Answer: andesite

AnswerCrossword Clue
ANDESITEVolcanic rock
andesitean extrusive usually dark grayish rock consisting essentially of oligoclase or feldspar
andesitea volcanic rock, also ANDESYTE
andesitedark-colored volcanic rock composed essentially of plagioclase feldspar and one or more mafic minerals, as hornblende or biotite