The quarry in Zimnik is located within the granite massif of Strzegom-Sob\u00f3tka, which is part of the geological unit known as the Fore-Sudetic Block. The intrusive igneous rocks forming this massif occur in a relatively narrow belt (up to 12 km wide), stretching for almost 50 km from the north-western slopes of \u015al\u0119\u017ca to Jawor, where the belt narrows significantly. In this area, there are many granite quarries, with the largest ones located in the western part of the massif, between Strzegom and Paszowice. Within the massif, four varieties of granitoids are distinguished: hornblende-biotite granodiorites and biotite granites (mainly found in the western part of the massif) as well as two-mica granites and biotite granodiorites (occurring in the eastern part). In the Zimnik quarry, the most common rock variety of this massif was exploited, namely hornblende-biotite granodiorites. These rocks have a light gray colour and are primarily composed of feldspar, quartz, biotite, and subordinate amounts of hornblende. These minerals are visible to the naked eye and reach sizes of up to 0.5 cm, forming the background of the rock with a coarse- to medium-crystalline structure. Individual feldspar crystals are larger, reaching sizes of up to 2.5 cm. The coexistence of minerals with contrasting sizes is referred to as a porphyritic structure, and the minerals standing out in size from the background are called porphyrocrysts or phenocrysts. The largest grains are composed of feldspar, often with distinctive tabular shapes and well-defined cleavage surfaces, along which the mineral tends to preferentially fracture. Quartz, occurring in the form of gray aggregates, lacks cleavage and has a greasy luster. Individual biotite crystals have a tabular habit, but in this rock, they most commonly occur in the form of flattened aggregates of multiple sheets. Biotite is easily noticeable and recognizable as it has a black colour, distinct cleavage, and low hardness (it can be easily scratched with a steel blade). Hornblende can have a colour similar to biotite, but it is distinctly harder, and its crystals have a columnar shape. Tonalite is a subordinate rock variety. It is a rock that is distinctly darker and has a finer grain than the granodiorite described above. It contains significantly less quartz and more hornblende and biotite in its composition. At times, you can also encounter another rock variety, namely pegmatite. They occur in the form of veins or lenses primarily composed of quartz, feldspar, and biotite. What distinguishes them, however, is the size of the crystals, as they can reach dimensions of several or even a dozen centimetres. These rocks crystallize in the so-called post-magmatic stage, from residual melts left after the crystallization of the main rock types. They are of particular interest to mineral collectors because they often contain beautifully formed and rare minerals such as smoky quartz, fluorite, or stilbite.<\/p>\n
The age of these granitoids is estimated to be around 300 million years, which corresponds to the Carboniferous-Permian boundary. Indeed, it was a time of very intense magmatic activity in the area of present-day Lower Silesia. During the same time interval, granites intruded in the Karkonosze Mountains, and various volcanic activities took place, leaving their traces in areas like Wa\u0142brzych, Lubawka, and \u015awierzawa.<\/p>\n
Granitoids in this region have been extracted for centuries, especially intensively with the development of the Industrial Revolution. The first large-scale quarry in this area was opened in 1826 by Fryderyk Bartsch. Granite extraction in Zimnik also has a centuries-old tradition. In historical records, it can be found that in 1840, there were five quarries operating in that area.
\nGeomorphologically, Zimnik is located at the foothills of the Rogo\u017anica Hills, which are part of the Strzegom Hills range, characterized as isolated mountainous terrain in this region. The topography of this area is a result of uneven chemical weathering of granites and erosive removal of this material. The most intense process took place in the Paleogene period (66-23 million years ago).<\/p>\n","protected":false},"excerpt":{"rendered":"
The quarry in Zimnik is located within the granite massif of Strzegom-Sob\u00f3tka, which is part of the geological unit known as the Fore-Sudetic Block. The intrusive igneous rocks forming this massif occur in a relatively narrow belt (up to 12 km wide), stretching for almost 50 km from the north-western slopes of \u015al\u0119\u017ca to Jawor,…<\/p>\n","protected":false},"author":1,"featured_media":4881,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_seopress_robots_primary_cat":"32","_seopress_titles_title":"","_seopress_titles_desc":"","_seopress_robots_index":"","inline_featured_image":false,"footnotes":""},"categories":[71,74],"tags":[],"class_list":{"0":"post-6245","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-recommended-geosite","8":"category-slady-dawnego-gornictwa-i-hutnictwa"},"acf":[],"_links":{"self":[{"href":"https:\/\/www.gorykaczawskie.pl\/en\/wp-json\/wp\/v2\/posts\/6245","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.gorykaczawskie.pl\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.gorykaczawskie.pl\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.gorykaczawskie.pl\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.gorykaczawskie.pl\/en\/wp-json\/wp\/v2\/comments?post=6245"}],"version-history":[{"count":0,"href":"https:\/\/www.gorykaczawskie.pl\/en\/wp-json\/wp\/v2\/posts\/6245\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.gorykaczawskie.pl\/en\/wp-json\/wp\/v2\/media\/4881"}],"wp:attachment":[{"href":"https:\/\/www.gorykaczawskie.pl\/en\/wp-json\/wp\/v2\/media?parent=6245"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.gorykaczawskie.pl\/en\/wp-json\/wp\/v2\/categories?post=6245"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.gorykaczawskie.pl\/en\/wp-json\/wp\/v2\/tags?post=6245"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}