Darwin wrote "Greenstone with mica (& quartz veins) forming mass of hill, cutting through & overlying slate (fine crystals of hornblende; many scales of mica; crystals of albite but two macles; numerous specks of pyrites; heavy compact rock, coarsely crystallized"
Euhedral crystals of green amphibole dominate this well crystallized diorite. Large, zoned crystals of plagioclase feldspar interstitial quartz and accessory amounts of opaque iron oxides (ilmenite?) complete the assemblage. Collected Apr-Jun 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.