Quote Originally Posted by Definition of Natural
A substance that is derived from mineral, plant, or animal matter and does not undergo a synthetic process as defined in section 6502(21) of the Act (7 USC 6502(21)). For the purposes of this part, nonsynthetic is used as a synonym for natural as the term is used in the Act.

Natural is defined as "of or relating to nature"; this applies to both definitions of 'nature': 'essence' ("one's true nature") and 'the untouched world' ("force of nature"). Natural is often used meaning "good", "healthy", or "belonging to human nature".
Quote Originally Posted by Definition of Chemical
# produced by or used in a reaction involving changes in atoms or molecules
# of or made from or using substances produced by or used in reactions involving atomic or molecular changes; "chemical fertilizer"

Refers to human-made or synthetic compoundsā??or not of natural origin.

A chemical compound is a substance consisting of two or more chemical elements that are chemically combined in definite proportions.
Well...just from reading these two I would just go with natural lol.