fine
powdered
powdery
pulverized
small-grained
smooth
Carboniferous
argillaceous
bituminous
brownish
calcareous
clayey
columnar
crumbly
crystalline
ferruginous
friable
granular
gritty
metamorphic
pebbly
pliable
porous
quartzose
schistose
silicious
stratified
coarse-grained