Sebuku (old spelling Seboekoe) is a island south-east of

Borneo Borneo () is the List of islands by area, third-largest island in the world, with an area of , and population of 23,053,723 (2020 national censuses). Situated at the geographic centre of Maritime Southeast Asia, it is one of the Greater Sunda ...

and administratively part of

South Kalimantan South Kalimantan () is a Provinces of Indonesia, province of Indonesia. It is the second most populous province on the island of Kalimantan, the Indonesian territory of the island of Borneo after West Kalimantan. The provincial capital was Banjar ...

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania, between the Indian Ocean, Indian and Pacific Ocean, Pacific oceans. Comprising over List of islands of Indonesia, 17,000 islands, including Sumatra, ...

. Sebuku is home to a large

coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other Chemical element, elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal i ...

mine operated by Straits Asia Resources, which produces 3 million tonnes of coal every year.

Overview

Sebuku is located to the south-east of Borneo, approximately from

Laut Island Laut ('' Luh-OOt''; ) is an island located in northern Java Sea, to the southwest of Makassar Strait. It is administratively part of the Kota Baru Regency in the Indonesian province of South Kalimantan South Kalimantan () is a Provinces of In ...

. It is roughly from north to south and from east to west at its widest point, covering a total area of . Administratively, it is part of

. It is on the Kanibungan Fault. Coal was first found on the island by the Dutch colonial government in 1925. Large deposits of coal, dating from the

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

, have been found in Sebuku's south-west region; the main deposit forms a

syncline In structural geology, a syncline is a fold with younger layers closer to the center of the structure, whereas an anticline is the inverse of a syncline. A synclinorium (plural synclinoriums or synclinoria) is a large syncline with superimposed ...

which trends from north to south. The

strata In geology and related fields, a stratum (: strata) is a layer of Rock (geology), rock or sediment characterized by certain Lithology, lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by v ...

around the coal is mainly

mudstone Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from ''shale'' by its lack of fissility.Blatt, H., and R.J. Tracy, 1996, ''Petrology.'' New York, New York, ...

and

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of Clay mineral, clay minerals (hydrous aluminium phyllosilicates, e.g., Kaolinite, kaolin, aluminium, Al2Silicon, Si2Oxygen, O5(hydroxide, OH)4) and tiny f ...

. Sebuku is home to roughly 4,900 people, with a total population density of . Prior to the opening of the coal mine, it had no infrastructure; now there are small roads, a port, and a small airfield.

Mining

Although the Dutch originally discovered at least 25 coal deposits on Sebuku, after realizing that the island may not survive mining they cancelled their plans. Instead, they kept the island as a preserved park to serve as a buffer for Laut Island. Due to estimates of coal reserves measuring eleven million metric tonnes, infrastructure for a mine was built beginning in June 1997; mining began in December of the same year, despite concerns that the mining could sink the island. The mine is operated by

Singapore Singapore, officially the Republic of Singapore, is an island country and city-state in Southeast Asia. The country's territory comprises one main island, 63 satellite islands and islets, and one outlying islet. It is about one degree ...

-based Straits Asia Resources, a subsidiary of Straits Resources. Mining is done using multiple open pits. As of 30 June 2008, the total remaining coal was estimated at 384 megatonnes, with a reserve base of 19 megatonnes. Production is estimated to be 3 megatonnes per annum.

References

{{reflist Coal mines in Indonesia Islands of Kalimantan Landforms of South Kalimantan Populated places in Indonesia