Actinolite mineral from Dookie Mineralogical Reserve quarry.
Source: Museum Victoria
Axinite-(Fe) (Ferroaxinite) mineral from Lake Cooper quarry.
Image: Frank Coffa
Source: Museum Victoria
Andradite mineral from Dookie Mineralogical Reserve quarry.
Image: Frank Coffa
Source: Museum Victoria
The higher temperature and pressure exerted on the buried volcanic rocks changed their mineral composition – a process called metamorphism. Super-hot fluids moved through fractures and pores in the rocks, carrying dissolved elements such as calcium, iron, aluminium and boron. When the fluids cooled, minerals such as garnet and axinite crystallised in open spaces in the rocks.