Vesicular basalt - Isle of Mull
Collection:
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Microscope
Click the microscope button to view a thin section for this sample.
Microscope

Fact sheet

Vesicular basalt - Isle of Mull

This vesicular basalt comes from Creag Brimishgan on the Isle of Mull, Inner Hebrides, Scotland. It was erupted during the Paleogene igneous province that erupted in a short time period across Scotland, northern England, Northern Ireland and Greenland. The rock was subjected to low-grade metamorphism and fluid ingress as later lavas covered this one, and the cavities (vesicles) that originally formed as gas bubbles in the lava were filled with secondary minerals such as the zeolite mineral pumpellyite.

In thin section the rock is a coarse grained basalt, with a framework of plagioclase laths 1-3 mm long that have been extensively altered to clays. Pyroxene is much less altered and exhibits a poikillitic texture (a large grain containing smaller grains of another species). Vesicles appear angular rather than spherical and are filled by fine-grained pumpellyite lining the cavities and forming delicate rosettes of needle-shaped crystals.

Map
56.496049, -6.025314
Description:
Creag Brimishgan, Isle of Mull, Scotland
Precision:
Moderate
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
metamorphic
Category
basalt
Rock-forming mineral
pyroxene
olivine
pumpellyite
plagioclase
feldspar
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: