White crystals of the rare silica-hydrocarbon minerals chibaite (IMA 2008-067) and bosoite (IMA 2014-023) from the type and only known locality worldwide for both species: Arakawa, Minamiboso City, Chiba Prefecture, Honshu Island, Japan. Chibaite and bosoite can't be visually differentiated. Natural analogues of synthetic clathrate MTN with hydrocarbon molecules such as methane, ethane, propane, and 2-methyl-propane contained in its cage-like voids. Chibaite and bosoite are also described as a clathrasils. Ex Alfredo Petrov specimen. — Photo: David Hospital · CC BY-SA 4.0
Bosoite
Bosoite is an IMA-recognized mineral species in the organic mineral class, with the chemical formula SiO₂·nCₓH₂ₓ₊₂.
It crystallizes in the hexagonal crystal system (space group P6/mmm).
Key properties: Mohs hardness 6.5–7; specific gravity 2.04; White streak; Vitreous luster; optically uniaxial.
IMA symbol Bs, IMA status: approved, named in 2014.
Formed under low-temperature conditions during diagenesis of tuffaceous forearc sandstone and mudstone.
It is found associated with Chibaite, quartz, calcite.
The name refers to the Boso Peninsula, east of Tokyo across Tokyo Bay.