Most of it occurs in the Eastern Goldfields area near the towns of Leonora, Kalgoorlie and Norseman. 

Dendritic Moss Agate is a variety of Chalcedony with tree-like natural inclusion in the opal stone, and frequently containing green mineral inclusions, such as Chlorite, Hornblende, etc., or brown to black dendrites of Iron or Manganese Oxides.

It's a name given to any common opal with a tree or fern like silicates or manganese oxides. The Mohs scale in hardness is 7.

This listing is for a cabinet size rough specimen of Dendritic Moss Agate originating from the mining area called Grant's Patch, 50 km North West of Kalgoorlie, Western Australia. It measures approx. 87 x 60 x 32 mm at widest points, and weighs 162 g.