Diamond Mines of the World: Borneo's Landak Diamonds
Borneo's Diamond Mining History - Cempaka & Landak
Article Copyright © 2009 AllAboutGemstones.com
During the height of the indian diamond trade in the 15th through 19th centuries, diamonds from the Landak region of Borneo (Kalimantan) were particularly prized for their brilliance, and their unique range of colors. Borneo was part of the Dutch colonial empire (Dutch East Indies) from the 1600s to the early 1800s, when the island came under the control of the British North Borneo Company.
Borneo is now divided between Indonesia (the "Kalimantan" region to the south), Malaysia (the "East Malaysia" region) and the Kingdom of Brunei to the north, with a high mountain-range dividing the center of the island. West Kalimantan became an autonomous Province in 1957, with its capital being the port-city of Pontianak.
Portuguese reconnaissance reports from the 1600s name Lawei and Tanjungpura as the regions within Borneo that were primary sources for diamonds, but these names are no longer used, and have vanished from any record. During this period, the mountainous central portion of the island was controlled by aboriginal Dayak headhunters. During the 18th century, the Dutch produced approximately 50,000 carats of rough Borneo diamonds annually.
Antique Borneo Map (c. 1700s) |
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Borneo's Kapuas River (Photo: Public Domain) |
Borneo's "Landak diamonds" were found by small-scale artisanal miners who sifted through river-bank alluvial deposits in the southern and western part of the island. Landak's diamonds most likely came from the Landak river, and Kapuas river, both terminating near the coastal city of Pontianak. Secondary sources were from the river-delta area around the coastal city of Banjarmasin. These rivers and their tributaries flowed from the volcanic (diamondiferous) mountainous region at the center of the island.
Borneo's Geology
Borneo is the third largest island in the world, after New Guinea and Greenland. Landak diamonds found on the island of Borneo, were created by the same geological forces that created the Himalayan Mountain range, and the "Ring of Fire" volcanic belt throughout Indonesia and the Pacific Rim. At the glacial rate of 10 centimetres per year, the Tethys Oceanic Crust collided, and subducted under the Asian Continental Plate, and the force of the collision caused volcanic activity which created the diamondiferous (diamond-bearing) intrusive and extrusive igneous rock known as kimberlite.
Kalimantan Barat (Photo: Public Domain) |
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NASA Satellite Photo of Borneo |
Millions of years of erosion caused by rainfall, unearthed the diamonds from their kimberlite source, and washed them downstream to their final resting place in the alluvial river gravels of the Landak/Kapuas drainage basin, and the Banjarmasin drainage basin to the southeast. No primary kimberlite or lamproite bodies have ever been located on Borneo, most likely due to the significant erosion that had taken place over the last several million years. Consequently, all diamond production on the island was limited to alluvial secondary deposits.
West Kalimantan - Landak Diamonds
Diamonds in this region of Borneo were found in the Ngabang area of West Kalimantan. The Gunung Niyut (Niyut Mountain 1,701m) in western Kalimantan Barat province (below, left) was the likely source for the eroded diamond-bearing material that fed the Landak river. To the immediate south of Landak, the Kapuas River (known as the "Mississippi of Borneo") is fed by rainfall from the Gunung Lawit and Pegunungan MŸller (2,240m) mountain ranges.
South Kalimantan - Cempaka Diamonds
South Kalimantan province is known as the "Land of a Thousand Rivers." Rainfall in the Pegunungan Meratus mountain range (1892m) in the south-eastern portion of the province (above, right) feeds into a massive drainage basin containing Riam Kanan Lake, and the Barito, Murung, and Negara rivers - all emptying into the sea at the Banjarmasin delta.
Borneo Map from 1800s
Small-scale artisanal mining continues to this day in South Kalimantan (Tengah Province), although Borneo is no longer considered a significant source for diamonds. The primary diamond-producing areas in this region are to the west of Riam Kanan Lake in the south, and the Upper Barito, Sungai Lahung, and Gula areas in Central Kalimantan. The Tengah Province capital of Martapura is known as the "City of Diamonds."
The villages of Lukaas and Sungai Tiung in Cempaka (southeast of the Banjarmasin delta) are a primary source for diamonds in South Kalimantan. Indigenous artisanal miners in this region still dig for diamonds, which are found in gravels and muddy sediments at a depth of around 10 meters. The men dig in groups of 10 to 20 people, using baskets to bring up the slurry. When a pit is dug to the correct depth, horizontal tunnels are then dug in a concentric circle.
Cempaka Miners (Photos: Lovelos, pbase.com)
Once excavated, the mud slurry is poured into conical wooden bowls which are swirled around, so that the lighter material collects towards the outer edge, while the heavier diamonds collect at the bottom.
South Kalimantan diamonds are classified as "black diamonds," "colorless" which are rare, "petrous" which are lower-quality yellow diamonds, and "pink diamonds" which can have a high brilliance.
In 1965, a 166 carat pink diamond known as the "Trisakti Diamond," was found in the Cempaka region. The Indonesian Government had the rough stone cut by Joseph Isaac Asscher in Amsterdam, the same year the same year it was found.
Bibliography on Borneo's Landak & Cempaka Diamonds
1. Goarchi, South Kalimantan - The Land of a Thousand Rivers  . www.goarchi.com
2. Muséum national d'Histoire naturelle France, Golconda Diamonds - The Dorjes . www.mnhn.fr
3. National Geographic, Diamonds: The Real Story
4. Janine Roberts, Glitter & Greed: The Secret World of the Diamond Cartel . The Disinformation Co.
5. Edward Jay Epstein, The Diamond Invention . www.edwardjayepstein.com
6. George E. Harlow, The Nature of Diamonds . Cambridge University Press
7. Fred Cuellar, How To Buy A Diamond 5th Edition . Sourcebooks Casablanca
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