Full Idea
Although your heart is a material object, the property of being a heart is, if we accept the functionalist picture, not a material property.
Gist of Idea
Hearts are material, but functionalism says the property of being a heart is not a material property
Source
John Heil (Philosophy of Mind [1998], Ch.4)
Book Reference
Heil,John: 'Philosophy of Mind' [Routledge 1998], p.97
A Reaction
Presumably functional properties are not physical because they are multiply realisable. The property of being a heart is more like a theoretical flow diagram than it is like a muscle. That word 'property' again…