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Fact sheet


Uraninite (uranium oxide) is the main ore mineral of the radioactive element uranium, one of the more unusual metals produced in Cornwall. Uraninite occurs in very small amounts in the region’s granites and in associated veins. This specimen comes from South Terras Mine, near Grampound.

South Terras was originally an iron mine but uraninite was found there in the 1880s. A new mining company was formed and by 1890, 33 people were employed. Most of the ore was shipped to Germany for use in the coloured-glassmaking industry. 

Marie Curie’s discovery of the element radium switched interest in South Terras Mine away from uranium. Early research suggested radium had profound health-giving properties and its value soared.  In 1909 it was one of the most expensive substances in the world. In 1912 a new French company was registered to operate South Terras. One of Marie Curie’s colleagues, Dr. Marcel Pochon, superintended operations at the mine. It finally closed for the last time in the early 1930s.

Chemical Formula: UO2

Specimen no. TRURI: 1979.17.36
Location: South Terras, St Stephen-in-Brannel
Grid Reference: SW 935 924


Additional images
  • Uraninite 9 cm across
  • Uraninite 12 cm across
50.334888, -4.904666
About this collection

This Collection focuses on Cornwall and West Devon’s mineralogical and mining heritage.  The specimens it features are drawn from the collection of the Royal Institution of Cornwall (RIC) held at the Royal Cornwall Museum (RCM). 

This collaborative project involving the RCM, the Cornish Mining World Heritage Site and The Open University explores how access to the RIC’s mineral collection and the stories it can tell can be widened using digital technology.  It includes radioactive minerals from Cornwall that would otherwise be inaccessible to the public for health and safety reasons.

Sample details

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: