Alkaline Rocks and Carbonatites of the World

Funded by HiTech AlkCarb - New geomodels to explore deeper for Hi-Tech critical raw materials in Alkaline rocks and Carbonatites

Monjolos

stripes

Occurrence number: 
025-00-079
Country: 
Brazil
Region: 
Rio de Janeiro
Location: 
Longitude: -42.93, Latitude: -22.82

A small plug of porphyritic phonolite cuts Tertiary sediments of the Barreiras Formation. Phenocrysts of feldspar, aegirine, nepheline and mica occur and analcime is present in amygdales.

References: 
LIMA, P.R.A. dos S. 1976. Geologia dos macicos alcalinos do estado do Rio de Janeiro. Semana de Estudos Geologicos, Itaguai: 205-59
Fig. 204 Distribution of alkaline rocks around Rio de Janeiro.
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith