Menilite
Menilite is a greyish-brown form of the mineraloid opal.<ref name=Mindat>Menilite on Mindat.org</ref> It is also known as liver opal or leberopal (German), due to its color. It is called menilite because it was first described from Ménilmontant (Paris), France,<ref name=Mindat/> where it occurs as concretions within bituminous Early Oligocene Menilite Shales.