Alkaline Rocks and Carbonatites of the World

Setup during HiTech AlkCarb: an online database of alkaline rock and carbonatite occurrences

Cerro San Cristobal

stripes

Occurrence number: 
022-00-001
Country: 
Bolivia
Region: 
Cochabamba
Location: 
Longitude: -66.97, Latitude: -16.97
Carbonatite: 
No

This intrusion of about 1.2x0.4 km has a narrow, hornfelsed aureole 15-20 m wide. One rock type consists of 70% nepheline, which is slightly replaced by cancrinite, a little orthoclase and albite, and sparse biotite and sodic amphibole; femics constitute less than 10% of the rock. In boulders derived from the intrusion sodalite has been identified. Numerous boulders of coarse, white calcite rock also occur which contain nests of apatite crystals and an unidentified Zr-Ti silicate. The difficulty of the terrain has, so far, precluded a detailed investigation of the occurrence.

References: 
AHLFELD, F. 1966. Geologische Untersuchungen in der Provinz Ayopaya (Bolivien). Neues Jahrbuch fur Mineralogie, 104, 147-71
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith