Minerals of Pohorje marbles

Abstract

Metamorphism of relatively pure limestone and dolomite yields generally marble and dolomarble (Best, 2007). Impure carbonate protoliths that contain variable amounts of quartz grains and shaly material may include, in addition to calcite, dolomite and quartz, as well as diopside, tremolite, talc, phlogopite, wollastonite, calcic plagioclase, vesuvianite, forsterite and grossularandradite (Best, 2007). Therefore, the presence of the minor content of non-carbonate minerals corresponds to the chemistry and mineralogy of the protolith and its metamorphic history. Mineral IntroductionThe thick Pohorje forests still hide many interesting mineral associations. This is also the case of Pohorje marbles. Thanks to various collectors, particularly Viljem Podgor{ek and Franci Golob, who carried out extensive field sampling, we have been given an opportunity to analyse the macroscopically visible crystals in the marble. The Pohorje marbles, which were highly esteemed already by the Romans, have thus been supplemented by some new minerals, which may contribute to the characterization of this rock. Minerals of Pohorje marbles Minerali pohorskih marmorjev Izvle~ekNa Pohorju izdanjajo pretežno kalcitni marmorji, ki ponekod prehajajo v dolomitne. Karbonatne kamnine, iz katerih so nastali, so vsebovale tudi detriti~ne minerale, ki so se med metamorfozo ohranili ali pa pre{li v nove minerale. Raziskali smo minerale v marmorjih s Pohorja, ki so kot kristali vidni s prostim o~esom ali z lupo 10 x pove~ave in s pomo~jo binokularnega mikroskopa. Z ramansko mikrospektroskopijo, SEM-EDS analizo in na osnovi morfolo{kih zna~ilnosti smo dolo~ili 17 razli~nih mineralov, med katerimi so, poleg kalcita, najpogostej{i in obenem tudi najbolj zna~ilni tremolit, diopsid, grosular in epidot. Prvi~ sta v pohorskih marmorjih opisana vezuvianit in skapolit. Ploskovno bogati so kristali kremena, ki vsebujejo igli~aste vklju~ke amfibola. Drugi minerali, ki dopolnjujejo mineralno paragenezo marmorjev, so razli~ni minerali sljud, minerali kloritove skupine, glinenci, magnetit, titanit, pirit in grafit. Dolo~ena mineralna združba nam razkriva mineralno pestrost pohorskih marmorjev in nam ponuja nove izzive za raziskovanje zna~ilnosti in razmer pri nastanku te plemenite kamnine, ki so jo cenili in izkori{~ali že Rimljani, danes pa ponovno dobiva svojo veljavo in prepoznavnost. AbstractIn the Pohorje Mts, mostly outcrops of calcite marble can be found, which in places turn into dolomite marbles. The protolith carbonate rocks contained also detritical minerals, which remained unchanged or formed new minerals during metamorphosis. Minerals in the Pohorje marbles that can be seen as crystals with the naked eye or 10x magnifying loupe and with binocular microscope were investigated. With the aid of Raman microspectroscopy, SEM-EDS analysis and on the basis of morphological characteristics, the presence of 17 different minerals or group of minerals was confirmed. The most numerous and also the most significant were, apart from calcite, tremolite, diopside, gros...

Characteristics of minerals in Slovenian marbles

“…Therefore, we can assume that marbles from Košenjak and Strojna are genetically different from those from Pohorje. This finding is in agreement with findings of Jeršek et al (2013) that Pohorje marble was metamorphosed from calcite prevailing protolith. Presence or absence of strontium could thus be used to distinguish marbles from Pohorje Mts.…”

“…Common accessory minerals are quartz, Narich plagioclase, tremolite, hornblende, diospide, mica, while garnet (mostly almandine), graphite, pyrite and chlorite, epidote, clinozoisite and serpentine group minerals occur rarely (Hinterlechner-Ravnik, 1971). Besides these, titanite, ferric oxides, vesuvianite, scapolite (Jarc & Zupančič, 2009;Jeršek et al, 2013), zircon, rutile and zoisite (Mrvar, 2013) have been found. Accessory minerals occur in bands, and are more frequent on the edges of marble lenses (Mrvar, 2013).…”

“…In the past, much attention was given to metamorphic rocks from Pohorje Mts. (Germovšek, 1954;Hinterlechner-Ravnik, 1971, 1973Janák et al, 2004Janák et al, , 2005Janák et al, , 2006Janák et al, , 2009Janák et al, , 2015Jarc & Zupančič, 2009;Jarc et al, 2010;Jeršek et al, 2013;Mrvar, 2013;Vrabec et al, 2010a, b;Vrabec et al, 2018). Here, the majority of medium to high-grade marbles are located in the eastern and southern parts of the massif between Oplotnica and Dravinja brooks and in the surroundings of Šmartno, where they are placed among gneisses, mica-schists and amphibolites (Hinterlechner-Ravnik & Moine, 1977;Mioč, 1978).…”

Raman microspectroscopic analysis of pigments of the Gothic wall painting from the Dominican Monastery in Ptuj (Slovenia)

“…Some grains of muscovite—KAl 2 (AlSi 3 O 10 )(OH) 2 (100, 196, 216, 263, 407, 704 and 751 cm −1 ), garnet (Raman bands at 167, 350, 500, 555, 635, 856, 912 and 1037 cm −1 indicate composition of almandine‐pyrope garnet solid solution—Fe 3 Al 2 (SiO 4 ) 3 ‐Mg 2 Al 2 (SiO 4 ) 3 ), epidote—Ca 2 Al 2 (Fe 3+ ;Al)(SiO 4 )(Si 2 O 7 )O(OH) (234, 273, 351, 453, 569, 603, 892 and 916 cm −1 ) and phyllosilicate minerals of chlorite group—(Mg,Fe) 3 (Si,Al) 4 O 10 (OH) 2 · (Mg,Fe) 3 (OH) 6 (204, 356, 547 and 679 cm −1 ) were also recognized. The composition of the aggregate suggests the use of local sand, as the geological background includes magmatic and metamorphic rocks overlain by dolomite from the Pohorje area (around 40 km from Ptuj) . In addition, a few ceramic grains were also observed in the investigated samples.…”

“…The composition of the aggregate suggests the use of local sand, as the geological background includes magmatic and metamorphic rocks overlain by dolomite from the Pohorje area (around 40 km from Ptuj). [16,17] In addition, a few ceramic grains were also observed in the investigated samples. The lime binder (Raman bands at 156, 282, 713 and 1087 cm À1 ) was fissured, and lumps of carbonated lime were also observed.…”