This sample of porphyritic rhyodacite, comes from Beinn nan Stac on the Isle of Rum. It forms part of a complex of intrusive sheets and ignimbrites in teh Southern Mountains Zone of southeastern Rum. This sample contains banding and welded fiamme indicating a pyroclastic eruption.
The thin section consists of plagioclase, quartz and small hornblende phenocrysts. Crystal fragments are visible in a fine grained matrix in which attenuated fiamme give an impression of flow banding. Relic shards and vesicles can also be seen.
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.