Ahlfeld (1966, Fig. 10) on his sketch map shows this occurrence to consist of two intrusions, the larger southern one being an easterly-dipping sheet extending north-south over 4 km. There is an extensive contact aureole, particularly on the eastern side, with veining and brecciation. Of four described samples one consists of 50% fresh nepheline, 20% brown amphibole, a little diopside and arfvedsonite and no feldspar. Another specimen is a 'foyaite' with 15% albite-oligoclase, 20% orthoclase, 10% nepheline, 5% sodalite, about 20% olivine, diopside and biotite. Another nepheline syenite is described as containing abundant melanocratic veins and 10% riebeckite. A boulder was found of diopsideite with about 10% chrome diopside.
AHLFELD, F. 1966. Geologische Untersuchungen in der Provinz Ayopaya (Bolivien). Neues Jahrbuch fur Mineralogie, 104, 147-71