The Senakin mine, South Kalimantan, operated by PT Arutmin Indonesia mines Eocene age coal. This economically important coal occurs near the base of the T2 member of the Tanjung Formation The laterally continuous basal coal unit is up to 9 m thick, but is more typically 4 to 6 m.

The lower part of the Eocene seam is low in sulfur, whereas the upper part has higher levels due to increased pyrite content or subsequent sulfate alteration. The coal bed varies vertically in ash and sulfur content but this variation is laterally consistent and predictable.

Arutmin manages 6 open cut coal mines: Senakin, Satui, Mulia / Jumbang, Sarongga, Asam-Asam, and Kintap. All mines are strategically located near Arutmin’s port facilities - the North Pulau Laut Coal Terminal (NPLCT) which is located on the north coast of Pulau Laut.

The Senakin mine produces bituminous coal. The process includes breaking the coal chunks into smaller pieces, separating them by the desired sizes, and cleansing them to reduce ash content and increase selling price.