Pallasites

Pallasites are a class of stony-iron meteorites characterized by a matrix of iron-nickel metal in which olivine crystals are embedded. They are among the most striking meteorites because of the contrast between the metallic regions and the translucent olive-green olivine grains.

Mineralogy and texture: The metal phase typically consists of kamacite and taenite, while the silicate component is olivine, usually high in magnesium as forsterite. Olivine crystals in pallasites range from a few millimeters up to several centimeters and are embedded in a predominantly metallic host, giving a mosaic or pepper-and-salt appearance when cut and polished.

Formation and origin: Pallasites are believed to originate at the boundary between metal and silicate during the differentiation of a parent asteroid. In some scenarios, chunks of olivine-rich mantle were incorporated into molten metal that later cooled to form the characteristic metal-olivine mixture. This makes pallasites valuable records of processes at the core–mantle interface of differentiated bodies.

Classification and notable specimens: The majority of pallasites are classified as main-group pallasites, with a smaller number remaining ungrouped. Well-known examples include the Gibeon meteorite from Namibia, and the Esquel and Brahin specimens, which are frequently cited in demonstrations of their distinctive structure.

Scientific significance: Pallasites offer rare direct samples from the interior regions of differentiated bodies, contributing to studies of planetary differentiation, cooling histories, and the interactions between metal and silicate during early solar system evolution. They are widely collected for both scientific value and their aesthetic appearance.