Basalt with xenolith – North Berwick
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Fact sheet

Basalt with xenolith – North Berwick

This plagioclase-phyric basalt with xenoliths was collected near  the Harbour, in the town of North Berwick, although the lava flow from which it comes, the Dunsapie basalt, is named after a crag and small loch on Arthurs Seat in Edinburgh. The sample is Carboniferous in age, and was one of a suite of volcanic eruptions in the Scottish borders at this time.

In thin section the plagioclase phenocrysts appear altered, particularly along cracks. Large almost circular amygdales (vesicles filled with secondary minerals) appear to be filled with very fine grained material, possibly zeolites which form a lining of fibres radiating inwards and an inner zone of random orientations with some rosettes of radiating crystals. Other amygdales contain radiating bundles of coarser grained zeolite crystals. A large xenolith of a banded rock occupies about a quarter of the thin section. The xenolith may have been derived from the local sediments and tuffs but the minerals of the xenolith are altered so it is difficult to be certain of its origin.

Additional images
  • Hand specimen showing xenolith
  • Hand specimen of basalt
  • Close up of basalt and xenolith
56.0612, -2.7162
Close to the Scottish Seabird Centre, The Harbour, North Berwick
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

Accessory minerals
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: