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View from Aguada Nova fort

From the neighboring hill of Aguada Nova, we descended to a deep grotto, and after five overly painful leagues walking through the savannah and the scrub, on a rock ledge, we found ourselves at the goal of our excursion, Gupiara or Calhau, a village of few houses of sape where the stone diggers live.

Aracuai Valley

From there we enjoyed a vast panorama over the jungles of the Aracuai Valley, where the Ribeirao do Calhau flows, which is born here. The mountain's orogeny reveals a coarse-grained, off-white granite that contains little white

Black tourmaline

mica, but a lot of black tourmaline, often crystallized into long prisms. Not infrequently, granite alternates with a gneiss of constituent elements of the same species, whose contemporary formation is evident. Now the granite appears distinctly, sometimes lined with a thick twelve-foot layer of a gray or white weevil whose main constitution is quartz.

Both in the stony bed of Ribeirao Calhau and in carboniferous debris are particularly greenish-white, whitish-ocher yellow, lime-yellow crystals or light-green azure, grass-green and aquamarine),

Blue grenade or blue garnet

also precious white and light blue grenades and topaz. Therefore, these stones correspond with diamonds in that they never appear in the primitive matrix. With them are found in the pebble weevil and residues many fragments of lidite and a glassy quartz, translucent or milky white, equally abundant. The first of these, when rounded, are called beans as in the Diamantino District.


In some chrysoberyls we thought we saw clinging traces of quartz and granite, and it is very likely, therefore, because of all the local conditions, that these beautiful stones originate in the quartz strands of granite. Likewise, perhaps the grenades, which are found here, or even granite quartz.

Chrysoberyl crystal

Chrysoberyl crystals (double-sided pyramid, blunt on both vertices), especially those of good size, are extremely rare; most abundant, however, are the beautifully pure dodecahedrons of the grenades. The largest chrysoberyl found here appears to weigh 48 octaves. The diggers extract these stones, such as the diamonds, from sand and gravel from Ribeirao Calhau, and from the carboniferous remains that lie in the excavated pits and square mines.

From Gupiara we continued, for a league ahead, until the Sant'Ana stream, where we stayed overnight in the house of a knight. The rock on which this

Red feldspar

stream slides is equally granitic, sometimes with large amounts of a flesh-red feldspar, sometimes coarse-grained, sometimes fine-grained. In white quartz lies a beautiful