30 GEOLOGICAL MEMOIRS. 



Some of the veins of this group contain m the upper parts pre- 

 dominaurly iron-ores, as haematite, specular iron-ore, and hmonite, 

 forming the eisernen Hut of the miners. 



The veins of the pvi'itical lead-formation, above 300 in niunber, 

 appear rather younger than the noble quartz formation ; they every- 

 where intersect the porphyries. 



c. The nohle Lead-formation or Br ov:n-spar formation (the Brander 

 and the Scharfenberg and Drehbach formations of Freiesleben) occurs 

 with especial fi'equency in the veins south-west from Freiberg, near 

 Brand and Erbisdorf ; and in a more isolated manner in the district 

 of Scharfenberg and Drehbach. In the majority of cases the veins 

 of this formation appear partly with a strike from north to south 

 (flat veins), partly with a strike from north-east to south-west (as 

 vertical (stehende) and moiTnng veins), with a dip, often at a very 

 low angle, to the west and north-west. 



The average breadth of these veins, some of which have been fol- 

 lowed for more than 500 fathoms in length and 200 fathoms in depth, 

 varies from two to ten inches, but sometimes amounts to one fathom. 

 The mass filling them is especially characterized by dolomite (brown 

 spar), diallogite and quartz, in frequent combination with galena, 

 blende (both of them usually argentiferous), mispickel, pyrite, pyrrho- 

 tine, sHver-fahlore ; besides the following newer fonnations appear in 

 a more isolated manner in them : — siderite, calc-spar, opal, jasper, 

 baiytes, celesrine, fluor-spar, conite, nacrite, chalcopyiite, fahlore, 

 pyrargyrite, argentite, native silver, earthy sulphuret of silver, poly- 

 basite, stephanite, plumosite, haematite, stilpno siderite. The follow- 

 ing are very rare : freieslebenite, pyromorphite, cei-ussite, pechurane, 

 native arsenic, realgar, and kerate. These constituents of the veins 

 often show a simple, often a repeated symmetry, in this maimer, that 

 quartz with non-argentiferous galena, blende, mispickel and pyrite 

 form the outer (older) band, nearest the walls ; diallogite and dolo- 

 mite, or brown spar, with the above ores, but argentiferous, and also 

 silver-fahlore, the next following band ; and siderite, barytes, fluor- 

 spar, calc-spar, pyrargyrite, argentite and native silver, the inner 

 (newest) band. 



In regard to theh age, these veins come after those of the noble 

 quartz-fonnation, but pretty near or very httle after those of the py- 

 ritical lead-foiTQation. They intersect the porphyries. As yet about 

 340 more important veins are known, belonging to the brown-spar 

 formation. 



3. The Barytes, Silver and C oh alt group is the most widely ex- 

 tended and numerously represented group of veins in the Erzgebirge ; 

 for more than 1200 veins belonging to it are distributed over the 

 whole Erzgebirge, wherever its crystalline, massive and schistose rocks 

 extend. They are especially frequent and perfectly formed in the 

 vicinity of Freiberg, Marienberg, Anuaberg, Joachimsthal, Johann- 

 georgenstadt and Schneeberg. In their strike two chief directions 

 may be observed, namely from north-north-east to south-south-west, 

 and fr'om east-north-east to west-south-west. 



The mineralogical composition of these veins is remarkably variable, 

 and in some districts is altosether different from that in others. This 



