Pietra dell'Etna, from Mt. Etna, Catania, Sicily, Italy
Geological description:
Altered (?phonolitic) tephrite. It is brecciated, but similar in mineralogy to no. 664. Prominent black pyroxenes occur within and separated from the clasts. These also contain a strongly altered felsic mineral. The matrix is white carbonate, but the lack of rounding of pyroxenes suggests that it has infiltrated the rock, and not entered as a result of fracturing and movement.