountains of Parima, as well as
in the plains of the Atabapo and the Cassiquiare. Granite predominates
there over the other rocks; and though, in both continents, the
granite of ancient formation is pretty generally destitute of
gold-ore, we cannot thence conclude that the granite of Parima
contains no vein, no stratum of auriferous quartz. On the east of the
Cassiquiare towards the sources of the Orinoco, we observed that the
number of these strata and these veins increased. The granite of these
countries, by its structure, its mixture of hornblende, and other
geological features alike important, appears to me to belong to a more
recent formation, perhaps posterior to the gneiss, and analogous to
the stanniferous granites, the hyalomictes, and the pegmatites. Now
the least ancient granites are also the least destitute of metals; and
several auriferous rivers and torrents in the Andes, in the Salzburg,
Fichtelgebirge, and the table-land of the two Castiles, lead us to
believe that these granites sometimes contain native gold, and
portions of auriferous pyrites and galena disseminated throughout the
whole rock, as is the case with tin and magnetic and micaceous iron.
The group of the mountains of Parima, several summits of which attain
the height of one thousand three hundred toises, was almost entirely
unknown before our visit to the Orinoco. This group, however, is a
hundred leagues long and eighty broad; and though wherever M. Bonpland
and I traversed this vast group of mountains, its structure seemed to
us extremely uniform, it would be wrong to affirm that it may not
contain very metalliferous transition rocks and mica-slates
superimposed on the granite.
I have already observed that the silvery lustre and frequency of mica
have contributed to give Guiana great celebrity for metallic wealth.
The peak of Calitamini, glowing every evening at sunset with a reddish
fire, still attracts the attention of the inhabitants of Maypures.
According to the fabulous stories of the natives, the islets of
mica-slate, situate in lake Amucu, augment by their reflection the
lustre of the nebulae of the southern sky. "Every mountain," says
Raleigh, "every stone in the forests of the Orinoco, shines like the
precious metals; if it be not gold, it is madre del oro (mother of
gold)." Raleigh asserts that he brought back gangues of auriferous
white quartz ("harde white sparr"); and to prove the richness of this
ore he gives an account of the assays that were made by the officers
of the mint at London.* (* Messrs.
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