Rare arsenates displace mimetite

In many cases, mimetite and cerussite are covered by younger, often crusty, finely crystalline or globular minerals and in some cases displaced as pseudo or paramorphic. In addition to goethite, these include above all linarite, malachite, brochantite, segnitite, cuproadamine and bayldonite. The copper-containing adamin (variety cuproadamin) has been known since the 1980s (MANDLER et al. 1989), which forms light-, olive- or apple-green spherical-kidney crusts and aggregates, some of which consist of tiny crystals, on mimetite and quartz. Cuproadamin can hardly be distinguished from its close relatives zinc olivenite and olivenite. Zinc olivenite, which is an independent link in the Adamin - olivite series with a Cu: Zn ratio in the range between 1: 3 and 3: 1, occurs in the form of green, shiny, spherical aggregates up to 0.5 mm (GRÖBNER & KOLITSCH 2009). The copper end link of this series, the olivite, was also found in the Schöne Aussicht mine. It forms small olive-green crystals that line turf-like cavities in the quartz.

Bayldonite is visually similar to cuproadamine, the color of which is usually a little darker green. It also forms green crystalline crusts that cover quartz, brown iron stone and mimetite. Intense yellow crystalline coatings and spherical aggregates have been found to be segnitite. They are composed of innumerable pointed rhombohedral crystals, are relatively common and sometimes form pseudomorphoses like older mimetite crystals. In the investigations with Raman spectroscopy and EDX, no sulfate content could be detected, so that the segnitite can be clearly differentiated from beudantite.

Scorodite, which we could not find ourselves, is mentioned as small crystals (ANONYMUS 1989). Instead, we were able to identify pharmacosiderite in tiny light yellow pseudo-cubic crystals.

What is special is that the pharmacosiderite from Grube Schöne Aussicht has significant lead contents that are close to the composition of plumbopharmacosiderite. Presumably there are intermediate mixed crystals between the two. It has not yet been possible to check whether there is also a zonal construction of the two minerals.

"Young savages" in the dump material

Very species-rich and with many rarities, a paragenesis emerges in the mineral stock of the Schöne Aussicht mine, which at least for the most part only arose in the heap material. For the heaps of lead-copper-zinc mines typical minerals with crystals are consistently in the micro range, as they have meanwhile been observed in many places. Anglesite and cerussite belong in small crystals. The cerussites rarely appear slightly bluish. Light yellow, almost transparent crystals of solid sulfur are occasionally found together with angelsite in the vicinity of corroded galena. Leadhillite and susannite occur as pseudo-hexagonal tabular crystals up to millimeter in size. Most of them are colorless to cloudy white, susannite is also described as yellowish (ANONYMUS 1989). As described by other sites, it can be assumed that here, too, at least some of the paramorphoses are from Susannite to Leadhillite. Leadhillite / Susannite are usually accompanied by caledonite. Due to its greenish-blue color, this is somewhat more conspicuous and forms long prismatic crystals, which are usually aggregated in the shape of sheaves and tufts. Covellin often shows up together with these minerals as blue-black metallic coatings and small flaky pustules on the weathering sulfides.

Basic copper sulfates are another typical representative of this mineral society. Langite and posnyakite were found quite frequently in the material from the Schöne Aussicht mine, they are light to ink blue in color and difficult to distinguish from one another. Langite crystals often show short prismatic, blocky and often six-sided shapes and reach a size of about 2 mm. Posnjakit appears in tabular, leafy, often diamond-shaped or pointed forms. As at other sites, transitions from langite or posnjakite to brochantite can be observed here, which manifest themselves in zonal to completely cloudy green colorations of the crystals. Brochantite itself forms emerald green tabular, partly tongue-shaped crystals and crystalline crusts. A mineral that has not been known for very long is redgillite. This occurs with preference in the company of Langit and / or Posnjakit. It is therefore not surprising that the fine, light-green and grass-green needles up to 1 mm in length could also be found in the heap material of the Schöne Aussicht mine (SCHNORRER et al. 2006). They are composed of tufts, pustules and sheaves that have always formed in the vicinity of chalcopyrite, which according to SCHNORRER et al. is almost always partially converted into bornite or chalcosine. Serpierite is used by SCHNORRER et al. named as an accompanying mineral of redgillite without further description. With Devillin, a closely related and chemically and visually very similar mineral could be detected in light turquoise-blue ledge-shaped crystals. This is also a redefinition for the site like ktenasite, which forms bluish-green tablets (<0.5 mm) and has a high nickel content. Both occur together with brochantite and linarite on quartz, brown iron ore and weathered lead and copper ores. Turquoise-green schulenbergite leaflets that have grown together to form small rosettes have been observed very rarely (GOLZE et al. 2012). Another very rare aluminum-containing copper sulphate is spangolite, which forms the characteristic pointed six-sided crystals (<0.5 mm) of blue-green color on a few finds. A very unusual mineral is that of MANDLER et al. (1989) described copper nitrate Gerhardtite, which forms apple-green, radially arranged tabular crystals up to 0.5 mm in size near weathered copper ores.

