Wittichen Mining District

General

Wittichen is a small village 5 km to the north of Schenkenzell (upper Kinzig Valley), 30 km south of Freudenstadt.

Wittichen today consists of a convent church (open to visitors), a convent museum and about 30 houses.

History

Wittichen had been founded in 12th century by a nun, St. Luitgardis. Mining is supposed to be started in those times, but there are no old records (any more?) confirminin mining in high medieval times.

The mines were first mentioned in 1517, when a mine near the convent church of Wittichen ("Bergwerk by dem Gotzhus Wittechen", according to Bliedtner and Martin, 1986) was lend to a citizen of Wolfach. A mining regulation enacted November 12th, 1529 can be seen as direct evidence of mining in this period, as "ore colours" are mentioned. Those seem to have been secondary minerals, copper secondaries most likely. The procedure of colour production from the cobalt arsenides remained unknown until 1540, when it has been discovered in Saxony. The first cobalt pigments at Wittichen were produced in 1703. Until then, silver had been the only ore mineral mined.

Rich findings of native silver led to mining activities to the north and northwest of the convent. Wittichen hab been by far the most important silver mining district in the Central Black Forest. About 6 tons of silver had been mined until 1856.

In 1817 the mine inspector SELB  reported the occurrence of secondary uranium minerals from Sophia Mine, later on (1840) DE MARIGNAC reported the occurrence of pitchblende from the same mine. The old miners had already known pitchblende as "bleyschwere schwarze Ertz-Arth" (black kind of ore, heavy as lead) or "eisenartiger wilter Kobolt" (iron-like wild cobalt). In contrary to other similiar mining districts like Schneeberg in Saxony or Jáchymov in Bohemia (today Czech Republic) no uranium mining period to produce yellow glass colours followed.

In 1911-14 and 1918-22 prospection on radium took place, not leading to mining activities.

Due to the high need for uranium ore in cold war uranium prospection in the Black Forest took place intensely. In the Wittichen area uranium prospection has been done in the 1950'ies and '60ies under direction of the President of the Geological Survey of the Federal State Baden Württemberg, Prof. KIRCHHEIMER. The prospection led to the result that mining on uranium is not profitable.

The actual size of the Wittichen district is somewhat debatable. If we consider all similiar vein mineralizations as belonging to the  mining district, one can roughly put the outer borders as following: Alpirsbach-Schramberg-Schiltach-Reinerzau.

But this is incorrect due to the territorial splitting until 19th century.

While Wittichen, Vortal and Schenkenzell  belonged to the Principality of Fürstenberg (later on the Grand Duchy of Baden), Alpirsbach and Schiltach belonged to Württemberg.

From this point of view there cannot be one single Mining District.

I will divide the mineralizations in the upper Kinzig valley into 4 parts, describing Wittichen at this page, Schiltach, Alpirsbach and Reinerzau will be discussed at other pages (not in planning for now).

Mine Menu

Choose a sublocality in the Wittichen district from the list below!

The two main localities are the Schmiedestollenhalde (see Gnade Gottes mine) and Sophia mine. If you are looking for specific mines in the area to compare your specimen with, check out those two, about 80 percent of all specimens from Wittichen are from those two localities!

Geology

The Wittichen district with its adjoining districts (Alpirsbach, Reinerzau, Schiltach) is situated in the northeasternmost part of the largest granite intrusion, the hercynean Triberg granite. It is surrounded by gneisses. Granites and gneisses usually are covered by sedimentary rocks (upper permean to lower triassic arcoses and sandstones). In the valleys those are eroded, the crystalline rocks are outcropping.

The Triberg Granite is a hercynean late orogenic granite body with heterogenous composition, mostly consisting of biotite granites, leucogranites to -tonalites and -diorites (poor in mafic minerals such as amphibole or biotite), granodiorites. In the Wittichen district biotite granites are most common. The rock does consist of quartz, K-feldspar, plagioclase and biotite.

The gneisses usually are biotite-rich dark types with abundant leucosomes (quartz + feldspar) in the range of cm. In some types garnet and cordierite do occur. Those garnet-cordierite-bearing types are metapelites and are named after the Kinzig river as kinzigites. The "type locality" is a small outcrop to the west of the road from Schenkenzell to Wittichen in the Little Kinzig valley. Graphite is a common accessory phase.

Sedimentary cover
According to BLIEDNER and MARTIN (1986) the upper permean to lower triassic sedimentary cover has an average thickness of 150 m and consists of sandstones

Carnelian dolomite
Thickness: 12 m
Consists of upper permian dolomite with countless veins of red carnelian to jasper (former algae biofilms), especially concentrated in the upper part

Tigersandstein (tiger sandstone) lower triassic (lower Bunter Sandstone)
Thickness: 20 m
Yellowish brown (due to limonite) or light grey sandstone with clay lenses and black spots of manganese oxides (former manganese carbonates)

Lower or ECK Conglomerate, lower triassic (Bunter Sandstone)
Thickness 40 m
Fine-grained, red sandstones with evenly included pebbles of quartz, petrified wood, porphyries, granites and rarely gneisses, hazelnut-sized in the average.

