IRON. Lay 
Red chalk. More firm and compact than red ochre, and 
of a fine texture. 
Jaspery clay iron. A hard impure siliceous clayey ore, 
and having a brownish-red jaspery look and compactness. 
Clay iron stone. The same as the last, the color and ap- 
pearance less like jasper. But this is one variety only of 
what is called ‘‘clay iron stone,” a name covering also a re- 
lated variety of siderite and limonite. he 
Lenticular argillaceous ore. A red ore, consisting of 
small flattened grains. 
Martite is hematite in octahedrons, derived, it is supposed, 
from the oxidation of magnetite. 
Composition. EeO*’=Oxygen 30, iron 70=100. B.B. 
alone infusible. Heated in the inner flame it becomes 
strongly magnetic. x 
Diff. The red powder of this mineral, and the magnetism 
which is so easily induced in it by a reduction flame dis- 
tinguish hematite from all other ores. The word hematite, 
from the Greek haima, blood, alludes to the color of the 
powder. 
Obs. This ore occurs in crystalline and stratified rocks of 
all ages. ‘The more extensive beds of pure ore abound in 
Archean rocks; while the argillaceous varieties occur in 
stratified rocks, being often abundant in coal regions and 
among other strata. Crystallized specimens are found also 
in some lavas, as a volcanic product. 
Splendid crystallizations of this ore come from Elba, whose 
beds were known to the Romans; also from St. Gothard ; 
Arendal, Norway ; Longbanshyttan, Sweden ; Lorraine and 
Dauphiny. Etna and Vesuvius afford handsome specimens. 
In the United States, this is an abundant ore. , The two 
Iron Mountains of Missouri, situated 90 miles south of St. 
Louis, consist mainly of this ore, piled ‘‘in masses of all 
sizes from a pigeon’s egg to a middle-si e church.” One of 
them is 300 feet high; and the other, the “ Pilot Knob,” is 
700 feet. The massive and micaceous varieties occur there 
together with red ochreous ore. Large beds occur in Essex, 
st. Lawrence and Jefferson counties, N. Y., and at Mar- 
quette, in Michigan; the micaceous variety, at Hawley, Mass., 
Piermont, N. H., and in Stafford County, Va.; lenticular 
argillaceous ore abundantly in Oneida, Herkimer, Madison 
and Wayne counties, N. Y., constituting one or two beds of 
the Clinton group (Upper Silurian), in a compact sandstone ; 
