Check out Prof William Jolly's article 'Silver Mirror and Other unusual B&W printing processes' (and a subsequent update) in Photo Techniques Magazine (US). This process provides incredible Daguerrotype-like mirror finish prints, but is involved and a touch tricky to get to work properly.(posted 8602 days ago)You can use Halochrome on FB paper but I suggest RC for 2 reasons - no silver mirror print is as archival as a regular silver/gelatine print (the silver is ~very~ vulnerable to aerial oxidation - take a look at any old Daguerrotype) furthermore the prints on RC paper are more 'mirror-y' because of the inherent reflectivity of the polyester base.
I have made portraits and done them both with Halochrome and Prof Jolly's silver mirror technique and they are stunning, but all look a bit similar after a while. For a really freaky 'brushed chrome look' print portraits on heavily textured watercolour paper coated with Luminos Silverprint liquid emulsion and then Halochrome them. ~Weird~.
Later,
Marty