UK: Syenite
Collection:
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Fact sheet

UK: Syenite

The Ben Loyal syenite intrusion is one of the largest areas of alkaline igneous rocks in Britain. It was intruded around 426 million years ago after the peak of Caledonian metamorphism in rocks of the Moine and Lewisian groups in the Highland of Scotland. Intrusion of the syenite is thought to have been guided by deformed and folded country rocks to form the current body. This sample comes from the Cnoc nan Cùilean intrusion, a satellite body to the main intrusion, now separated from the main intrusion by the Loch Loyal fault, and is thought to have intruded as a series of sheets.

In thin section the most obvious constituents are green pyroxene (aegirine-augite) and colourless, cloudy orthoclase feldspar. The cloudiness is caused by exsolution of plagioclase feldspar from the orthoclase as the crystals cooled and re-equilibrated. Well-formed (euhedral) crystals of titanite are relatively common, and elsewhere in the sample accessory amounts of actinolite, allanite-(Ce), fluorapatite, ilmenite, magnetite and zircon also occur.

Additional images
Map
58.375909, -4.37994
Description:
Cnoc nan Cùilean, Ben Loyal, NW Scotland
About this collection

The Ilimaussaq alkaline complex is the type locality for agpaitic nepheline syenites and represents an enormous concentration of rare elements, notably Li, Be, Nb, Zr, REE, Y, Th and U. Around 220 mineral species have been identified. We can't identify all the minerals present in these samples. Email us at virtual-microscope@open.ac.uk if you can help.

Note we have recently expanded the collection to include other syenite complexes worldwide.

See also Alex Strekeisen's great website for more information on syenite complexes.

Sample details

Collection: Greenland
Type
igneous
Rock-forming mineral
aegirine-augite
arfvedsonite
orthoclase
Accessory minerals
titanite
allanite
ilmenite
fluorapatite
zircon
Category guide  
Category Guide
Title
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.
Description
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.
Timescale
Selecting one or more period, for example 'Jurassic'.
Theme
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.
Category
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).
Owner
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: