Very
rich gold quartz has been brought from Carabaya on Lake Titicaca; and
recently considerable deposits both alluvial and in veins have been
opened at Caratal in Venezuela and at St. Elie in French Guiana, which
are interesting as proving the actual existence of Raleigh's Eldorado.
In
Brazil the principle gold mines are upon veins in clay slate, and a
peculiar class of rocks known as Jacotinga or Itabirite, and which arc
mixtures of quartz, chlorite, and specular iron ore, the latter often
occurring in large mirror-like crystals several inches across. The gold
occurs almost entirely in pyritic minerals, being most abundant in
ordinary iron pyrites, and less so in magnetic and arsenical pyrites,
free gold being rarely seen. (See Brazil, vol. iv., p. 224,)
In
Africa the chief gold-bearing localities are on the west coast—gold
dust derived from alluvial washings forming an article of export from
many of the trading stations along the Guinea coast. Latterly, alluvial
deposits have been worked in the mountains of Transvaal, in the
Leydenburg district (25° S. lat. 31* E. long.), producing coarse
nuggetty gold in masses up to 11 lb weight, and in a few cases
gold-bearing quartz has been found in veins in talcose schist and
quartzite, closely associated with eruptive masses of diorite. The age
of these rocks is considered by Dunn (a) to be Silurian or
Devonian, and the observed phenomena to be similar to those generally
observed in Australia. The upper valley of the Nile produces a little
gold in Abyssina and Nubia, the latter being the land of gold of the
old Egyptains. Very extensive ancient mines have been described by
Linant Bey in the district known as Attaki or Allaki on the Red Sea,
situated about 120 miles back from Ras Elba, the headland midway
between Berenice and Sauwakin. These are probably the same mines that
were described by Diodorus Siculus, and one of the oldest topographical
documents known, a map or itinerary of the route to them from the Nile,
is preserved at Turin. In the reign of Setee I., of the 19th dynasty,
wells were opened along this rout';, in order that the mines, that were
then of very great antiquity, might be reopened. (6) Similar
ancient gold mines have recently been discovered by Burton in the land
of Midian, on the east coast of the Gulf of Akaba.
The
gold districts of Australia cover a very considerable area, extending
from the east side of the continent for about 20° of latitude (18° to
38° S.), the more important deposits being those of Victoria in the
South. The principal districts are in Victoria,'—Ballarat, Castlemaine,
and Sandhurst, lying west and north from Melbourne, and Beechworth near
the Murray River to the northeast. In New South Wales the gold-fields
are scattered over the entire length of the colony from north to south,
the more important districts lying between the 32nd and 36th parallels
of S. lat. on the western side of the Australian cordillera, on the
upper tributaries of the Macquarie and Lachlan rivers, the centre being
about the town of Bathurst. This is known as the western districts.
Another group, known as the northern district, is on the eastern side
of the mountains near the Queensland boundary, in 29° S., Rocky River
being the principal locality: while the southern district includes
Braidwood, Adelaide, Tumbarumba, and other localities near the Murray
River. In Queensland the chief localities are, commencing on the south,
Gympie and Kilkevan near Maryborough, 26° S. lat.; a group extending
about 50 miles north and south of Rockhampton, in 24° 30' S. lat., all
near the coast; Eastern River, Hurley, and Peak Downs about 300 miles
inland on the 23rd parallel; and Colmenny and Gilbert on a stream
running in to the Gulf of Carpentaria, besides numerous others. In all
those localities two principal kinds of deposits are observed, namely,
auriferous quartz veins traversing slates of Silurian and Devonian age,
which are in intimate relation with masses of diorite and other
eruptive rocks; and gold-bearing drifts of Miocene or even newer
Tertiary date, derived from
