Classification of Meteorites According to Their Chemical Composition

Abstract

Consideration of the main principles of classification of meteorites leads to the conclusion that the primary characteristic should be their chemical composition. From this point of view, the most correct classification was formulated by Prior; however, it needs further perfection.Definite properties were formed in the chemical composition of meteorites of all three classes, this enabled us to divide the classes into six subclasses: calcium-rich achondrites, calcium-poor achondrites, chondrites, siderolites (mesosiderites), lithosiderites (pallasites) and siderites. These differ in their total iron content, indicated in the ratio of silicate to metallic phase. Depending on the principal composition of the phase (the content of FeO in silicates and Ni in metal), the meteorites are divided into five groups, evidently related to the separate generative bodies.This distribution is of a distinct character, reflects the genetic connections between different types of meteorites, and can serve as a basis for their classification.Mineralogical and structural properties were taken into account, and a scheme for classification of meteorites according to their chemical-mineralogical composition and structure elaborated.. An interconnection has been found between the quantity of FeO in silicates and the content and composition of nickel-iron in chondrites, mesosiderites, and pallasites; this is called Prior's group law, as it is observed if meteorites of different groups are compared and absent inside the group itself.It is concluded that the above law characterizes processes that took place before matter broke up into groups; i. e. before the formation of bodies from which meteorites originated. --Auth.

Meteorite petrology versus genetics: Toward a unified binominal classification

“…The groups had genetic significance in the Prior (1916) picture of progressive oxidation anticorrelating with depth in a parent body. This conceptualization of the taxonomy was later adopted by Yavnel (1958), who ascribed his groups to different parent bodies. Mutatis mutandis (e.g., with isotopic ratios having superseded redox levels as genetic signatures), I propose to revive this two‐dimensional logic by redefining “groups” and “classes” in a unified way across meteorite categories as follows: A group is a genetically connoted taxon (hence the mnemonic G roup = G enetics), whose empirical definition is only slightly modified from the letter of Krot et al.…”