This is a small occurrence of syenite which contains aegirine-augite and is surrounded by Quaternary sediments.
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Rio Grande do Sul
This is a province of over 30 pipes, up to 500 metres in diameter, which extends over a northwest-trending area of 20x5 km along the Arroio Moirao Graben. Most of the pipes intrude red beds of the Caneleiras Formation, are related to fractures and occur in clusters of two or more.
This is a dome approximately 6 km in diameter, similar to Vargeao (025-00-111), beneath which may lie an alkaline complex.