55ct Rough Andamooka Rainbow Matrix Opal Slice (11g, 0.40oz)

Andamooka rainbow matrix opal (AKA Concrete) found in Andamooka South Australia.  

Rainbow Matrix is an affordable way to create great looking black opals, with the added protection of a glassy resin coating.


Pictures taken wet.

Has been; sliced to show face of the stone, permanently darkened to N3/N4 with a single sugar carbon and heat treatment. - easier treatment method due to properties of this material. *

Please refer to pictures and video for size and quality. - WYSIWYG

Can be cut into stones, used for carving, or kept as a specimen.

If cutting and shaping is deep then the material may require a further darkening treatment. - There are many resources online that show who to do this. 

* Treatment Process: 
Dissolve sugar into hot water at about 50/50 ratio,
Place stones into sugar water mixture for 1 day, 
Take stone(s) out of sugar water mixture and dry naturally for 1 day,
Place stone(s) individually in a double piece of tin foil (aluminium foil) and add spoon full of vegetable oil (any),
Wrap the foil around the stone(s) - not too tightly,
Place stone(s) in foil onto a BBQ - medium heat with closed lid for 1 hour,
Turn off BBQ and leave it for 2 hours to cool.

Clean the carbon off the face of the stone (with a CAB, Rotary, Sander) and Ta-Da!


Finish a stone in 3 steps:
Shape and rub stone down to at least 2000 grit,
Wash and then dry the stone thoroughly,
Coat in a two part epoxy resin for a glassy finish.


We do not use acid to treat our Andamooka or Fairy opal material.

Will combine shipping. 

All items sent registered mail Australia Post


International buyers please note:
Import duties, taxes and charges, if any, are the buyers responsibility