suevite

Suevite is a composite rock formed under extreme force and heat when a meteor impacts the earth. It is a breccia containing rock fragments and cooled impact-melt material, including glass. It is very similar to tuff in appearance and possesses similar utility.

The rock contains fragments of pre-existing rocks together with material melted during the impact and subsequently cooled. It is the resulting solid rock that serves as building stone.

Its resemblance to tuff does not make it volcanic tuff. The impact origin distinguishes the two materials.