The Calenturitas coal deposit is part of Tertiary coal-bearing sediments preserved in the Cesar-Rancheria Basin. This basin is limited tectonically by the Oca Fault in the north and the Bucaramanga-Santa Marta Fault in the south and west. Two other structural settings control the basin limits, the igneous and metamorphic complex of Sierra Nevada de Santa Marta to the north and the Serrania de Perija to the southeast. These mountain ranges are an extension of Colombia’s Eastern Cordillera.

The Calenturitas coal deposit occurs within a northeast-trending asymmetrical syncline, the axis of which plunges at less than 10º towards the southwest. Seams dip at 5º to 10º on the northeastern nose of the syncline. Seam dips increase along the limbs of the syncline to 18º along the eastern limb and up to 55º on the western limb. Coal seams are relatively flat-lying in the vicinity of the synclinal axis with dips less than 10º observed on seismic lines crossing the area.

The Calenturitas coal deposit can be characterised as a deep, multiple seam, sub-cropping and steep to moderately dipping synclinal basin. The dipping nature of the coal structure makes it suitable for excavation using conventional open cut mining methods that initially excavate low strip ratio sub-cropping coal followed by deeper coal mining that progresses from one end of the deposit to the other.

A combinatation of small and large hydraulic excavators (100 t - 550 t) are used to load overburden into off highway rear dump trucks which haul the material to a combination of inpit and expit dumps.

Coal mining is by a combination of hydraulic excavators working in tandem with dozers. Medium sized backhoes excavate the overburden and interburden to near the contacts between waste and coal. Smaller dozers or flat bladed small hydraulic excavators clean the waste materials from the coal roof contact. The care taken in this method determines the amount of both loss and dilution. Finally, excavators dig the waste material which has been heaped by the dozers.

Coal is hauled to the ROM pad located at the current coal handling facility.

Calenturitas coal is not washed; there is no wash plant for either Calenturitas or La Jagua coal. ROM coal is sized and sold as product coal.

There are stockpiles at the mine to facilitate blending and to smooth fluctuations in coal supply due to weather and interruptions to the continuity of coal supply due to equipment maintenance and other interruptions.

There are variations in coal quality between each seam and between each pit. Blending is achieved by:
- mining from different pits during the one shift;
- mining from different seams;
- blending at the crusher;
- blending on the stockpile before the train is loaded; and
- further blending at the port(s).