Cliftonite is a natural form of

graphite Graphite () is a Crystallinity, crystalline allotrope (form) of the element carbon. It consists of many stacked Layered materials, layers of graphene, typically in excess of hundreds of layers. Graphite occurs naturally and is the most stable ...

that occurs as small octahedral inclusions in iron-containing meteorites. It typically accompanies kamacite, and more rarely schreibersite, cohenite or plessite. Cliftonite was first considered to be a new form of carbon, then a pseudomorph of graphite after diamond, and finally reassigned to a pseudomorph of graphite after kamacite. Cliftonite is typically observed in minerals that experienced high pressures. It can also be synthesized by annealing an Fe-Ni-C alloy at ambient pressure for several hundred hours. The annealing is carried out in two stages: first a mixture of cohenite and kamacite is formed in air at ca. 950 °C; it is then partly converted to cliftonite in vacuum at ca. 550 °C. The Campo del Cielo region of

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

is noted for a crater field containing a group of distinctive iron meteorites.

References

{{reflist Native element minerals Allotropes of carbon Hexagonal minerals Minerals in space group 194