GEOGNOSY AND GEOLOGY. 159 
limestone. Accompanying species are clay masses, gypsum, karstenite, 
and reck salt. Where the group is complete, two subdivisions may 
be distinguished. 
The lower division is strikingly characterized by the copper slate, a 
bituminous marl slate impregnated with copper ores. The proportion of 
copper is generally smail, from one to four per cent. The ores are finely 
disseminated, rarely collected in mass; they consist of copper pyrites, 
glance copper, grey copper, iron pyrites, zincblende, arsenical cobalt, and 
molybdenum glance. From the decomposition of these minerals, various 
metallic salts, as verdigris and mountain blue, are produced. The strata of 
copper slate are not generally thick; from one to two, rarely three feet. 
The thinness of the strata renders it a very laborious matter to mine the 
copper, the workmen being obliged to lie upon the side or back while 
extracting the ores. Fossil remains, especially of fishes, abound, owing 
perhaps to the fact that the great proportion of bitumen has facilitated 
preservation. 
Upon this copper slate rests a foetid marl, intermediate between copper 
slate and zechstein. The thickness of the bed varies from four to eight feet. 
Next comes the zechstein, a bituminous, marly, compact limestone, of brittle 
fracture, containing clay concretions and drusy cavities. It includes 
subordinate masses of gypsum, lithomarge, and copper ores, the latter 
accompanied by the usual salts of copper. The stratification of the 
zechstein is very distinct, and the rock is traversed by a doubly-rectangulaa 
cleavage. | 
The upper division is exceedingly complicated, and thus difficult of 
recognition, especially as the petrographical character of the rock species is 
subject to many modifications, and varies in different localities. For this 
reason there are many equivalents or representatives. The principal 
species occur in the following manner : 
First, rauhkalk (rough limestone), which, when in normal position, rests 
on the zechstein. It derives this well-deserved name from the roughness of 
its exterior. Its rocks are generally full of cavities, and, in some places, 
contain large caves. Such are the Liebensteimer in Thuringia, the 
Schwartzfelder and the Steinkirche on the southern border of the Hartz. 
The rough limestone is sometimes represented by feetid and magnesian 
limestones, which are apt to incline to magnesian and fetid marls; the 
drusy cavities are sometimes clothed with rhombohedrons of magnesian 
spar. The colors vary from grey to white, and its cleavage is not regular. 
In the caves occurring in this rock tertiary deposits are found, containing 
bones cemented by stalagmite. Fossil remains are limited to single beds. 
Next to the rough limestone comes the asche, an earthy foetid marl of 
ash-grey color, much darker when wet than dry, and non-fossiliferous. 
Then comes the fcetid limestone, which is extensively distributed in the 
compact form, and is found in thick beds; the sheity, oolitic, spathic, and 
breccious varieties are restricted to small districts. Zechstein and fetid 
limestone are closely allied, especially when the latter is in large masses. 
The bitumen which is diffused in feetid limestone is often concentrated in 
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