To install insulation in a crawl space, cover the vent openings with crawl space vent covers, seal the rim joists with rigid foam board insulation, and use foam sealant to seal gaps between the crawl space wall and sill.
Mineral wool is a fiber insulation made from natural materials, similar to fiberglass but not from glass.
Faced insulation has kraft paper attached to it, which enhances its sturdiness and prevents it from falling. Unfaced insulation lacks this paper but performs similarly.