Geology , 42g 
e. /^mVzif.—Hitherto this fossil has been found only 
in the high Riesen mountains, which separate Silesia 
from Bohemia, near the origin of the Iser, dispersed 
through the granitic sand which forms the bed of that ri- 
ver. To what order of rocks it owes its origin, is uncer- 
tain ; but its near affinity to iron-sand, which is exclu- 
sively an inmate of the newest flcetz-trap formation ; and 
the certainty that this formation was formerly superstrati- 
fied, at a great elevation, on the Riesen mountains, (as 
the remains which form the Buchberg, and occupy the 
Schneegruben, sufficiently testify,) renders it highly pro- 
bable, that this fossil also may belong to that formation ; 
and consequently dates its origin from a much more re- 
cent period than the foregoing species of this genus.* 
3. Tin . — This metal appears to be next in age to 
menachine. It is sometimes of nearly cotemporaneous 
origin with old primitive rocks. Thus it occurs in very 
old veins, that traverse granite, gneiss, mica-slate, and 
clay- slate. These veins contain, besides tin-stone, also 
wolfram, tungsten, molybdena, iron-glance, arsenic- py^ 
rites, copper-pyrites, topaz, quartz, mica, chlorite, apatite, 
fluorspar, steatite, and lithomarge. The veins that traverse 
clay- slate are accompanied with schorl, and appear to be- 
long to a different formation from those veins that occur 
in mica-slate, gneiss, or granite. 
It occurs also disseminated through granite, and in beds 
that alternate with strata of granite. This granite, how- 
ever, appears to belong to the newest formation. 
4. Scheele. —The two ores of this metal, viz. Wol- 
fram and Tungsten, are of equal antiquity with tin. JVol* 
frcim occurs almost always in veins in primitive moun- 
tains, along with tinstone; and sometimes, although 
rarely, ia veins in transition mountains.. It appears in all 
* Mitchell, Irish Transactions, 
