P. J. J. Jansen

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tagsperson, geologist, dutch, colonial
aliasesP. J. J. JANSEN, Jansen, Jansen (geologist)

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P. J. J. Jansen was a Dutch mining engineer who, together with his colleagues Lindberg and Wolvekamp, conducted in 1922 the most systematic colonial-era exploration for primary and secondary gold deposits in the Residency of Atjeh, and whose joint report — cited in the standard scholarly form “JANSEN, LINDBERG and WOLVEKAMP, 1922” — is the principal source for Van Bemmelen’s *Geology of Indonesia* (1949) in its treatment of Atjeh gold, iron-ore, and copper occurrences. The report’s page-references (pp. 131–132, 141, 151, 152, 153) recur throughout Van Bemmelen’s catalogue of Atjeh mineral localities, and the assay figures it records for the quartz-veins of the S. Assai and S. Meranging remain the only printed primary-gold assays for Atjeh.

The 1922 Atjeh exploration

The Jansen-Lindberg-Wolvekamp exploration of Atjeh was the most ambitious single mineralogical survey of the residency undertaken during the colonial period. Its scope, as recoverable from Van Bemmelen’s citations, covered at least four classes of occurrence:

  1. Primary gold deposits. From 35 samples taken from quartz-veins in the pre-tertiary slate-formation of the Atjeh interior, only two yielded good assays: one from the river basin of the S. Assai (11 gr Au/ton) and one from the S. Meranging (10.8 gr Au/ton). The report accordingly recommended “the upper-Assai region… for a more detailed investigation”.

  2. Iron-ore deposits. The report supplies the canonical list of Atjeh iron-ore localities: Kr. Geuenteuet (32 km South of Kota Radja), Gle Mon Ampeuet (37 km South of Kota Radja), Kr. Ligan (Babah Loh) (113 km NW of Meulaboh), Kr. Rigaih (88 km NW of Meulaboh), Alu Talu (78 km NW of Meulaboh), Kwala Boe and Tjot Plaj (30 and 12 km NW of Meulaboh), A. Pentuwa Gade (68 km SE of Meulaboh), and Kuto Buloh (27 km North of Tapa Tuan). For each locality Jansen, Lindberg and Wolvekamp recorded the geological context — contact-metamorphic magnetite-hematite deposits at the boundary of eruptive rocks (diorite, amphibole-andesite) and limestones, with garnet and silicified limestone as diagnostic minerals — and at Kr. Geuenteuet they noted “much pyrite and large boulders of magnetite containing a core of pyrite” with an analysis of “10 gr Au and 33 gr Ag per ton”.

  3. Bog-iron and swamp-ore deposits. At the localities of Tjot Plaj and Kwala Boe, Jansen-Lindberg-Wolvekamp recorded scattered fragments of bog-iron ore at the surface, with reddish-yellow sand below 40 cm containing lumps of ore; their rough estimate gave “only 10–15 % of ore-fragments… in these 40 cm” and a total of “300,000–400,000 tons of lump-ore” across an area of about 2 sq km.

  4. Copper occurrences. The report is also cited, in the copper chapter of Van Bemmelen, for the Atjeh copper localities (Pulu Bras, Gle Broë, Aer Talu, Beutong, Aloe Baru, Aer Si Hajo, Muara Sipongi).

Method

The 1922 report appears, from the pattern of Van Bemmelen’s citations, to have been a structured mineralogical survey conducted on behalf of the Netherlands Indies Geological Survey or the Bureau of Mines in Indonesia, in which the three engineers visited the known Atjeh mineral occurrences, sampled them, recorded their geological setting and approximate reserves, and submitted a consolidated report. The names of the three authors are uniformly cited together, suggesting a joint field-party; and the page-references Van Bemmelen gives (pp. 131–153) indicate a single report of substantial length. The report’s tonnage and assay figures are reproduced by Van Bemmelen without correction, which suggests that the colonial mining service regarded them as the best available data on Atjeh mineralogy at the date of publication of The Geology of Indonesia in 1949.

Significance

The Jansen-Lindberg-Wolvekamp report is significant for the encyclopedia of Acheh history on two grounds. First, it is the only systematic colonial-era survey of Atjeh’s primary gold potential, and the S. Assai and S. Meranging assays it records are the only published primary-gold assays for Atjeh from the colonial period. Second, it is the canonical source for the inventory of Atjeh iron-ore localities, and the 1920 reserve figure of 2,600,000 tons of 58–64 % Fe ore at Kr. Geuenteuet which Van Bemmelen reproduces derives ultimately from the Jansen-Lindberg-Wolvekamp field-work. Any modern study of the historical mineralogy of Atjeh must therefore begin with their 1922 report.

See Also

Source

The Geology of Indonesia, by R. W. van Bemmelen, Vol. II: Economic Geology (The Hague: Government Printing Office; Martinus Nijhoff, 1949), pp. 121–122 (Atjeh gold), pp. 205–211 (iron ores in Sumatra), p. 147 (copper in Sumatra). The Jansen-Lindberg-Wolvekamp report itself is cited throughout as: “P. J. J. JANSEN, B. B. LINDBERG and H. WOLVEKAMP. 1922”.

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