Commune: Ząbkowice Śląskie (pow. ząbkowicki, woj. dolnośląskie)
Framework element or context represented:
Representative of Cenozoic weathering mantles developed over basement rocks in Central European uplands; mineralogy of ultrabasic rocks and their metamorphosed and weathered derivatives.
Primary geological/geomorphological interest:
Thick residual weathering mantle on serpentinite, unique suite of layer silicate minerals.
Comparative assessment justification:
The Szklary site is an exceptional locality as rare outcrops of deeply weathered rock in Central Europe and a unique diversity of minerals over a relatively small area. They are present in many museum collections around the world are used as reference samples in mineralogical studies.
Protection status and accessibility:
Currently no special protection status.
Character of site: Abandoned open-cast mine.
Area: 100 ha
Altitude: 320-370 m a.s.l.
Lithology: other metamorphic rocks, hydrotermal veins, other sedimentary rocks
Discipline: Mineralogy, Geology of mineral deposits
Process Age: Neogene, Paleogene, *all periods
Bedrock Age: Permian, Carboniferous, Devonian, Silurian, Ordovician, Cambrian, *all periods
Description of primary interest:
The Szklary Massif is an Early Palaeozoic serpentinite body located within the Niemcza dislocation zone, highly and deeply weathered in its near-surface part. The thickness of the weathering mantle is variable and reaches from a few to more than 70 m, changing significantly over very short distances. In the former mine walls the co-existence of relatively fresh serpentinite and its highly altered equivalents can be observed. Weathering is considered lateritic, although an uppermost ferruginous horizon is absent. Hydrothermal activity preceded the weathering stage, which is most likely of Palaeogene age. Altered serpentinites contain a suite of secondary minerals of complex origin, including some identified in Szklary for the first time in the world, which documents a complicated geological history of the massif. Among the most significant minerals are Ni-corrensite, interstratified kerolite-stevensite, interstratified serpentine-smectite, kerolite-pimelite and clintonite. In addition, chryzoprasm, chalcedony and opal occur in abundance. The Ni-bearing weathering mantle used to be mined for nickle ores, whose concentration was up to 2.5%, but the mine was eventually closed in the 1980s. The former mining area includes several pits of variable lenght and depth, interspersed with waste heaps. The majority of pit walls are now covered by talus.
Literature:
DUBIŃSKA E., SAKHAROV B.A., KAPROŃ G., BYLINA P., KOZUBOWSKI J.A. 2000–Layer silicates from Szklary (Lower Silesia): from ocean floor metamorphism to continental chemical weathering. Geol. Sudetica 33(2): 85-106. NIŚKIEWICZ J. 1967–Geological structure of the Szkalry Massif (Lower Silesia) (English sum.). Rocznik PTG 37: 387-416. NIŚKIEWICZ J. 2000–The Szklary Massif nickle-bearing weathering cover (English sum.). Geol. Sudetica 33(2): 107-130. OSTROWICKI B. 1965–Nickel minerals of the weathering zone of serpentinites at Szklary (Lower Silesia) (English sum.). Prace Mineralogiczne PAN 1: 1-92.