more socks: materials, not colors

The formula for winter hosery I've found most successful is knee-high silk linings under knee-high wool socks. The whole wicking underlayer with insulating outerlayer really seems to work, the nice socks are largely protected from my skin and sweat, and the wool doesn't itch, and the knee-lengths both insulate and stay up better.

What have people found for summer hosery? Is merino wool as cool as some retailers claim, or is cotton preferred? Or silk, and if so, where can non-formal silk socks be bought?