Brisbane tuff is a type of rock, formed as a result of a volcanic eruption. As the name suggests, it is a type of tuff found in Brisbane, Queensland, Australia. It is a form of welded ignimbrite. Brisbane tuff comes in a variety of colours: pink, green, blue (grey) and purple. The different colours are due to the extent of oxidation of iron and manganese. It is often incorrectly described as porphyry.