The barberini ivory is a great example of the what?

It depends on what type of third separates the three notes.for example: if you have two mayor thirds is an "aumented chord"if you have two minor thirds is an "diminued chord"if you have one mayor first and then one minor is a "mayor chord"and inverted is a "minor chord"

Opposition of two melodic ideas is the  right answer 

Ilike the chat because if someone has missed anything off their answer they can put it in the chat