Personal Narrative Of Travels To The Equinoctial Regions Of America During The Years 1799-1804 - Volume 2 - By Alexander Von Humboldt And Aime Bonpland.
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It Is Not The Same In
The Mixtures Of Serpentine And Granulated Limestone.)
The grunsteins of Tucutunemo, which we consider as constituting the
same formation as the serpentine rock, contain veins of malachite and
copper-pyrites.
These same metalliferous combinations are found also
in Franconia, in the grunsteins of the mountains of Steben and
Lichtenberg. With respect to the green slates of Malpaso, which have
all the characters of transition-slates, they are identical with those
which M. von Buch has so well described, near Schonau, in Silesia.
They contain beds of grunstein, like the slates of the mountains of
Steben just mentioned.* (* On advancing into the adit for draining the
Friedrich-Wilhelmstollen mine, which I caused to be begun in 1794,
near Steben, and which is yet only 340 toises long, there have
successively been found, in the transition-slate subordinate strata of
pure and porphyritic grunstein, strata, of Lydian stone and ampelite
(alaunschiefer), and strata of fine-grained grunstein. All these
strata characterise the transition-slates.) The black limestone of the
Morros de San Juan is also a transition-limestone. It forms perhaps a
subordinate stratum in the slates of Malpaso. This situation would be
analogous to what is observed in several parts of Switzerland.* (* For
Instance, at the Glyshorn, at the Col de Balme, etc.) The slaty zone,
the centre of which is the ravine of Piedras Azules, appears divided
into two formations. On some points we think we observe one passing
into the other.
The grunsteins, which begin again to the south of these slates, appear
to me to differ little from those found north of the ravine of Piedras
Azules.
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