Andesite igneous rock specimens of late Ordovician age which form part of the Barrowdale volcanic group. The rocks come from Cumbria, UK and have a dark colouration with a blue tint and may contain augite crystals. The rocks are intermediate in chemistry and suitable for higher level education to explain the difference in various igneous groups. Samples are available in 3 sizes and will come supplied in a card tray with an information label.