Ash is found throughout Europe, which is where this genus and species grow.  The term Olive Ash is used to describe flat sliced veneer with a mixture of the white / yellow Ash color and a brown to olive color which looks to be interlocking with one another, similar to what you would see in true Olivewood.  Sometimes darker striations or dark veins can also be found within the mix.  Some logs will also develop a figure such as crossfire.

Like Maple and Birch, Ash is mainly comprised of sapwood.  The heartwood is where we see this change in color.  So, it might seem as though the “Olive” look would be readily available.  Yes and no.  The “Olive” coloration is generally clipped out of the veneer, leaving only the sapwood, because that’s what the market wants.  Only select logs that look to have an abundance of heartwood when you inspect them on the log yard, will be sliced in hopes of achieving mainly Olive Ash.  Another example of roll the dice in our industry.  You never really know what the log is going to actually yield until you begin slicing it.  .