During the cokemaking process, a significant amount of mercury occurring in a coal blend is released to the atmosphere. One of the ways of reducing this emission is to reduce mercury content in a coal blend. This could be obtained through the coal washing process. The optimization of this process requires the knowledge of mercury occurrence in coal, especially in its inorganic constituents. A qualitative analysis of mercury occurrence in the inorganic constituents of Polish coking coals was performed using an electron probe microanalyzer (EPMA). For that purpose, selected samples of rejects and middling products derived from the washing process in dense media separators and jig concentrators were examined. The obtained results have confirmed a strong connection between mercury occurrence and the presence of sulfides (pyrite, marcasite, and chalcopyrite) in Polish coking coals. Significant amounts of mercury were also noticed for barite, siderite, and aluminosilicates. The highest value of mercury content, at the level of 0.100%, was obtained for marcasite. For the analyzed coals, the effectiveness of mercury removal in the washing process was determined by the forms of pyrite occurring in coal. The highest values of effectiveness of mercury removal were obtained in the case of coals for which the large framboidal pyrite aggregates with chalcopyrite overgrowths were noticed. It was also found that middling products were characterized by the occurrence of the Hg-rich overgrowths of pyrite on organic matter. To achieve a significant reduction in mercury content in clean coal, it is necessary to develop an effective method of removing this form of pyrite from hard coal.

A geochemically primitive, moderately fractionated, LCT pegmatite from Lutomia (Góry Sowie Block, SW Poland) has been characterized in respect of the primary and secondary phosphate assemblages. The pegmatite crystallized from anatectic granitic magmas mobilized by M 2-3 metamorphism at ~370-380 Ma. Three phosphate assemblages had a different origin: (1) the primary, magmatic one [graftonite-(I)-beusite-(I) + triphylite ± sarcopside], (2) a secondary, metasomatic one [Ca-rich graftonite-(II)-Ca-rich beusite-(II) + wolfeite/triploidite/stanĕkite + hagendorfite/alluaudite + kryzhanovskite ± a Ca-bearing phosphate close to ferromerrillite + fluorapatite], and (3) a secondary, hydrothermal and weathering one [ferrisicklerite ± heterosite + phosphoferrite-kryzhanovskite + ludlamite + vivianite ± hureaulite + earlshannonite-whitmoreite + strunzite-ferrostrunzite + beraunite + dufrénite + jahnsite-(CaMnFe),-(CaMnMn) and-(MnMnMn) + landesite + fairfieldite + Mn 2+-bearing hydroxyapatite]. The magmatic assemblage resulted from the breakdown of a primary, high-T, Ca-and Li-enriched graftonite-like phase. It was induced by cooling and elevated incompatible Ca, Na, