Burger will deliver the final lecture in the masterclass series on the National Gallery of Australia's Gold and the Incas exhibition masterclass series on Wednesday.

Burger said he would be discussing the exhibition in the context of "how people came up with the idea of working metal and how they used it and how that related to change in society".

He said, "Two of the pieces I'll be talking about are things I discovered myself as a field archaeologist in Peru."

One, found in the Andes and dating from 1400BC, was the size of a fingernail. It was a copper sheet on which were pasted pieces of gold. He said the two metals were used for contrast to indicate the forces of dualism in the universe.

The other, dating from about 700BC, was a piece of gold jewellery – "the only piece of gold found in context in Chavin" – which had been soldered, showing people knew how to change the composition of an alloy through temperature.

He said, "The early development of metallurgy was in conjunction with religion."

In Peru the earliest discoveries date to 2000BC but there was a "real revolution" with the advanced Chavin culture about 800BC-500BC.

"It was the first civilisation in the Andes in which there was differentiation, specialisation and great art."

Previously metals had been used only in their pure form but the Chavin people mixed alloys – such as gold and silver – and created crowns, nose ornaments and other adornments that were worn by the elite of society such as priests.

Professor Richard Burger's master-class lecture on Gold and the Incas is on Wednesday March 26 at 6pm in the gallery's James O Fairfax Theatre.

Single tickets are available at the door:$35 full price, $30 concession, $25 members. The one-hour lecture will be followed by an exhibition viewing from 7 to 8pm.