XML : How to use material spinner item layout?

My theme is based on Theme.AppCompat and the Spinner I use is a simple (?) Spinner UI element.

The Spinner button itself is in material design, but once I click on it I don't get a list of material spinner items.

This is how I load up my adapter

  ArrayAdapter<string> adp = new ArrayAdapter<string>(this,       global::Android.Resource.Layout.SimpleSpinnerItem,      _spinnerContent);    

How can I use the material spinner item?