"Munjina Stone” is from the Chichester Ranges in the Pilbara region of Western Australia, approx. 800 miles N. of the capital, Perth. It occurs in the Jeerinah Formation which is part of the Fortescue Group in the Hamersley Basin.. It is the same formation the Noreen -Jasper does occur. Age is late Archaean and was deposited between 2765 & 2687 million years ago. It is a silicified pelite (mudstone).
More Informations are given on the website of Glenn Archer www.outbackmining.com