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Menilite is a greyish-brown form of the mineraloid
/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
Menilite is a greyish-brown form of the mineraloid opal
Opal is a hydrated amorphous form of silica (SiO2·''n''H2O); its water content may range from 3 to 21% by weight, but is usually between 6 and 10%. Due to its amorphous property, it is classified as a mineraloid, unlike crystalline form ...
.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
Ménilmontant () is a neighbourhood of Paris, situated in the city's 20th arrondissement. It is roughly defined as the area north of the Père Lachaise Cemetery, south of Parc de Belleville, and between ''Avenue Jean-Aicard'' on the west and ...
(Paris
Paris () is the Capital city, capital and List of communes in France with over 20,000 inhabitants, most populous city of France, with an estimated population of 2,165,423 residents in 2019 in an area of more than 105 km² (41 sq mi), ma ...
), France
France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of overseas regions and territories in the Americas and the Atlantic, Pacific and Indian Oceans. Its metropolitan area ...
, where it occurs as concretion
A concretion is a hard, compact mass of matter formed by the precipitation of mineral cement within the spaces between particles, and is found in sedimentary rock or soil. Concretions are often ovoid or spherical in shape, although irregular ...
s within bituminous
Asphalt, also known as bitumen (, ), is a sticky, black, highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term ...
Early Oligocene
The Rupelian is, in the geologic timescale, the older of two ages or the lower of two stages of the Oligocene Epoch/ Series. It spans the time between . It is preceded by the Priabonian Stage (part of the Eocene) and is followed by the Chattian ...
Menilite Shales.
See also
*Geyserite
Geyserite, or siliceous sinter, is a form of opaline silica that is often found as crusts or layers around hot springs and geysers. Botryoidal geyserite is known as fiorite. Geyserite is porous due to the silica enclosing many small cavities. S ...
* Hyalite
Hyalite is a transparent form of opal with a glassy lustre. It may exhibit an internal play of colors if natural inclusions are present. It is also called Muller's glass, water opal, and jalite. Müller's glass is named after its discoverer, Fr ...
References
Opals {{Mineral-stub