ORES OF COPPER 
93 
Ball and Shaler, ibid., ix, 1914, pp. 629-30, 632). They are 
interstratified with slates and dolomites. The beds in depth 
contain sulphides. The rich ores are mainly carbonates, 
especially malachite, and are secondary enrichments con- 
taining from 6 to 14 per cent. of copper. The original bedded 
Ores are pre-Paleozoic; the country has been lowered 
Probably thousands of feet by denudation, and ores from 
the rocks removed have been concentrated in the enrichments. 
BeppED OR SEDIMENTARY ORES — MANSFELD AND 
Micuigan — This group of copper ores has given rise to 
prolonged difference in interpretation. Red sandstones of 
different ages and countries are associated with copper ores, 
Which at Mansfeld in Germany have been worked since the 
year 1199.! That field has yielded 800,000 tons of copper and 
been the second largest copper-producing field in Europe. 
The area has been described as the birthplace of strati- 
graphical geology. The ore occurs in a Permian bituminous 
shale (the Kupferschiefer), which lies above the Lower 
Permian red sandstones, and below the Zechstein, a Middle 
Permian limestone. 
The average ore contains about 14 per cent. of copper, 
3nd occurs in three layers of a bed which is usually from 20 
to 24 inches thick ; but the ore may penetrate 4 inches into 
the Underlying sandstone. The bed is often traversed by 
faults which contain copper and cobalt. 
The great extent of the deposit—in the Mansfeld syncline 
alone 1t is 15 miles wide—suggested the origin of the copper 
ww Precipitation from the Permian sea. The bed contains 
0d plants and fossil fish of which the distorted shape, 
according to von Groddeck, was due to the agonies of copper 
Poisoning, but was probably caused by ordinary post-mortem 
shrinkage, According to the second theory, mainly supported 
y Beyschlag and Krusch, the copper was brought in solution 
JP the faults and precipitated in the shale by its organic 
Matter. The copper is present as grains and nests of chal- 
Ocite which ig usually, and bornite, which is often, secondary, 
and as later veins of chalcopyrite: the .ore has partly 
Tor the history of this field, cf. Dr. W. Hoffmann, Mansfeld, Gedenk- 
rift sum 725 Jaehrigon Bestchen des Mansfeld-Konzerns, 1200-1925, 
Be PP; Berlin, 1025. A recent description of the geology s given by 
. D, Trask, Zeop, Geol., xx, 1925, pp. 746-61.