Cinder cones are composed of basalt. The properties of basalt and the gasses that are contained within allow cinder cones to be created with their unique morphologies. Some cinder cones have unique lava flow styles due to their structure. Cinder cones are composed of erupted pyroclastic debris called "cinders". There are many spaces between the erupted cinders that form the slopes of a cinder cone, and this allows low viscosity basalt to flow out from the base of the cone. Below: Dotsero's basalt lava flow.
Colorado Geological Survey