Achnaba Green Schist Setts and Paving Stone

Achnaba Stone is immensely old, with an origin some 600 million years ago making it one of Scotland’s oldest exposed rocks. Volcanic in origin, this rock started as a basalt or dolerite, the same type of rock commonly associated with the Isles of Mull and Staffa, and most famously in Northern Ireland at the Giants Causeway. Where this stone differs from ‘common’ basalt is as a result of subsequent metamorphism; it has been subjected to high pressures and temperatures during a geological process known as the Caledonian Orogeny around 400 million years ago, when the great mountain ranges of northern Europe were being formed, and this material had been deeply buried.