2. Greywacke. Greywacke and clay slate are by far the most abundant rocks in the Hartz. It sometimes con tains glance coal, (blind coal,) and mineral pitch; and occasionally petrifactions of species of the genera by steriolites, and trochites.
3. Clay-slate. This rock is distinctly stratified, and some times occurs in elliptical and globular concretions, which have a concentric lamellar structure. It alternates with greywacke, and both rest on the primitive rocks already described.
Both greywacke and clay slate contain very considerable metalliferous formations. The following are the prin cipal ones.
a. A very thick bed of copper pyrites, iron pyrites, ga lena or lead glance, and brown blende, with compact heavy spar, and a very small quantity of quartz, and calcareous spar.
b. Veins of galena or lead glance, of which the follow ing formations have been ascertained.
a. Galena, associated with much calcareous spar, and splintery quartz, and small portions of iron pyrites, sparry iron stone, grey copper ore, and brown spar.
p. Galena, associated with sparry iron stone, calcare ous spar, heavy spar, and quartz ; with a minute portion of grey copper ore, brown blende, iron py rites, and copper pyrites.
y. Galena, with splintery quartz, and a smaller por tion of calcareous spar, sparry iron stone, iron py rites, and copper pyrites. In the upper parts of the veins, the calcareous spar is sometimes dissolv ed and carried away. The galena, or lead glance, is converted into white, black, and earthy lead ores ; by the decomposition of the copper and iron pyrites, there are formed varieties of ochry brown iron stone, malachite, azure copper ore, and copper green, and by the decomposition of the sparry iron stone, compact and fibrous brown iron stones, and ores of manganese.
.3`. Galena, with much brown blende, splintery quartz, and calcareous spar ; and occasionally small por tions of copper and iron pyrites.
E. Galena, with amethyst, large foliated calcareous spar, copper pyrites, and brown blende.
c. Veins of copper ore, which are distributed in the following formations.
a. The principal vein-stone, of the veins of this for mation is quartz, which occurs in such quantity as occasionally to fill up the veins from side to side.
It is in granular concretions, which are so loosely aggregated, that they can be separated by the mere pressure of the finger ; hence in mines in this for mation the quartz is dug out by shovels. This con dition of the quartz in these veins spews us the possibility of sandstone, and even of sand, being in many cases original chemical formations, and not mechanical deposites. The ores associated with the quartz are copper pyrites, malachite, copper green, copper black, tile ore, and brown iron stone. There sometimes occur, embedded in the loose sandy quartz, blocks of compact quartz, also por tions of heavy spar, and small strings of brown spar, and red iron stone ; and rarely fluor spar.
This formation consists of azure copper ore, and copper-green, with much fluor spar, and some times small portions of brown spar, and red iron stone.
v. Copper pyrites, and splintery quartz, with small portions of calcareous spar, iron pyrites, and galena or lead glance, are minerals of this formation.
d. Veins of iron-stone, of which the following forma tions are known to the miners.
a. Red hematite, and heavy spar.
p. Compact red iron-stone, with much calcareous spar.
y. Compact red iron-stone, with much quartz, and a small portion of iron flint.
d. Compact, fibrous, scaly, and ochry red iron-stone, with specular iron ore or iron glance, and quartz, and calcareous spar.
44 Sparry iron-stone in the lower part of the veins, but brown iron-stone in the upper parts.
e. Veins of manganese occur hut rarely ; and of this metal the only formation in the Hartz is that in which compact grey manganese ore is associated with heavy spar.
4. Whet slate. This mineral occurs in thin beds in the clay slate.
5. Alum slate. It occurs in beds in clay slate.
6. Transition flinty slate. It occurs in beds in grey wacke and clay slate. It passes into clay slate ; and in the mountains of the Hartz we find all the intermediate va rieties between perfect flinty slate, and well character ised clay slate. It is worthy of remark, that this mine ral, which, according to the Huttonian view, must have been in a state of fusion, occurs inclosed in clay slate, and exhibiting the gradation we have just mentioned.