180 DESCRIPTIONS OF MINERALS, 
soda bead in the outer flame is colored green by the manga- 
nese. 
Diff. Resembles magnetic iron, but the exterior color is a 
more decided black. ‘The streak is reddish brown, and the 
blowpipe reactions are distinctive. 
Obs. This is an abundant ore at Sterling and Hamburg, 
in New Jersey, near the Franklin Furnace; at the former 
place the crystals are sometimes four inches in diameter ; 
also amorphous at Altenberg, near Aix-la-Chapelle. 
Chromite.—Chromic Iron. 
- Isometric. In octahedral crystals, without distinct cleay- 
age. Usually massive, and breaking with a rough unpolished 
surface. 
Color iron-black and brownish black; streak dark brown. 
Lustre submetallic; often faint. H.-=5°. G.=4:3-4°6. 
In small fragments attractable by the magnet. 
Composition. General formula RR O,, as for magnetite ;. 
but part of the iron is replaced by chromium. Analysis 
gives Iron protoxide 32, chromium sesquioxide 68=100 ; 
aluminum and magnesium also are commonly present in 
variable amounts, replacing the other constituents. B.B. 
infusible alone ; with borax a beantiful green bead. 
This ore usually possesses a less metallic lustre than the 
other black iron ores. | 
Obs. Occurs usually in serpentine rocks, in imbedded 
masses or veins. Some of the foreign localities are the 
Gulsen Mountains in Styria; the Shetland Islands ; the de- 
partment of Var in France; Silesia, Bohemia, ete. 
In the United States it is abundant: in Maryland in the 
Bare Hills, near Baltimore, and also in Montgomery County, 
at Cooptown, in Harford County ; and in the north part of 
Cecil County ; occurs also in Townsend and Westfield, Ver- 
mont, and at Chester and Blandford, Mass. It is also found 
in Pennsylvania, at Wood’s Mine, near Texas, Lancaster 
County, in West Branford, Chester County ; at Bolton and 
Ham, Canada East ; in California near New Idria; also in 
Sonoma County; Tuolumne County, near Crimea House, 
and elsewhere ; at Seattle in Wyoming. 
The compounds of chromium, which are extensively used 
as pigments, are obtained chiefly from this ore. Meteorites 
have afforded a chromium-sulphide, named Dawbréelite. 

