38 
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 Widmanns fatten figures. 
According 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 lamellae. The speci- 
mens 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 adjoining case. 
Among the specimens may be noted as of especial interest, 
the series of Toluca, Mexico, irons, more than twenty masses 
and slabs being shown. Such masses have been ploughed up at 
intervals about Toluca since 1784. They long furnished a 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. It is a mass of 
great weight. A large series of siderites from Canon Diablo, 
Arizona, is shown and some etched slabs. There are also many of 
the Santa Catharina, Brazil, masses which are much oxidized. 
These have so high a content of nickel that their meteoric origin 
has been doubted. Other siderites exhibited in large quantities 
are the Kenton Co. Ky. 100 lbs., the Floyd County, Virginia, and 
Ellenboro, N. C., almost entire and Los Reyes, Mexico, entire. 
Widmannstatten figures of great beauty may be noted on the 
Lion River, Tazewell, Smith Mountain, Carlton and other sec- 
tions . 
Case 2 — Siderolites. These contain metallic and stony mat- 
ter in about equal proportions and form a transitional group be- 
tween the siderites and aerolites. Frequently the structure is that 
of a spongy mass of iron, whose cavities are filled with olivine. 
Specimens from fifteen localities are shown including one com- 
plete individual of the Rockwood, Tenn. , find. 
Aerolites. These are meteorites made up largely of stony 
matter. The surface is usually black, smooth as if fused, and 
somewhat pitted. On breaking the thin, black crust which covers 
the exterior, the interior is generally found to be of a grayish 
color, with scattered metalliferous particles. Analysis shows 
these meteorites to be made up largely of olivine, enstatite and 
