Slate is a natural rock. To my ears it creats the softest sounds of any surface in pot calls. Slate will work in the rain if you use an acrylic striker. I havea couple of glass and crystal over slate double-sided calls that I really like. I use slate mostly to purr, cluck and tree call.

Ceramic - I never ran one. Can't help you there.

To my ears the surface that sounds the best is glass.Glass won't work inthe rain with any striker that I've found. Glass sounds good with a variety of strikers but my favorites are laminate wood one-piece and carbon/graphite.

Aluminum is my next favorite. Aluminum will work in the rain. It is typically higher pitched, louder, and makes a good locator call. I like purple heart, laminate, and carbon strikers with this surface.