Cinder cones are compsed of rock fragments which have been ejected from a vent possibly as molten lava , cooled on their descent and dropped downwind of a volcanic vent. Often made of scoria and tephra ( small volcanic rock fragments) they from quickly perhaps over a few days. They can 100 of metres tall. The rock fragments are cooled quickly and glassy in texture. They require low viscosity lava to form such as basalt and can be found in Iceland and on Mt.Etna.