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Fact sheet


Chalcocite (copper sulphide) is an important ore mineral of copper.  It has more than double the copper content by weight % of chalcopyrite (the most common ore of copper) and is therefore a much more profitable ore mineral.  It was the main copper ore worked in the rich West Penwith mines of Geevor, Botallack and Levant. 

This specimen is from Geevor and was collected underground in 1964. It shows beautiful, almost hexagonal, tabular crystals intergrown with each other.

Geevor is better known as a tin mine, with underground workings that extended out under the sea. It was one of the last working mines in Cornwall, closing in 1990.

Chemical Formula: Cu2S

Specimen no. TRURI: 2005.42.1
Location: Geevor mine, Pendeen
Grid Reference: SW 375 345


Additional images
  • Chalcocite 4.5 cm across
  • Chalcocite 4 cm across
  • Chalcocite 3.5 cm across
50.152308, -5.676079
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.
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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: