32 
HALL 62. 
METEORITES. 
The collection of Meteorites includes representatives of 
about 250 distinct “falls” or “finds,” the specimens having an- 
aggregate weight of 5,130 pounds (2,327 kilograms). 
These are grouped in three classes, viz. : — Siderites (iron 
meteorites), Siderolites (iron-stone meteorites), and Aerolites 
(stone meteorites). Under each of these divisions the speci- 
mens are placed in chronological order, and labels show the 
locality, date of fall or find, and weight of specimen. 
The specimens are in large part not the individual stones 
but fragments of them, it being usual when a meteorite falls 
or is found, to break it up and distribute the pieces among 
museums and collectors in order to provide material for 
study. Otherwise meteorites could be studied only by going 
from one museum or collector to another. The total number 
of falls and finds now recognized is about 650. 
CASE 1. — Siderites, These are meteorites composed chief- 
ly of iron, with varying percentages of nickel, cobalt, mangan- 
ese, etc. Combined sulphur and phosphorus are usually present. 
The surface of the siderites is usually smooth as if fused, and 
more or less indented or pitted. In the interior they have a 
silvery luster. Polished slabs, upon etching with acid, usually 
show regular markings called Widmannstfitten figures. Acord- 
ing to the character of these figures the siderites are further 
divided into octahedral and cubic irons and the octahedral irons 
into those of coarse, medium and fine laniellae. 
The specimens shown are largely sections from the original 
masses and most of them polished and etched. The shape of the 
original mass is often to be seen illustrated by a cast in the ad- 
joining case. 
Among the specimens may be noted as of especial interest, 
the series of Toluca, Mexico, irons, more than twenty masses 
and slabs of which are shown. Such masses have been ploughed 
up at intervals about Toluca since 1784. They long furnished ft 
source of iron to the natives, and one of the specimens shown 
was once in use as a hammer. The Bemdego, Brazil, iron, two 
sections of which are shown, was also discovered about 1784» 
