plagioclastic

/ˌpleɪdʒiəˈklæstɪk/
adjective
  1. Relating to or containing the mineral plagioclase.
    • The plagioclastic crystals in the rock were easy to see with a hand lens.
    • This plagioclastic lava flow cooled slowly underground.
    • The lab report described the sample as highly plagioclastic.