Przygórze heap, Bolesław Mine, Przygórze, Gmina Nowa Ruda, Kłodzko County, Lower Silesian Voivodeship, Poland

A close-up of typical, glass-rich, vesicular, and multicolor coal-fire buchite - a type of pyrometamorphic rock usually formed in expense of sandstones are other, more fine-crystalline sedimentary rocks. The color zonation - resembling that sometimes seen in the brick formation process - comes from mineral zonation. The latter is a response to ...

© Łukasz Kruszewski 2019

An example of porcellanite - low-iron type of metapelite, a pyrometamorphic rock.

© Łukasz Kruszewski 2019

A close-up of pyrometamorphic breccia made of the dominant, red, hematite-rich buchite (with very characteristic nodular shape, clearly pronounced vesicular texture, and glassy luster), and some white porcellanite. Buchites are formed due to pyrometamorphism (contact metamorphism either in zones of fossil fuel fires or within some volcanic areas) ...

© Łukasz Kruszewski 2019

A full view of typical yellow metapelite which is either cut or cemented by veins of what looks like a typical greenish buchite. This specimen is a bit exceptional, as the typical vein-forming pyrometamorphic rock is parabasalts which otherwise seems to be absent in this specimen.

© Łukasz Kruszewski 2019

A close-up of the surface (with some undulations related to plant fossils) of once-typical black, coaly shale, which was later thermally and marginally transformed into yellow metapelite (metamudstone). The process of such transformation is pyrometamorphism. The process is fully natural: it occurs in the interior of a coal-mining waste (barren ...

© Łukasz Kruszewski 2019

A fragment of a pyrometamorphic breccia in its portion largely occupied by two varieties of buchite - the dominating dark red hematite-rich one, and hematite-low orange one. The latter type also bears some more light-coloured zones which characterize in an even smaller amount of iron. Minor orange-red shaly fragments are clinkers thermally fused ...

© Łukasz Kruszewski 2019

Full view of red clinker covered by secondary, relatively coarse-crystalline hematite. This hematite likely formed in course of a recrystallization process, while the fine-crystalline (often skeletal) hematite standing for a chromatophore for the main clinker mass is most likely derived from parent gas phase. The gas phase is an effect of coal and ...

© Łukasz Kruszewski 2019

This is a thin section of a mineralogically complex metacarbonate slag. Its high calcite content and absence of glass are the main clues to its non-parabasalt genesis. The clinopyroxene and gehlenite are localized in the greenish-yellow to brownish zones, calcite is filling the voids between other minerals or occur in veinlets. Beside the listed ...

© Łukasz Kruszewski 2019

Full view of a typical multi-colour buchite - a glassy, vesicular pyrometamorphic rock. Its greenish/green-gray and violet/purple-gray portions mark zones where iron remains in its reduced form. The green portions usually have it in form of hercynite, while the purple-gray ones - in form of indialite-ferroindialite with some cordierite-sekaninaite ...

© Łukasz Kruszewski 2019

Tiny Cr-bearing hercynite-spinel crystals (automorphic and skeletal ones) within glass of a metamudstone (metapelite). BSE (back-scattered electron) image: the information carried by this image is electron density; the more bright zones contain more heavy elements, in general. Picture taken during a microprobe session. The hercynite composition is ...

© Łukasz Kruszewski 2019

This is a BSE (back-scattered electron; this means the photo bears an electron density information: the bright zones are, in general, more rich in heavy elements than the dark ones) image of a thin section in a border zone between a metamudstones (metapelites) and a buchite. The dark phase is mainly glass, while the tiny bright skeletal crystals ...

© Łukasz Kruszewski 2019

Another example of calcite-rich accumulations covering a pyrometamorphic rock which in this case is a typical clinker (here: red base). This particular sample is interesting in containing small amount of tobermorite - a relatively rare Ca silicate. Such accumulations are likely derived from some hydrothermal veinlets cutting the local ...

© Łukasz Kruszewski 2019

BSE (back-scattered electron) image of nice, though tiny, hercynite crystals. It is not an accident to find these spinel-group species concentrated at the border between two lithologically different pyrometamorphic rocks: a metamudstone (a metapelite; to the left) and a parabasalt. Chemical zonation in some crystals - expressed as more bright ...

