20 Cents - Elizabeth II Sonic Boom

The "Sonic Boom" is part of a broader Solomon Islands promotional series aimed squarely at the novelty collector market, leveraging the islands' liberal commemorative minting arrangements — the country has long permitted foreign minting houses to produce coins under its authority with minimal restriction. This particular piece was almost certainly struck by a European or East Asian private mint, not by any domestic facility.

Silver-plated iron is a cost-reduction substrate common to this class of issue; the iron core corrodes aggressively if the plating is breached.