Summary (click me!)
General
Ice fields spawn in volatile storms in HS, LS and NS. 7 units of a particular space's ore (can't turn in ice from HS at a LS site for example) have to be traded at the belt's local Orca for a box of loot.
LS boxes are assumed to be the most valuable ones, followed by NS and then HS.
One can acquire upgraded boxes by turning in Cryograph- items (dropped by Yoiul LADs).