Lucas Lanzoni · CC BY-SA 4.0Cerro Ñemby (tapón volcánico de nefelinita)
A truncated cone of volcanic rock in the middle of Ñemby: the remains of a magma conduit that erosion left exposed.
What it is
Cerro Ñemby is a volcanic plug: what remains of the conduit through which magma rose, hardened and later freed by the erosion of the softer rock around it. It is made of nephelinite, a silica-poor volcanic rock of the Asunción Alkaline Province, with columnar structures. Inside it geologists found mantle xenoliths (olivine peridotite fragments, mostly lherzolites), chunks of rock from tens of kilometres down that the magma carried to the surface.
It has a truncated-cone shape, about 700 metres across at its base, and belongs to the chain of low hills known as the Ybytypanemá, which runs from Villarrica to Asunción. It was quarried for more than 50 years; it was later expropriated and transferred to the municipality of Ñemby by decree. The UNA study highlights its educational value.
How to visit
It sits inside the city of Ñemby, a few kilometres from Asunción. Ask the municipality about access conditions, since it is a former quarry.
Nearby
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Cerro Ñemby y su laguna esmeralda
An extinct volcano some 45 million years old, turned by a quarry into a green-water lagoon.
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Villa Elisa
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Researched and reviewed in September 2026 with 4 sources. A second reviewer checked dates, coordinates and lodging. Hours and prices may change.