S. Assai (Sungei Assai, modern Sungai Assai) is a river of Atjeh whose quartz-veins yielded, in the 1922 survey of Jansen, Lindberg and Wolvekamp, the highest-grade gold assay of any Atjeh primary-gold occurrence recorded in the colonial geological literature: 11 gr Au/ton. The S. Assai locality is recorded in Van Bemmelen’s *Geology of Indonesia* (1949) in the Summary of the Explorations in Sumatra section of the gold-and-silver chapter, and the upper-Assai region is recommended by Van Bemmelen “for a more detailed investigation”.
The 1922 Jansen-Lindberg-Wolvekamp assay
Van Bemmelen’s record of the S. Assai assay reads:
“From 35 samples, taken from quartz-veins, only two gave a good assay: one from the river basin of the S. Assai, one from the S. Meranging (resp. 11 and 10.8 gr Au/ton). The upper-Assai region is recommended for a more detailed investigation.”
The 11 gr Au/ton assay is the highest of the two positive assays from the 35 quartz-vein samples taken by Jansen, Lindberg and Wolvekamp in the Atjeh interior in 1922. The fact that only 2 of the 35 samples yielded positive assays — and that those 2 assayed at near-identical grades (11 and 10.8 gr Au/ton) — suggests that the Atjeh primary-gold potential is concentrated in a small number of structurally-controlled quartz-vein systems rather than being disseminated across the slate-formation as a whole. The upper-Assai region’s recommendation “for a more detailed investigation” is the only positive prospecting recommendation for an Atjeh primary-gold occurrence in the colonial geological literature.
Significance
S. Assai is significant for the encyclopedia of Acheh history because it is the site of the highest-grade gold assay of any Atjeh primary-gold occurrence recorded in the colonial geological literature — 11 gr Au/ton from a quartz-vein in the slate-formation — and accordingly the most attractive primary-gold prospect recorded in the colonial geological literature on Atjeh. The upper-Assai region’s recommendation “for a more detailed investigation” is the only positive prospecting recommendation for an Atjeh primary-gold occurrence in the colonial geological literature, and it accordingly marks the S. Assai as the colonial geological service’s preferred target for any future primary-gold exploration in Atjeh.
See Also
- Acheh
- B. B. Lindberg
- Gold and silver in Atjeh
- H. Wolvekamp
- P. J. J. Jansen
- S. Meranging
- Van Bemmelen’s The Geology of Indonesia (1949)
- 1922
Source
The Geology of Indonesia, by R. W. van Bemmelen, Vol. II: Economic Geology (The Hague: Government Printing Office; Martinus Nijhoff, 1949), p. 122 (Summary of the Explorations in Sumatra, Atjeh primary deposits).