Chrome chalcedony

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

                      Chrome Chalcedony

 

Chrome chalcedony occurs in a number of places in Western Australia. The piece displayed below came from near the town of Newman which is approximately 700 miles north of the capital, Perth.

The geological setting of the occurrence is that of an ultramafic intrusion into an area of granite-greenstone of Archaean age(>2500Ma)

The intrusion consists of serpentinite that has also produced chrysoprase, chalcedony & common opal. These rock types along with the chrome chalcedony occur in the weathered , silicified cap rock.

It is believed that original weathered serpentinite has been replaced through processes of silica deposition and the chrome chalcedony represents a whole-rock replacement or psuedomorph.

Chromium which is responsible for the green colouration of the chalcedony has originated from the existence of chromite within the serpentinite.

 

 

 

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