An oval intrusion of about 9x5 km, Cachorro is elongated northwest-southeast, with a smaller intrusion of about 4 km diameter to the south-southeast. It consists of quartz syenite with an amphibole and biotite, but it is not clear if the intrusions are peralkaline.
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Mutum is an approximately circular intrusion of 16 km2, part of which lies in Guyana, emplaced in basement rocks of the Guyana shield.
This is a nearly circular intrusion some 2 km in diameter which is classified as part of the Uatuma Group igneous cycle (1900-1400 Ma).
Maicuru forms a circular hill within rocks of the Guyana Shield and is capped with lateritic deposits. On morphological and structural grounds it is considered to be an ultrabasic alkaline intrusion, probably with associated carbonatite.
Apupariu consists of three intrusions which have been identified by radar imagery, and interpreted as alkaline by comparison with known intrusions in the area, but they have not been sampled.
Maraconai comprises two oval-shaped intrusions emplaced in metamorphic rocks of the Vila Nova Group, the larger of some 25 km2, the smaller about 8 km2. Both intrusions are deeply weathered to laterite which shows high anomalies for Zr, Ni, Cr, V and Ta.
Outcrops of nepheline syenite gneiss occur at three localities in the vicinity of Boca Nova, but airborne gamma-spectrometric surveys indicate the probable presence of an extensive body.