tos
of the total of 1,180 contos. The other outlets of importance were
Belgium, Sweden, and Japan, the respective amounts of their purchases
being 220, 74 and 69 contos.
EMERALDS
The
extremely rare Oriental Emerald, a designation now in disuse, is a
green corundum. The" Beryl Emerald is found in South America and is the
variety which made famous the Muso mines in Colombia which today are
closed. In all cases the coloring matter is chromium.
The discovery of corundum emeralds has been reported in the state of Goiaz but no further details are available.
The
emerald occurs in association with basic rock (talcum schist) in
Itaberai in the Serra das Lages in the state of Goiaz. The alluviums of
this region have an extension of several kilometers.
The
emerald appears in the state of Minas Gerais in the regions of
Conceicao, Itabira and Ferro where it is found in mica schist cut by
pegmatite veins.
Two
regions in the state of Baia at present produce emeralds, Vila Nova in
the municipality of Conquista, near the Rio Gaviao, and Serra das Eguas
in the municipality of Brumado. In these localities they are found in
veins of magnesite, constituted of large rhombohedrons of the magnesite
itself and of quartz, emerald, tourmaline, topaz, etc. This type of
occurrence is very similar to that found in Colombia, the leading
producing district of which at present in Chivor.
In
the Serra das Eguas there are alluviums with emerald deposits covering
an area of 2,000 meters ,by 200 meters. The present operations however
are limited to a zone of only 200 meters by 300 meters, partly in the
veins, but for the most part in the alluvial deposits. It is possible
to prospect these deposits by means of a line of shafts following the
maximum declivity. Excellent gems were discovered in this manner at
Brumado in the state of Baia.
Ordinary
Brazilian emeralds range from 50 milreis to 200 milreis a gram while
cut stones vary from 50 milreis to 500 milreis a carat, Eppler however
mentions prices up to 10,000 milreis a carat for some stones.
CORUNDUM
Corundum
is an anhydrous aluminum with a hardness of 9, density of 4, and a
refraction index of 1.765. It occurs in short bipyramidal prisms. The
blue variety is known as sapphire or "engineers' stone" the coloring of
which is due to the presence of iron and titanium, while the red stone
is the ruby or "lawyers' stone", the coloring of which is attributed to
the chromium element .
