"Andamooka Black Opal Matrix"  a simple explaination:

"Andamooka" is a opal mining town in the outback of South Australia, situated about 300 miles to the south and east of the more well known Coober Pedy.

"Black" is a generic term for the treated base or background color of the Andamooka Opal Matrix Stone.

"Opal" is basically silica which has retained a small water content, SiO2.nH2O.

"Matrix" "the matrix" is a host stone where the opal silica has infused into it.

Andamooka Black Opal Matrix is a recognized opal type that is unique, very rare and only found on the opal fields at Andamooka.

The Matrix stone has some degree of porosity. During geological formation in the Cretaceous Period the opal silica infused into or onto this stone. 

Tiny particles of colored opal silica will give a "Pinfire" pattern, a stone with a higher concentration will give a more flashy gemmy appearance.

Not all opal silica has fire and this is called opal potch which can vary from translucent to transparent and from clear, white, through to black color.

When Andamooka Opal Matrix is pulled from mother earth, it just looks like any other light colored rock !

Wet it and it is easier to see whether there is colored fire within.

To enhance the visability of seeing the colors the matrix is treated "Black".

This is done by cooking the stone in sugar, later the sugar is carbonized thus giving the stone a darker or black background.

Basically there are two types of Andamooka Opal Matrixes:

(1) we sell mostly the harder more gemmy type that will take a polish finish.

(2) is from a sandstone host stone known locally as aka: "Concrete". Here on eBay we see it selling as "Rainbow Opal Matrix". It is a more porous stone and will not readily polish. It needs to be sealed with Opticon or similar to give it a shiny appearnce.

We Offer Our Customers a link to our website for DIY, Treating Recipes and Finishing Hints etc. 

I have kept the specifics of this guide fairly simple. I hope it is of some use for you to understand a little more about

"What is Andamooka Black Opal Matrix".

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