Another week, another blue-chip in the dock. The US Securities and Exchange Commission has brought fraud charges against London-based mining giant Rio Tinto and two former executives in relation to an ill-starred coal venture in Mozambique. Whatever its legalities, this was a colossal corporate cock-up.

In 2010, Rio paid $3.7 billion for Riversdale, an Australian company that controlled large coal deposits in the Tete region of Mozambique.