Attic insulation levels are measured by R-Value, which indicates resistance to heat flow. Most attics should be insulated to R-38, or about 10 to 14 inches, depending on the insulation type.
Mineral wool is a fiber insulation made from natural materials, similar to fiberglass but not from glass.
Insulation works by slowing conductive and convective heat flow, while radiant barriers and reflective insulation reduce radiant heat gain through reflective surfaces in contact with air spaces.