A brief summary is given of the circumstances attending the observation of, the search for, and the recovery of the achondrites that fell on February 18, 1948 in Kansas and Nebraska. The main mass of this achondritic fall is not only the largest known aerolite in the world but also the largest meteorite of any type of witnessed fall. The weight of the principal mass is inferred to be at least 2360 pounds and the integrated weight of the recoveries so far made is estimated as in excess of 2500 pounds. The recovered achondrites serve as the type stone of a new achondritic subclass, the nortonites, intermediate between the aubrites and the Cumberland Falls whitleyite.

Brief details are given on the distribution of nortonite recoveries, on the apparent and corrected radiant of the shower, and on the real path of the fireball.

The mineralogy of the nortonites is discussed. Megascopically, this achondrite resembles a rhyolite porphyry in which the “phenocrysts” are grayish cleavage enstatite and glassy enstatite, and the fine-grained “groundmass” seems to be solely enstatite. Closer inspection reveals inclusions of nickel-iron pellets; abundant, small flakes of graphite; diallage; and iron-rust stains. Microscopic examination in thin sections and oil immersions confirms the megascopic examination, and reveals that olivine is fairly abundant. Clinoen-statite is intergrown with enstatite in some crystals. Optical constants are given for enstatite and olivine. The meteorite has a fusion rind ranging from 0.2 mm. to at least 17.7 mm. The rind is holocrystalline and is very fine grained.

A polished section of one nickel-iron inclusion was studied. The metallic phase is made up of kamacite and schreibersite. Small amounts of troilite were noted in other metallic inclusions but none in the polished specimen.

Chemical and spectrographic analyses of the stony and metallic phases are given. Tests have been run at the Institute for Nuclear Studies of the University of Chicago on nortonite samples in an effort to detect radioactivities induced by exposure to cosmic radiation. To date, no evidence of such radioactivities has been obtained.

The recovery of this achondrite gives strong support to the “meteorite-planet” hypothesis favored by Boisse, Farrington, and Harrison Brown.

Eight figures and two tables are given.

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