[ 'basɔ:lt , -(ə)lt ]
■ noun a dark fine-grained volcanic rock composed largely of plagioclase with pyroxene and olivine.
Derivatives
~ic bə'sɔ:ltɪk adjective
Origin
C17: from L. ~es (var. of basanites ), from Gk basanitēs , from basanos 'touchstone'.