type of rock

CLAY
COAL
TALC
TUFF
CHALK
FLINT
SHALE
SLATE
BASALT
GABBRO
GNEISS
MARBLE
PUMICE
QUARTZ
DIORITE
LIGNITE
OBSIDIAN
PORPHYRY
CLAYSTONE
ANTHRACITE
List of words for the clue type of rock from the crossword:
EMO LAVA ACDC ARENA AGATE ACID REM STONE OPERA HAIR GEM AMEN ALTO MUSIC YES IRA IDOL NEON GENRE