HANDBOOK AND DESCRIPTIVE CATALOGUE OF THE 

 METEORITE COLLECTIONS IN THE UNITED STATES 

 NATIONAL MUSEUM. 



By George P. Merrill, 

 Head Curator of Geology, United States National Museum, 



PART I. 



INTRODUCTION. 



The name meteorite is given to the masses of metal and mineral 

 matter which come to the earth from space in the form of falling 

 bodies and which are commonly considered identical in nature with 

 the meteors, or so-called shooting stars, which on clear nights may 

 often be seen darting rocket-like across the sky. The origin of these 

 bodies was for a long time in question, and even now we are quite in 

 the dark concerning their ultimate source, though there is apparently 

 little doubt that they are from regions outside of our solar system and 

 come to us in the form of gradually disintegrating comets. 



The elemental matter of meteorites is the same as that of the earth, 

 though differing apparently in proportional amounts and certainly 

 often in form of combination. The most abundant of the meteoric 

 elements are, named in alphabetical order: Aluminum, Calcium, Car- 

 bon, Iron, Magnesium, Nickel, Oxygen, Phosphorus, Silicon, and 

 Sulphur. More rarely and in smaller quantities are found Chlorine, 

 Chromium, Cobalt, Copper, Hydrogen, Iridium, Lithium, Manga- 

 nese, Nitrogen, Palladium, Platinum, Potassium, Ruthenium, So- 

 dium, Titanium, and Vanadium, probably also Argon and Helium. 

 The presence of Antimony, Arsenic, Gold, Lead, Strontium, Tin, and 

 Zinc has from time to time been reported, but recent investigation 

 has thrown doubt upon the correctness of the determinations.^ 



Meteorites vary in composition from those which are composed 

 almost wholly of the silicate minerals, olivine and pyroxene, with 

 perhaps a little feldspar, to those which are almost wholly of nickel- 

 iron. Frequent gradations are met with, but nevertheless it is pos- 



» Merrill, On the minor constituents of meteorites, Amer. Journ. Sci., vol. 35, 1913, p. 509. 

 5692°— Bull. 94—16 1 1 