Globular malachite also occurs again as heaps. Rosasite is quite similar to this, but its spheres measuring only 0.2 mm have a rather blue-green color. MANDLER et al. (1989) were able to detect this copper-zinc carbonate by X-ray analysis. The rosasite beads grew up on cuproadamin. Intense light blue, radial-rayed spheres up to 0.5 mm in diameter, which sit together with cerussite, mimetesite and posnjakite on quartz, sphalerite and pale ore, turned out to be the very rare sulphate and arsenate-containing copper-zinc carbonate Claraite - a first find for the Siegerland. The white, needle-like crystal clusters of aragonite and the long-tabular, typically formed gypsum crystals measuring up to 3 mm were also formed as new formations in the heap material; also white scaly leaves of hydromuscovite ("sericite") on quartz. Amorphous smooth kidney crusts of blue-green color can be assigned to the allophane, which was already used by MANDLER et al. (1989). White, powdery interstitial fillings in quartz, siderite and greywacke made of kaolinite and / or dickite are quite common, but have not been investigated further.

The widely occurring nickel ores ullmannite, gersdorffite and millerite provided the material basis for the formation of a number of other minerals. Ullmannite crystals that have grown into quartz are occasionally completely or partially displaced by white, yellowish or greenish stibiconite, as has already been observed at other Siegerland sites (e.g. Grube Brüderbund; HENRICH 1996). Bottinoite is a characteristic decomposition product of Ullmannite in the dump material. The nickel-antimony hydroxide could also be found in the typical blue-green, translucent and mostly rounded-edge tablets (<0.5 mm) on the steps from the Schöne Aussicht mine. The weathering of the Gersdorffite resulted in annabergite in light green spherical-kidney-shaped aggregates. The closely related Köttigit forms rosette-like and cluster-like aggregated strip-shaped crystals. Both Annabergit and Köttigit show a clear copper content, which indicates a mixed crystal formation with Babánekite, which has not yet been dominant. Rare green pseudomorphoses after Millerite needles turned out to be the relatively rare nickel hydroxide sulfate jamborite. Comparable pseudomorphoses from other Siegerland sites were identified and described as morenosite more than two decades ago (HENRICH 1996; REINHARDT 1997).

When, in 2013, a similar historical stage by Pfannenberger Unity near Salchendorf in the collection of Harvard University (Cambrigde / Massachusetts, USA) was analyzed and published as jamborite (ALONSO-PEREZ & WARMINGTON 2013), the first doubts arose. In the case of the Schöne Aussicht mine, the jamborite has now been confirmed. The Raman spectrum fits well with jamborite, the EDX result with restrictions, since superficial impurities are presumably present. Such impurities could also have been the decisive factor in incorrect determination in the samples from the other Siegerland sites. A new review of these samples is still pending.

In summary, it can be said that the Schöne Aussicht mine near Burbach is one of the most species-rich sites in the Siegerland. There are still some question marks unanswered and it can be assumed that some collections still contain other species that are new to the site. Overall, through our own collections and with reference to the more recent literature, we were able to list 71 different mineral types for this site - including rarities such as bayldonite, bottinoite, claraite, gerhardtite, jamborite, ktenasite, redgillite or zinc olivenite.

Regarding the current find situation, it must be said that the heaps and outcrops in the area of ​​the Schöne Aussicht pit are now heavily searched and no longer very productive. No wonder, since the site was already intensively collected in the 1980s. With a lot of luck, however, some of the minerals described here can still be found in document quality on the heap of the upper adit, for example mimetesite, cerussite, langite and the ullmannite enclosed in quartz. Not far from the Schöne Aussicht pit, on the top of the castle hill, there was a Celtic hill fort from pre-Christian times, of which the remains of a ring wall can still be found in the forest. This old Keltenburg has nothing to do with the mine itself, but it gives the mountain its name. The sites not far away in Buchhellertal have also been heavily searched. However, all of the pits are located in a historically, scenic, mineralogically and geologically attractive area, in which both mining and long-extinct volcanism have left plenty of traces and outcrops that can be discovered on long hikes.