Having been so diligently patient over the first three years of life outside of BHP Billiton, it does seem just that little bit odd that South32 has moved to spend $US1.4 billion ($1.88 billion) on an undeveloped zinc and silver project in Arizona at a time of cyclically high zinc prices.

South32 chief executive Graham Kerr accepted this observation with knowing resignation as it resounded repeatedly through Monday morning's deal confirming set pieces with analysts, media and senior investors.