marblelike (?.)
- adamant
- adamantine
- bony
- cement
- cemental
- concrete
- corneous
- dense
- diamondlike
- dure
- flintlike
- flinty
- granitelike
- granitic
- hard
- hard as nails
- hardhearted
- horny
- iron-hard
- ironlike
- lapideous
- lithic
- lithoid
- lithoidal
- marble
- obdurate
- osseous
- petrified
- petrogenic
- resistant
- resistive
- rock
- rocklike
- rocky
- slaty
- solid
- steellike
- steely
- stone
- stonelike
- stony
- tough
