WEISSENBACH ON VEINS. 59 
~ The secretion-veins have furnished the author with the richest 
material for varied remarks. He understands by this veins and 
vein-masses (Gangtriimmer) which have had a chemical or crystalline 
origin, and are so enclosed in the firm wall-rock that the introduc- 
tion of their substance could not have taken place immediately or in 
open canals from without, but must have been effected by a secretion, 
or separation and collection of matter from the enclosmg rock in the 
immediate vicinity. It appears that in the formation of these secreted 
products, essential differences in mode of origin may exist, and con- 
sequently more numerous specific distinctions may be made among 
them than in the individual formations of the other classes of veins. 
In this class are distinguished : Plutonic secretion-veins, formed by 
collection of matter. Such secreted masses, formed predominantly 
of crystalline felspar or also of quartz, are especially common in the 
granites both of the Erzgebirge and the Penig-Mitweidaer Weiss- 
stein mountains, and also in the upper Lausitz. Indeed, generally 
speaking, a very felspathous, plutonic mountain-rock will not readily 
be found in which this phenomenon does not occur,—a result of the 
same forces which have caused the formation of the various species of 
minerals. Plutonic secretion-veins formed by the oozing out of matter 
into fissures (Ausschwitzung) : the distinction is pomted out between 
veins in plutonic rocks formed by the oozing out of matter into fis- 
sures, and the plutonic eruptive veins in the same rocks ;—the latter 
exhibit a more uniform structure through their whole mass, they 
are finer-grained than the rock in which they occur ; the former, on the 
contrary, show exclusively a perpendicular position of the individual 
crystalline parts composing them towards the walls of the veins, and a 
laminar disposition im the direction of the vein (Ganglagerstructur) ; 
they are coarser-grained than the rock im which they occur. To the 
most remarkable secretion-veins in plutonic rocks belong the Stock- 
scheider vein in the mines at Geyer, and in the Weisserdenzeche near 
Aue; the latter of which especially presents many very problematic 
phenomena. The closely-connected coarse crystalline deposits of tin 
at Zinnwald are referred to the class of mineral veins, and conse- 
quently not minutely described. 
Veins in serpentine appear as secretion-veins, without any previous 
open fissure ;—minute cracks caused by contraction may have first 
occasioned the present vein-like separations. On the margin they 
consist of noble serpentine (picrolite), in the middle of schillerspar. 
Grains and small roundish masses, in which the two mimerals are 
united in a similar manner, occur in the rock between and near to 
these veins. 
The veins in the serpentine of Waldheim, which are filled with 
chlorite, chlorite-earth, picrolite, asbestiform steatite, and a little 
mica or tale, traverse, with very even and easily separable sides 
(Saalbiénder), the beds, or lie in the numerous division-planes like 
very thin intermediate strata. As these have occasioned dislocations, 
their true character as fissures cannot be doubted. 
Masses and nests of quartz in slates, as in clay-slate, mica-slate and 
gneiss, are very numerous and common, but not the less remarkable, 
