The small lithium-tin deposit Vernéřov presents an occurrence of phosphate pegmatite, which is fully unique in the whole Bohemian massif. Besides uncommon composition it differs from typical pegmatites by a small and constant thickness, absence of zoning and an intensive ore mineralization. The deposit is formed by a group of quartz-montebrasite-feldspar veins with sulphide- and cassiterite ore mineralization. The veins fill cracks in weakly migmatitized biotite paragneisses of the Smrčiny crystalline complex. They are steeply inclined, parallel ordered and they form so-called dyke swarm in the direction NE-SW, which is up to 30 m wide and about 1 km long. The main vein is less than one meter thick.
Vernéřov
Tin mining on SW slopes of the hill Na Pískách (the old German designation Zinnberg=”Tin Hill” was much more fitting) between Vernéřov and Horní Paseky operated most likely since mediaeval already. In written form is documented since 16th century. Initially alluvia and placers were panned, later shallow diggings were excavated. After a long pause, in the year 1954, geological survey of the deposit started. Due to small extent of the ore mineralization the works were stopped after four years. In the year 1996 the exploration pit has been newly secured, and major part of the adjacent dump pile was trucked away. Afterwards the locality was declared to a Natural Monument.
In the relict of the dump pile up to now occur abundant fragments of grey quartz, white potassium feldspar (microcline), and to feldspar similar, yellowish to greenish montebrasite. Into the three major minerals grow more phosphates, grains and aggregates of black-brown cassiterite and sphalerite, steel grey stannite, gold yellow chalcopyrite and other ore minerals of younger hydrothermal phase. In total more than 50 mineral species are listed from the locality.
Photo 1: Bell mill. Vernéřov Photo 2: Remains of tin mines. Vernéřov Photo: 3: The road to the medieval tin mines