In the regional geological setting, the Hämmerlein-Tellerhäuser and Breitenbrunn deposits belong to the Saxothuringian unit of the Fichtelgebirge-Erzgebirge anticlinal zone in the Western Erzgebirge. The wall rocks of the deposits are Cambro-Ordovician metasediments consisting of phyllites and various mica-schist and gneiss varieties with intercalations of so-called "colourful" rock series of carbonates, quartzites, quartzite schists, amphibolites and skarns (Grießbach sequence). The degree of metamorphism of the metasediments ranges from greenschist to almandine-amphibolite facies.
The main tectonic element of the region is the Gera-Jachymov Deep Fault Zone striking NW-SE, which is an important metallogenetic element for the Western Erzgebirge. The deposits are strongly influenced by this fault zone. West of the deposits the Eibenstock-Neudecker granite massif is exposed. This intrusive complex continues in the subsurface of the deposits at a depth of 150 to 1,000 m.
The interaction of the existing geological conditions is essential for the genesis of deposits. The granite was the source of the ore-forming fluids, the extensive faulting served as a migration path and the carbonate-bearing layers of the "colourful" rock series served as a chemical barrier for the recrystallization of the ore minerals.
Geological Characterisation of the Deposits
In the Hämmerlein-Tellerhäuser ore-field, there are three prospective ore seams: the Hämmerlein seam, which forms the Hämmerlein deposit, and the Zweibach and Dreiberg seams as the Tellerhäuser deposit. The horizontal extent of the ore contour is approx. 5.5 km x 1.5 to 2 km. The Hämmerlein and Dreiberg seams overlap for approx. 1.5 km at different altitudes. The general dip of the ore units is 10 to 15° SE at a vertical extension of +650 m to 0 m above sea level. The surface rock has a thickness of 150 m in Hämmerlein and reaches a maximum of about 800 m in Tellerhäuser.
The skarn body is composed of pyroxene, garnet, amphibole and magnetite skarn sequences with irregular distribution of sulphide and cassiterite mineralisation.
There are two types of ore in the deposit area: skarn ore, as the dominant type (tin, zinc, iron, indium) and schist ore as a carrier of tin-greisen mineralisation.
|The skarn ore has an average thickness of 2-3 m. Sulphide, magnetite and amphibol-chlorite skarns are the valuable skarn types. Varieties rich in garnet and pyroxene show no economic mineralisation. The most important ore minerals are cassiterite, sphalerite, magnetite and indium-rich chalcopyrite (through sphalerite inclusions <50 µm), as well as roquesite. The cassiterite occurs in typical association with quartz, fluorite and chlorite.|
|The schist ore is mainly formed at the horizontal contact of the skarns, but also forms independent ore lenses at a greater distance from the skarn. According to SDAG Wismut the largest schist ore body has an extension of 280 x 120 x 50 m. This type of ore is a quartz-muscovite feldspar schist, which is intersected discordant to the schist surface (10 - 15 °) by greisen-like quartz-cassiterite (fluorite-tourmaline topaz) veins.|
Resource estimation of the Hämmerlein-Tellerhäuser deposit according to JORC standard
|Ore [Mio. t]||3,1||1,1||4,2|
|Ore [Mio. t]||2,4||0,8||3,3|
|Ore [Mio. t]||1,3||9,4||10,7|
|Ore [Mio. t]||3,9||3,9|
|Ore [Mio. t]||6,9||15,2||22,1|
- There is further potential for by-products in the elements copper, silver and bismuth.
The Breitenbrunn deposit is located southwest of Schwarzenberg between the valleys of the Schwarzwasser and Pöhlwasser rivers. It extends for about four kilometres in strike and consists of four skarn seams, which are from west to east the St. Christoph (including Margarethe seam and Christoph Hoffnung seam), Fortuna and St. Richard seam. In the southeastern extension of the Christoph Hoffnung seam there is another unnamed skarn seam, which was drill tested by SDAG Wismut in the 1970s. This skarn seam is the subject of further exploration work carried out by Saxore Bergbau GmbH and is currently at an early stage of exploration.
An detailed deposit contour is only available for the Christoph and Christoph Hoffnung seam, which was explored by GFE in the 1960s. These deposits are not part of further exploration work by Saxore Bergbau GmbH. The skarn seams form two 15° to 25° SW-trending concordant units and are proven to be 1,200 m in strike and 700 to 800 m in dip almost continuously between surface and granite. The thickness of the meta-rock above the skarn deposit is almost constant at about 100 m in the deposit area, as the skarn deposits are dipping parallel to the slope of the Schwarzwasser valley.
Resource Estimation of the Breitenbrunn Deposit According to GFE and SDAG Wismut
Resource estimates for the "Iron Breitenbrunn" project based on the exploration work of GFE
|Ore tonnage [t]||Content [%]||Metal content [t]|
Resource estimates from the SDAG Wismut exploration
|Ore tonnage [Mio t.]||Content [%]||Metal content [t]|