Darwin wrote "Calcareous sandstone, concretions in above (referring to 2114-2116) - Pale brown indurated earthy stone with white fragments, forming a breccia".
This fragmental rock consists of rock, mineral and glassy material which was produced when basaltic lava interacted with sea-water during eruption. Palagonite is the alteration product of glassy basalt which in places is tinted yellow, suggesting later weathering. Sample Location: Chiloe Island, Chile. Collected June-July 1834.
This collection was a collaboration between The Open University and the Sedgwick Museum, created in 2009 to celebrate the bicentennial of the birth of Charles Darwin.
The Sedgwick Museum opened a new gallery, 'Darwin the Geologist', and created a museum-based virtual microscope to showcase rocks he collected during the Voyage of the Beagle. We enjoy this collection because Darwin did not always pick up a representative sample from the islands he visited; it's often the unusual rocks that caught his eye. Just explore the collection and you'll see what we mean. For those who have the opportunity, a visit to the museum is strongly recommended.