The islet is a steep conical volcanic structure starting from the bottom of the sea at 600m depth, ascending to a top 125 meters above the sea level.

Its subaerial part consists of flows of andesitic hypocrystalline porphyritic lava.

Phenocrysts are:

plagioclase, clinopyroxene, orthopyroxene and magnetite.

Microliths of plagioclase, clinopyroxene and magnetite are observed in the abundant vitreous mass.