Arenite sandstone - Falkland Islands
Click the microscope button to view a thin section for this sample.
Click the microscope button to view a thin section for this sample.

Fact sheet

Arenite sandstone - Falkland Islands

Darwin wrote: "True granular quartz rock, with little interstitial powder"

This Silurian-Devonian sandstone consists of angular to sub-rounded quartz grains cemented by a brown micaceous infill. Collected Mar-Apr 1834.

Additional images
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-51.721667, -61.300278
New Island, Falklands Islands
About this collection

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.

Darwin collected some 2000 rock specimens on the voyage, under difficult conditions exacerbated by 'perpetual' seasickness. These specimens were gifted to the Sedgwick Museum after Darwin's death by his executors. Thin sections were made from these hand specimens in the early years of the Twentieth Century by Alfred Harker, a pioneer of thin section petrology. He curated a collection of 42,000 rock specimens, as well as numerous thin sections, from the 1880s up to his death in 1939: these specimens form the core of what is now known as the Harker Collection. Harker published 'Notes on the rocks of the "Beagle" Collection' in the Geological Magazine in 1907. He also made a handwritten copy of the catalogue (omitting the sedimentary rocks!); you can view the Contents list and a rationale for the catalogue on the Darwin Online site.

For those who have the opportunity, a visit to the museum is strongly recommended. See the Sedgwick Museum website for more information.

Sample details

Rock-forming mineral
Category guide  
Category Guide
Refers to any word or phrase that appears in the individual rock names. Names are generally descriptive; they allow users to search for broad terms like ‘granite’ as well as more specific names such as ‘breccia’. However, the adjacent descriptions of the specimens captures a wider range of general words and phrases and is a more powerful search tool.
Refers to any word or phrase that appears anywhere in the descriptions of the specimens
Accessory minerals
Minerals that occur in very low abundance in a rock. They are usually not visible with the naked eye and contribute perhapssver, they often dominate the rare elements such as platinum group metals.
Rock-forming minerals
Minerals that make up the bulk of all rock samples and are also the ones used in rock classi?cation.
Selecting one or more period, for example 'Jurassic'.
A term used to group together related samples that are not already gathered into a single Collection. For instance, there is a ‘SW England granites’ theme that includes such rock types as granite, hydrothermal breccia, skarn and vein samples.
A general term used to label a rock sample. It is a useful way of grouping similar samples throughout a collection. Category names are often, but not exclusively, common rock names (e.g. granite, basalt, dolerite, gabbro, greisen, skarn, gneiss, amphibolite, limestone, sandstone).
The owner of the sample that appears in the collection. For example, NASA owns all the samples that appear in the Moon Rocks collection
We would like to thank the following for the use of this sample: