lavas; one, in particular, in the Riversdale
Division near the southern coast, being occupied by a melilite-basalt.
It is quite clear that the occurrence of the diamond in the S. African
pipes is quite different from the occurrences in alluvial deposits
which have been described above. The question of the origin of the
diamond in S. Africa and elsewhere is discussed below.

The River Diggings on the Vaal river are still worked upon a small
scale, but the production from this source is so limited that they are
of little account in comparison with the mines in the blue ground. The
stones, however, are good; since they differ somewhat from the
Kimberley crystals it is probable that they were not derived from the
present pipes. Another S. African locality must be mentioned;
considerable finds were reported in 1905 and 1906 from gravels at
Somabula near Gwelo in Rhodesia where the diamond is associated with
chrysoberyl, corundum (both sapphire and ruby), topaz, garnet,
ilmenite, staurolite, rutile, with pebbles of quartz, granite,
chlorite-schist, &c. Diamond has also been reported from kimberlite
"pipes" in Rhodesia.

_Other Localities._--In addition to the South American localities
mentioned above, small diamonds have also been mined since their
discovery in 1890 on the river Mazaruni in British Guiana, and finds
have been reported in the gold washings of Dutch Guiana. Borneo has
possessed a diamond industry since the island was first settled by the
Malays; the references in the works of Garcia de Orta, Linschoten, De
Boot, De Laet and others, to Malacca as a locality relate to Borneo.
The large Borneo stone, over 360 carats in weight, known as the Matan,
is in all probability not a diamond. The chief mines are situated on
the river Kapuas in the west and near Bandjarmassin in the south-east
of the island, and the alluvial deposits in which they occur are
worked by a small number of Chinese and Malays. Australia has yielded
diamonds in alluvial deposits near Bathurst (where the first discovery
was made in 1851) and Mudgee in New South Wales, and also near Bingara
and Inverell in the north of the colony. At Mount Werong a stone
weighing 29 carats was found in 1905. At Ruby Hill near Bingara they
were found in a breccia filling a volcanic pipe. At Ballina, in New
England, diamonds have been found in the sea sand. Other Australian
localities are Echunga