431 
Geology . 
8. Chrome.— Needle-ore and chrome- ophre are the 
only ores of this metal hitherto described. These occur 
imbedded in common quartz, accompanied with lead- 
glance, different ores of copper, and traces of native gold, 
all intimately aggregated together. Hence it is probable, 
that these ores occur in a bed in primitive rocks. Chrome, 
however, colours several fossils, whose relative age is bet- 
ter known. Thus it gives the beautiful green colour to 
the emerald of Peru, which occurs in clay- slate; the 
deep blood-red colour to the pyrope, an inmate of the se- 
cond serpentine formation, and wacke ; the beautiful se- 
ries of red colours to the oriental ruby, which is conjec- 
tured to occur in the newest flcetz-trap formation, and pro- 
bably in certain primitive rocks ; the aurora-red colour 
to the red-lead of Siberia, whose geognostic situation, 
however, is but imperfectly known ; and, lastly, the green 
colour to serpentine, and the red colour to spindle.* 
9. Bismuth. — ' This metal occurs in veins that traverse 
gneiss and mica- slate, and is accompanied with cobalt and 
silver ores. 
10. a. Native arsenic, — occurs almost always in pri- 
mitive mountains, and most frequently in veins, except- 
ing a small portion that appears in beds in the Bannat of 
Temeswar. 
h. Arsenic pyrites,— which is a combination of arsenic, 
iron and sulphur, occurs in beds in mica-slate at Reichen- 
stein in Silesia ; and in a similar repository in the newer 
granite of Zinnwald. It occurs also in veins that traverse 
gneiss ; as in the vicinity of Frey berg, in the electorate 
of Saxony, where it is highly characteristic for certain 
metalliferous formations ; in veins that traverse clay-slate, 
as in the Saxon Erzgebirge, and in veins that traverse 
* This metal, with iron, manganese, and nickel, occurs in aero- 
lites, those stones that fail periodically, and in the direction of the 
magnetic meridian, from the atmosphere. 
Chrome combined with iron occurs in the steatite of the vicini- 
ty of Philadelphia and Baltimore, T. C. 
