In That Part Of The Sierra Parime Which M. Bonpland And Myself Visited, Gneiss Forms A Less Marked Zone, And Oscillates More Frequently Towards Granite Than Mica-Slate.

I found no garnets in the gneiss of Parime.

There is no doubt that the gneiss-granite of the Orinoco is slightly auriferous on some points.

(c) MICA-SLATE, with clay-slate (thonschiefer), forms a continuous stratum in the northern chain of the littoral Cordillera, from the point of Araya, beyond the meridian of Cariaco, as well as in the island of Marguerita. It contains, in the peninsula of Araya, garnets disseminated in the mass, cyanite and, when it passes to clayey-slate, small layers of native alum. Mica-slate constituting an independent formation must be distinguished from mica-slate subordinate to a stratum of gneiss, on the east of Cape Codera. The mica-slate subordinate to gneiss presents, in the valley of Tuy, shelves of primitive limestone and small strata of graphic ampelite (zeicheschiefer); between Cabo Blanco and Catia layers of chloritic, granitiferous slate, and slaty amphibole; and between Caracas and Antimano, the more remarkable phenomenon of veins of gneiss inclosing balls of granitiferous diorite (grunstein).

In the Sierra Parime, mica-slate predominates only in the most eastern part, where its lustre has led to strange errors.

The amphibolic slate of Angostura, and masses of diorite in balls, with concentric layers, near Muitaco, appear to be superposed, not on mica-slate, but immediately on gneiss-granite. I could not, however, distinctly ascertain whether a part of this pyritous diorite was not enclosed on the banks of the Orinoco, as it is at the bottom of the sea near Cabo Blanco, and at the Montana de Avila, in the rock which it covers.

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