Michael Swan mentions it in noun+noun:advanced points.
n+n is normally used to say what things are made of; a silk dress, a stone bridge, an iron rod. So... a glass pane, a paper sheet. a cloth bolt.
In older English the
of structure was more common but is still used today (as in your examples)
A rod
of iron, a bridge
of stone, a dress
of silk etc.
I personally am not about to lose sleep over it.
