Hello Robert.
As NETWizz mentioned, they are not compatible for stacking,they are from different families.
We support a Mixed stacking, but that would be between ICX 6610 devices and ICX6450 devices.
Please check the link below for further information:
http://docs.ruckuswireless.com/fastiron/08.0.30/fastiron-08030b-switchstackingguide/GUID-89D1A468-14ED-4C9C-A065-1E579B488AEA.html