Rocks from effusive volcanoes like Puy de la Vache are rather light rocks colored from dark gray to black and brick red to dark red. If they contain few visible crystals, or phenocrysts, they are pierced with numerous gas bubbles. The lava projected from Puy de la Vache formed solid elements of small size (slags, pumiceous lapilli, pozzolanas) or larger, elongated volcanic bombs. It also solidified into a 9.3 miles (15 km) long flow called cheire.