SI unit of amount of substance (4)

I believe the answer is:

mole

(Other definitions for mole that I've seen before include "beauty spot" , "Spot - burrowing mammal" , "Spy - one that burrows" , "Amount of substance" , "Spy - creator of hills?" .)

I've seen this clue in The Mirror.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.