Almost 15 years have passed since carbynes entered the literature as new forms of elemental carbon. They recently attracted attention as possible interstellar dust constituents and as carriers of presolar noble gases in meteorites. Their existence and that of the related mineral chaoite are questioned, and a reevaluation of previous data is suggested.

High-resolution transmission electron microscopy, shows that carbon in the Allende carbonaceous chondrite meteorite is predominantly a poorly crystalline graphite. Such material is of interest as an important carrier of the isotopically anomalous noble gases found in carbonaceous chondrites.

No abstract

No abstract

A basalt sample dredged from the axis of the Mid-Atlantic Ridge has been ion-thinned and examined by transmission electron microscopy. Finely dispersed particles as small as 0.04 μm in diameter, occurring in amorphous patches of the rock, have been identified as titanomagnetite by means of electron diffraction and microanalysis. These small particles have dimensions appropriate to single magnetic domain behaviour, and are considered to be largely responsible for the strong and very stable natural remanent magnetization of this rock.