A form of gypsum or perhaps Arab slate (9)
I believe the answer is:
alabaster
'a form of gypsum' is the definition.
(I've seen this before)
'perhaps arab slate' is the wordplay.
'perhaps' indicates anagramming the letters.
'arab'+'slate'='arabslate'
'arabslate' is an anagram of 'ALABASTER'.
'or' acts as a link.
(Other definitions for alabaster that I've seen before include "Sculptors work with this" , "statue material" , "Blast area for white mineral" , "Material for sculpting" , "Stone often used for carving" .)