Bausandstein, lower triassic (Bunter Sandstone)
Thickness 40 m
Fine-grained massive red sandstone with ripplemarks and clay layers

Upper or Main Conglomerate, lower triassic (Bunter Sandstone)
Thickness 50 m
Forming the tops of the mountains surrounding the valley, similiar to previous unit, pebbles are hazelnut- to fist-sized. Pebble-free layers alternating with Conglomerates.

Vein mineralization usually only does occur in the granite. The veins usually do not extend into the gneiss, but sometimes the upper parts are extending into the sedimentary cover. This is proof that vein mineralization has occurred after the hercynean event.

Around the veins the granite usually is decomposed and hydrothermally altered. Plagioclase has been altered to clay minerals or sericite (with hematite usually being present), the biotite has been changed into chlorite + titanium minerals (usually rutile or anatase).

Those alteration zones can reach up to several meters from the vein and are irregular in spatial and vertical extension. Around the more productive zones (those are mostly the thinnest parts of the veins) the alteration is most widespread. One can see it as a type of hydrothermal alteration system in a granite body with veins lining fracture zones within. In those heavily alterated zones, native Silver can be found in the granite, even several meters apart from the vein. In former times the alterated granite had been mined as a silver ore!

Vein mineralization

The veins in the Wittichen district can be seen as hydrothermal infills of cooling fractures within the uppermost part of a granite body.

Three kinds of vein systems can be distinguished:

1. NNE-SSW veins

Those are the most important veins to the ancient miners.

The mineralization is uniform with quartz, baryte, Ag-Bi-Co-(Ni)-U ores. Carbonates (dolomite, calcite, siderite) and fluorite are less common and often restricted to single veins and/or parts therein.

The mineralization usually starts with quartz I, occurring in the rim zone in contact to the granite. Heavily alterated zones (clay bands) between quartz I and the host rock can be present, but often there is direct contact. Quartz can also occur as chert, which is often brecciated.

The subsequent mineral is baryte, occurring in two types:

a) red baryte with hematite inclusions

b) white baryte

Both types can be ore-bearing. At the stockpiles, white barites are usually more pleasing regarding ore mineralization.

Of the ore minerals, cobalt ores generally are most abundant, skutterudite and safflorite being the ore minerals. Nickel ores are far less abundant (ratio Ni:Co about 1:9). Nickeline and Ni-skutterudite are the Ni ores and usually are very rare. Ni-skutterudite occurs as intergrowth with skutterudite (growth zones in zoned crystals can often be seen even under the scope).

Silver is common, 6 tons of silver had been found at Wittichen. Amongst the silver ores, native silver is the most common one, followed by acanthite and proustite. Rare silver minerals are arsenpolybasite and xantoconite.

Arsenic usually is bound to cobalt arsenides. In despite to the Bi-Co-Ni deposits of Saxony, native arsenic is very rare and does only occur as small grains or aggregates, larger botryoidal aggregattes are not known.

Bismuth is a common component of ores, usually occurring as native bismuth. Bismuthinite is another common Bi mineral. Typical of Wittichen and rather uncommon of other Bi-Co-Ni deposits is the strong affinity of bismuth to copper, leading to emplectite and wittichenite. Of the latter Wittichen is the type locality.

In the upper part of some veins, copper bismuth sulphides are the most common ore minerals.

Uranium does occur as uraninite, often forming earthy, grainy to botryoidal pitchblende aggregates.

In the uppermost part of the veins, silver and/or Cu-Bi sulphides are concentrated, then a cobalt zone followed, uranium prefers the lowermost part. But there is no "uranium level" such as in the Erzgebirge Mts. of Saxony. Detailed studies during the second half of the 20th century have proven that the veins generally become thinner and less mineralized towards depth.

2. Cleft zones

Usually clay-filled fractures within the granite, often intersecting and dislocating the vein zones. Sometimes clefts are slightly mineralized. Then, they were also mined.

3. E-W veins

Those are baryte-quartz veins with Cu-Bi sulphides. There is only one E-W vein that had been mined to some extent for Cu and Bi, the Daniel vein. 

Mines in the Wittichen district

There are quite a lot of mine names in the district. Of those mines, only a few had some importance. Amongst those are only four, which had been of importance above local scale: Sophia, Alt St. Joseph, Neuglück and Gnade Gottes mine. Johann, Güte Gottes, Simson, Daniel and König David mines had been of some importance. The other ones only had been small exploration mines, following slightly mineralized clefts or veins with poor ore mineralization.

Outstanding amongst the mines important to collectors are the Sophia and Gnade Gottes mines, followed by Neuglück and Daniel mines (both being type locality for wittichenite), and Johann mine.

Simson and Güte Gottes mines are nearly unaccessible to collectors, even their stockpiles. Some of the others are accessible but with insignificant mineralization to most of the collectors. 

Mineral Paragenesis

In Wittichen 4 general types of mineral paragenesis can be distinguished:

1. Primary Bi-Co-(Ni)-Ag-U mineralization of the NNE-SSW veins

2. Primary Cu-Bi mineralization of the E-W veins

3. Secondary mineralization

4. Supergene mineralization in adits/shafts

 Table: Common minerals in the different mineralization types and their abundance

(+++ large amounts ++ very common, + common, o in some parts /veins in larger amounts, - small amounts, -- nearly none --- none at all

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