© Łukasz Kruszewski 2019

This is a boundary zone of typical red clinker (main components: quartz, mullite, fine-crystalline hematite) passing into a hematite-dominant "pod" which may represent an oxide-rich slag.

© Łukasz Kruszewski 2019

Cr-enriched needle-like mullite in glass of a buchite - a BSE (back-scattered electron image: more dark zones have heavy elements more concentrated) image from a thin section. The origin of the rock is to be debated - mullite is a typical component of buchites, but some artificial "rocks" may resemble natural buchites. The mullite has typically ...

© Łukasz Kruszewski 2019

Nice hematite crystals (bright phase in this BSE = back-scattered electron image; the higher brightness corresponds to larger relative concentration of heavy elements) within glass phase of parabasalt from a pyrometamorphic breccia. This hematite composition is (Fe1.76Al0.18Mg0.03Ti0.01Si0.01)Σ2.99O3.99 and it bears up to 0.15 wt.% CoO. Aluminium ...

© Łukasz Kruszewski 2019

This is a close-up of a complex microcrystalline mixture once constituting a thin veinlet (up to few cms in diameter) cutting the Przygórze heap pyrometamorphic complex. The veinlet composition suggests its hydrothermal origin. Manifestations of hydrothermal processes (often resembling the once-recognized pneumatolytic ones) in coal-fire zones ...

© Łukasz Kruszewski 2019

A BSE (back-scattered electron; this means the image shows variations in electron density: more bright zones concentrate, in general, more heavy elements) image from a thin section of a pyrometamorphic breccia showing elongated and relatively dark and large crystals of anorthite, with bright and somewhat chemically zoned crystals of spinel-group ...

© Łukasz Kruszewski 2019

A BSE (back-scattered electron) image from a thin section of a pyrometamorphic breccia taken in a zone of porcellanite (also known as white metapelite). As compared to other microprobe-session photos from this locality this one clearly shows that crystal sizes in porcellanites are smaller than in parabasalts. The BSE-bright (i.e., containing more ...

© Łukasz Kruszewski 2019

(At least) two generations of hematite: relatively coarse-crystalline, dark hematite residing on/in a clinker coloured red by fine-crystalline hematite. The first type of hematite most likely marks former (small) gas channels; it is not sure if this hematite is a recrystallization products but this is likely. The fine-crystalline hematite - the ...

© Łukasz Kruszewski 2019

Cr-enriched needle-like mullite in glass of a buchite - a BSE (back-scattered electron image: more dark zones have heavy elements more concentrated) image from a thin section. The origin of the rock is to be debated - mullite is a typical component of buchites, but some artificial "rocks" may resemble natural buchites. In this photo mullite ...

© Łukasz Kruszewski 2019

This is a close-up of a complex microcrystalline mixture once constituting a thin veinlet (up to few cms in diameter) cutting the Przygórze heap pyrometamorphic complex. The veinlet composition suggests its hydrothermal origin. Manifestations of hydrothermal processes (often resembling the once-recognized pneumatolytic ones) in coal-fire zones ...

© Łukasz Kruszewski 2019

Another example of calcite-rich accumulations covering a pyrometamorphic rock which in this case is a typical clinker (here: red base). This particular sample is interesting in containing small amount of tobermorite - a relatively rare Ca silicate. Such accumulations are likely derived from some hydrothermal veinlets cutting the local ...

© Łukasz Kruszewski 2019

Hydrothermal vein cutting a pyrometamorphic complex of the Przygórze heap. The vein is is filled with powdery aggregates of a complex mixture comprising calcium minerals: carbonates (mainly calcite), silicates (including tobermorite), and fluorides (fluorite). The photo was taken by Oliwia Grafka during my field research. The vein is currently ...

© Łukasz Kruszewski 2019

Red clinker in situ. The dark patches within this rock are portions where dark glass is concentrated. Such portions may reflect varying Eh conditions of the very dynamic environment of the burnout zone = a zone surrounding coal fire foci where pyrometamorphic transformations of primary sedimentary rocks coexisting with coal take place. This photo ...

© Łukasz Kruszewski 2019

Part of pyrometamorphic complex of the Przygórze heap. As in the case of most coal-fire zones, the main product of pyrometamorphism is red clinker - a type of rock formed due to baking and very partial melting (and glazing) of coaly shale protoliths, with preserved shaly structure. This particular complex also bears some other pyrometamorphic ...

© Łukasz Kruszewski 2019