Guess the Ingredient Soap

Black Sesame Seeds Soap
Soap made of castor oil, grapeseed oil, coconut oil, olive oil, shea butter, palm oil, almond oil, Eucalyptus Citriodora essential oil , zinc oxide. I have used an ingredient which I have never used before and which gave the soap this rustic dark grey colour. For the  upper layer I used some oxid zinc.

The one who guesses first the ingredient I used, receives a bar of this soap!sapun cu seminte de susan negruHere are some hints:

One of the oldest condiments known to man
Think antioxidants
Think vegan
Think healthy
Sesamum indicumTomorrow I will reveal some more hints!
Soap with black sesameGood luck!