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The Oxidation of Meteorites *
Author(s) -
Buddhue John Davis
Publication year - 1939
Publication title -
contributions of the society for research on meteorites
Language(s) - English
Resource type - Journals
eISSN - 1945-5100
pISSN - 0096-2813
DOI - 10.1111/j.1945-5100.1939.tb00208.x
Subject(s) - meteorite , kamacite , nickel , oxide , metal , geology , mineral , astrobiology , mineralogy , chondrite , materials science , chemistry , metallurgy , physics
The oxide of iron meteorites is typically laminated and magnetic, with a specific gravity of 2.92 to 4.24, and dark brown to black in color. Some occurs as shale‐balls, which may result from an abundance of lawrencite. These seem to be a special case of the ordinary rusting of iron masses. Shale‐balls resemble certain lava‐bombs, but one such mass is known which is non‐lamellar and contains traces of Widmanstätten figures. These figures have been seen also in Canyon Diablo, Arizona, oxide. Their preservation may be the result of the oxidation's having begun between the kamacite bands. This type of oxidation is also responsible for the presence of the metallic particles which are found in oxides. A meteorite in an intermediate stage is known. Schreibersite particles are found because of their resistance to oxidation. Oxides from Willamette, Oregon, and Odessa, Texas, are described and analyses given. The oxidation of meteorites is accelerated by electrolytic action between the constituents and by the action of lawrencite. Many oxides bear green stains. In four cases these have been identified as deposits of zaratite. The presence of this mineral and various experiments show that all the nickel need not enter the oxide, and that nickel can be removed by solution. Comparison of nickel contents of oxides and the unaltered metal shows that the oxide contains almost invariably less nickel than the metal. Hence, ancient meteorites may be unrecognizable because they have lost all their nickel. The mineral composition of the oxides is very imperfectly known. Rustite and ayasite are suggested as possible names.