Sorry to disagree but we usually use a mixture of green and black to make oil.
They become black as they hang on the tree longer. I'm sure someone will
explain better than I.

Trudy Hollinshead
Quoting SummitTalent@aol.com:


>
> Which olives, the black or the green, are more suitable for the
> production of olive oil.
>
> There is no such thing as Black Olives... Black Olives are treated or
> De-Bittered for eating- The Black color comes from the process. All Olives
> are green for oil.