Red Tuff with reduction spots
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Fact sheet

Red Tuff with reduction spots

This sample is a volcanic tuff from The Sisters, a small volcanic plug near the town of North Berwick, East Lothian, Scotland.  The tuff is Carboniferous in age, appears red in the field, and underlies basaltic lava flows. A sequence of these rocks is well exposed on the shoreline at low tide. The backdrop to the location is North Berwick Law, a phonolitic trachyte plug which reaches a height of 613ft (187 m). Off shore is another phonolite plug - Bass Rock – famous for its gannet colony.

The thin section reveals banding on a small scale with grading of the clasts and fragments, which appears to indicate that the tuff is at least partially reworked and water lain. It is perhaps better regarded as a volcaniclastic sediment. The thin section contains one large clast of altered glass over 5 mm in length, and several others glass rich clasts on the left hand side of the section. The remainder of the section is composed of angular fragments of quartz, feldspar and glass-rich rock fragments in bands in an altered matrix. The fragment grain sizes in different bands range from tens to hundreds of microns.

Additional images
  • close up of the hand specimen
  • Polished surface of the hand specimen
  • Hand specimen of the Tuff
56.0603, -2.7146
The Sisters, near North Berwick, East Lothian, Scotland
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

Rock-forming mineral
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: