Phonolite pumice (24-25 August 79 A.D. eruption of Mt. Vesuvius, east of Naples, Campania, Italy)

Mt. Vesuvius is the most famous volcano in Europe. It has erupted on a semi-regular basis over the last 2000 years. Vesuvius is a ~300,000 year old subduction zone stratovolcano located just east of the major Italian city of Naples, coastal Campania, southern Italy.

The most famous Vesuvius eruption occurred on 24-25 August, 79 A.D. An enormous ash eruption and collapsing ash column destroyed and buried three Roman towns (Pompeii, Herculaneum, and Stabiae). A written eyewitness account of the eruption has survived. Pompeii has been extensively excavated by archaeologists since its discovery in the mid-1700s. It is widely considered to be the most significant archaeological site on Earth. Pompeii is rarely mentioned in ancient historical records, but historians & archaeologists understand Pompeii better than Rome itself in many ways. The most famous Pompeii discoveries are casts of people (& animals) preserved in the volcanic deposits. The casts are empty spaces in the ash & pumice. They have been filled with plaster & the matrix subsequently removed. Expressions of pain & anguish can still be seen preserved on some of the Romans’ faces.

The rocks shown above are phonolite pumice from the late August 79 A.D. eruption that buried Pompeii. This eruption produced ash and pumice having phonolite and tephriphonolite compositions (= alkaline, intermediate, extrusive igneous rocks).