Powder mineral (4)
I believe the answer is:
talc
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">powder mineral</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for talc that I've seen before include "Bathroom powder (abbr)" , "Baby powder" , "After-bath powder" , "(Mineral providing) powder" , "Softest mineral on Mohs hardness scale" .)