COTTA LIMESTONES IN CRYSTALLINE SCHISTS. 17 



is for the most part fine, white, and crystallo-granular, somewhat rich 

 in magnesia, and at many places a true dolomite. As accessory ingre- 

 dients, it contains Tremolite, Garnet, Talc, Serpentine (at Thiersheim), 

 Fluor-spar, and Graphite. At Gopfersgriin the mica-schist bordering 

 on the limestone contains Idocrase. Perhaps the south-west continua- 

 tion of this bed is represented by a kind of [Erlanfels] in the mica- 

 schist beyond the Fichtelgebirg granite. 



We evidently have here to do with a large mass which for a long 

 time has consisted of a combination of granular limestone, dolomite, 

 and spathose iron, the last of which has been converted into brown 

 iron-ore. May we not regard this whole group of intimately com- 

 bined rock-substances to have originally consisted of clay-slate vdth 

 thick beds of limestone, partly dolomitic, and of carbonate of iron, 

 such as very often occur together in the coal-formation ? The mica- 

 schist has resulted from the clay-slate, marble from the thick lime- 

 stones, spathose iron from the sphserosiderite, and at a later period by 

 a diiferent kind of change, the brown-ore from the spathose iron. 



At Stemmas, not far from Thiersheim, the limestone is distinctly 

 penetrated by numerous granite veins ; hence it appears that the great 

 Fichtelgebirg granite district bordering on the mica-schist to the 

 north is altogether of a later origin than the mica-schist with its in- 

 cluded beds, and also that perhaps it had a share as a cause or pro- 

 moter in the metamorphosis of the whole. 



Limestones of the district of Schwarzenberg in Saxony. — In the 

 mica-schist at Schwarzenberg occur a great number of granular lime- 

 stones and dolomite that have long been used as fluxes by the iron- 

 smelters, and termed " Flosslager." These so-called beds (as I 

 formerly noticed in my ' Explanation of the Geological Map of 

 Saxony,' part 2. p. 343) are not true layers, but flat masses, 

 forming veins and occupying fissures, which run nearly parallel with 

 the direction of the lamination, — sometimes contain fragments of 

 neighbouring rocks, or, cutting through the lamination of the mica- 

 schist, form ramifications, and at no place exhibit those numerous 

 alternations along the contact-surfaces, as we observed at Tharand 

 and Zaunhaus ; but on the contrary they have nearly always a clearly 

 defined line of demarcation above and below. These limestones are 

 very often accompanied with beds of ore, which lie in the mica- slate 

 in a position quite analogous to that of the limestones, and the rela- 

 tion of contact-formations and including rock is preserved throughout. 

 The ores form immediately either the bottom or the top of the lime- 

 stone, and are remarkable for their richness in various minerals : 

 they have supplied — Hornblende, Actinolite, Chlorite, Garnet, Ve- 

 suvian, AUochroit, Konpholite, Peponite, Sahlite, Pistacite, Mica, 

 Talc, Picrolite, Tremolite, Serpentine, Steatite, Felspar, Diopside, 

 Zoisite, Helvine, Axinite, Prase, Magnetic iron. Magnetic pyrites. 

 Iron pyrites. Copper pyrites, Arsenious pyrites, black and brown 

 Blende, Lead glance. Tin ore, Scorodite, Arseniate of iron, Calc-spar, 

 Barytes, Fluor spar. Bitter spar. Gypsum, Metaxite, Cerolite, Mo- 

 lybdenum, white and green Lead ore, &c., which must certainly have 

 come into existence iinder different conditions and at different times. 



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