190 
VISIT TO the aoLD-WAsnrsros. 
grained, of a bluish tint, and traversed by veins of ealea* 
reous spar of dazzling whiteness. These calcareous masses 
must not be confounded with the very recent depositions of 
tufa, or carbonate of lime, which fill the plains of the Tuy ; 
they form beds of mica-slate, passing into talc-slate.* The 
primitive limestone often simply covers this latter rock in 
concordant stratification. Very near the llato the talcose 
slate becomes entirely white, and contains small layers of 
soft and unctuous graphic ampelite.t Some pieces, desti- 
tute of veins of quartz, are real granular plumbago, which 
might bo of use in the arts. The aspect of the rock is very 
singular in those places where thin plates of black ampelite 
alternate with thin, sinuous, and satiny plates of a talcose 
slate as white as snow. It would seem as if the carbon and 
iron, which in other places colour the primitive rocks, are 
here concentrated in the subordinate strata. 
Turning westward we reached at length the ravine of 
gold (Quebrada del Oro). On examining the slope of 
a hill, we could hardly recognize the vestige of a vein of 
quartz. The falling of the earth caused by the rains bad 
changed the surface of the ground, and rendered it impos- 
sible to make any observation. Great trees were growing- 
in the places where the gold-washers had worked twenty 
years before. It is probable that the mica-slate contains 
here, as near Goldcronach in Franconia, and in Salzburgh, 
auriferous veins; but how is it possible to judge whether 
they be worth the expense of being wrought, or whether 
the ore is only in nodules, and in the less abundance in 
proportion as it is rich? Wo made a long herborization 
in a thick forest, extending beyond the llato, and abound- 
ing in eedrelas, browneas, and fig-trees with nymphrea 
leaves. The trunks of these last are covered with very 
odoriferous plants of vanilla, which in general flower only in 
the month of April. We were here again struck with those 
ligneous excrescences, which in the form of ridges, or ribs, 
augment to the height of twenty feet above the ground, the 
thickness of the trunk of the fig-trees of America. I found 
* Talkschiefer of Werner, without garnets or serpentine ; not eurite or 
iveisstein. It is in the mountains of Buenavista that the gneiss manifests 
a tendency to pass into eurite. 
f Zcichensclnefer. 
