The rocks around the site were clearly a greenish-blue copper carbonate colour.
However the rocks around the cave entrance were more of blue colour.
hydrating the copper and giving rise to the classic Cu2+ colour.
The basic copper carbonate is green-blue colour and is called Malachite (Cu2CO3(OH)2).
|Raphael, Madonna and Child Enthroned with Saints, The Metropolitan Museum of Art|
A painting with it particulary well preserved is Hans Holbein's Lady with a Squirrel and a Starling.
|Hans Holbein the Younger, Lady with a Squirrel and a Starling, National Gallery, London|