Menilite
Image: <a href="//commons.wikimedia.org/wiki/User:Archaeodontosaurus" title="User:Archaeodontosaurus">Didier Descouens</a> (CC BY-SA 4.0)
Mineral NameMenilite
Chemical FormulaSiO₂·nH₂O
Mohs Hardness5.5
Crystal Systemamorphous
Lusterwaxy
Streak Colorwhite
Cleavagenone
Fractureconchoidal
Specific Gravity2.1
Colorsbrownish-orange, tan, light brown
Transparencytranslucent
Type LocalityPlateau de Merdogne, Puy-de-Dôme, Auvergne France
Mineral GroupSilicates
Usescollector, ornamental
Associated Mineralschert, limestone, diatomaceous earth
Raritycommon
Description
A chunky, irregularly shaped specimen of brownish-orange to tan menilite, exhibiting a waxy luster with some lighter, swirling patterns and a rougher, lighter-colored matrix attached.
Geological Context
Menilite is a variety of common opal (Opal-AG), a mineraloid formed from the precipitation of silica-rich solutions, typically found in sedimentary environments such as diatomaceous earth or chert deposits.
