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Sec. II, Ch. 4: The Borneo Diamond

Sec. II, Ch. 4: The Borneo Diamond Page of 366 Sec. II, Ch. 4: The Borneo Diamond Text size:minus plus Restore normal size   Mail page  Print this page
Borneo Diamonds.
103
At all these localities the Diamonds are found with gold and, in some cases, with platinum, in the sands of the rivers; and also in beds of clay, sand and gravel, some­times at a considerable depth. A blue or bluish-grey Corundum, known as Batu timahan, is said to be a constant companion of the Diamond, the natives regarding it as an attendant on the "Prince," as they term the more precious stone. Dr. Verbeek thinks that the original matrix of the Diamond, which yielded the stones occurring in the drifts, is to be found among the older slaty and schistose rocks ; whilst the late Prof. Carvill Lewis suggested that the Dia­monds had been brought up from depths by the serpentine, or altered peridotite, which appears to be not uncommon in the Diamond districts of Borneo.
The natives wash the sands of the rivers in small bowls, and become so expert in detecting the valuable stones that they can separate the Diamonds from the worthless minerals, even when so small as to escape observation by Europeans. The drifts are worked by means of small shafts sunk through the overlying deposits, and the Diamond-yielding bed is then followed by little tunnels driven in a very primitive manner. Considerable improvements have, however, been introduced by the Chinese, who are extremely skilful and economical miners. Of late years Europeans have entered the field, and Diamond-mines in Tjempaka are now worked by French engineers ; but the washing of the Diamond-earth after its extraction is said to be still done on the old Malay system.
The Diamonds of Borneo usually occur in crystals, presenting the form of the octahedron, the cube and the rhombic dodecahedron. If they present bright faces and sharp angles, and are considered by the natives tó need no
Sec. II, Ch. 4: The Borneo Diamond Page of 366 Sec. II, Ch. 4: The Borneo Diamond
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