How to export an animated object from Blender to an .usdz-file for Reality Composer (AR)? I'm totally new to Blender. 

I only need it to make a rectangle with an animation that extrudes or scales over one axis over time.
So I keyframed X-Scale of a rectangle and tried to export it in an .abc-file, then tried to convert it to a .usdz-file via my terminal.


But when I do this I only get a simple cube without animation and without material.

Does anyone know how to do this?
Thanks in advance.
export animated .DAE file first, and then open with Xcode, Xcode allows you export .USDZ file, this step works great for me, hope it helps.