Syenite - Ben Loyal
Collection:
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Object

Fact sheet

Syenite - Ben Loyal

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
  • syenite - width 1.8cm
  • syenite - width 1.8cm
Map
58.375775, -4.380176
Description:
Cnoc nan Cùilean, Ben Loyal, NW Scotland
Precision:
Good
About this collection

The United Kingdom Virtual Microscope (UKVM) collection consists of igneous, sedimentary and metamorphic rocks from around the UK.

It is intended as a teaching resource, helping to tell the story of the common rock types and how they form, and reflecting the history of the UK at the margins of the continent of Europe. The collection is a series of teaching sets, for example igneous rocks from the North Atlantic Igneous Province and SW England; high-temperature metamorphic rocks from Scotland and low-temperature metamorphic rocks from Wales; and sedimentary rocks, including English limestones and sandstones.

Sample details

Type
igneous
Category
syenite
Rock-forming mineral
pyroxene
aegirine
arfvedsonite
amphibole
orthoclase
feldspar
Accessory minerals
titanite
actinolite
allanite
fluorapatite
ilmenite
magnetite
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: