These are medium sized, high grade Mookaite Tumbled Stones.
These Tumbles are priced per single stone.
The average size & weight of these stones are:
20mm x 15mm x 15mm. 16g
Mookaite can be described as chert, opalite, chalcedony or combinations of the three.
The name "mookaite" is derived from the locality where the rock is dug, namely Mooka Creek. According to locals, the Aboriginal word "mooka" means "running waters", no doubt in reference to the many fresh water springs that feed Mooka Creek.
Mookaite is actually a fossiliferous sedimentary rock. The correct geological term for the formation that Mookaite occurs in is: Windalia Radiolarite. Microscopic examination of the Radiolarite has shown that this rock consists principally of the remains of tiny organisms known as Radiolaria, which possessed an unusual skeletal structure of opaline silica.