Vesicular volcanic ejecta, essentially magma that has been frothed up by escaping gases. It is a textural variant of pumice, with scoria typically being less vesicular, denser, and usually very bubbly (vesicular) basalt or andesite. Both scoria and pumice develop their bubbly textures when escaping gas is trapped as lava solidifies. Scoria is more dense and darker than pumice.
The Albuquerque Volcanoes are each a scoria cone or cinder cone as opposed to a caldera.