The occurrence and origin of lamellar troilite in iron meteorites

A number of iron meteorites contain elongated inclusions consisting predominantly of troilite, which have been termed Reichenbach lamellae. Two types of inclusions exist, the first up to 6 cm long and 0·2 mm wide, the second up to 2 cm long and 3 mm wide. The first type contains troilite with subordinate daubreelite and is commonly rimmed by schreibersite and swathing kamacite; the second consists largely of troilite with daubreelite and rare graphite and silicate grains.

Both types formed from a residual sulfide melt after the solidification of NiFe metal. Swatching kamacite surrounding troilite in iron meteorites formed by nucleation at the troilite-metal interface during the formation of the Widmanstätten texture.

Meteorites containing troilite inclusions of the second type appear to have cooled more rapidly than most iron meteorites.

In view of the confusion surrounding the use of the term Reichenbach lamella, it is suggested that the term be dropped from the literature.