Quensel (1912, p. 79) has described a group of rocks he called 'essexites', together with 'comenditic granophyres' and syenites from the vicinity of Cerra Cagual. The essexites are gabbroic rocks with orthoclase but no nepheline. However, syenites contain aegirine-augite. Little detail as to field relationships is available but chemical analyses are given. Essexites and monzonites are also described from Cerro Payne (Paine) to the south, but these also are devoid of nepheline.