Explanation:
Rare property of obsidian that is advantageous to archaeologists is that it occurs in volcanic flows that are remarkably homogeneous in chemical composition within a flow, but preserve elemental signatures that are unique to volcanic centers, and in some cases individual flows.
Answer:
The presidency of Nelson Mandela began on 10 May 1994, when Nelson Mandela, an anti-apartheid activist, lawyer, and former political prisoner, was inaugurated as President of South Africa, and ended on 14 June 1999.
Explanation:
