NON-METALLIC MINERALS
97
principal
sources of monazite, however, are Espirito Santo and Baia. Several bags
of the sand of the state of Espirito Santo analyzed as follows: Umenite
— 71.6%; Monazite — 6.0%; Magnetite — 0.2%; Zircon — 13.0%; Quartz —
6.0% and the remainder, mixed products. Testing the monazite
separately, it was found that the average thorium oxide content in six
samples amounted to 6.2% while that of cerium, lanthanium and didymium
oxide totalled 60.7%. It is the practice to separate the quartz from
the sands by means of washing while the ilmenite, monazite and zircon
are later extracted by means of an elec-tro-magnet.
The sands of Comoxatiba of the municipality of Prado in the state of
Baia contain 5.75% thorium while those of Bandeira de Melo have as much
as 10.5%. The sands of Mucuri vary greatly having a minimum of 5 and a
maximum of 6%. The state average however, is low, ten samples testing with
only 3.33% thorium oxide.
Samples of the mineral of the state of Estado do Rio show that the sands contain 5.87% thorium oxide.
In the state of Minas Gerais, monazite is found generally in river beds. its of this mineral are available.
In more than 20 years of the export history of this product, the largest
shipment was that of 1920, year in which the total was 1,153 metric tons. Since
then shipments have been exceedingly irregular averaging 221 metric tons in
the 1920-9 decade, 144 metric tons in the 1930-4 quinquennium and 158 metric
tons in the 1935-9 period the largest since 1920 being that of 1937 in which
reports of monazitic sands amounted to 417 metric tons, Germany being the sole
market for the mineral. In 1938, there was a decrease to 323 metric tons, the
chief market in that year being France which purchased 223 tons. The United
States was the only market in 1939, year in which the total was but 48 metric
tons. A slight increase was evidenced in 1940, the total of 180 metric tons
Being shipped to the United States.
The unit price of the exports in 1937 was 197 milreis per metric ton,
that of 1938 being the same and that of 1939 — 199 milreis thus being one of the
most stable minerals in price in the export trade. In 1940, however, there was
an abrupt rise to 743 milreis. It may be noted in this connection that the mine
price in the same year was 500 milreis.
There
are no imports of products based on monazite or its derivatives which
are classified separately to permit a study of their prices.
13. PRECIOUS STONES
GENERAL SURVEY
Due
to the sporadic nature of production of all gems other than dia-monds
and carbonados, it is difficult to place the actual production of
Brazil. Suffice it to say, however, in this connection, that the
exports of diamonds and
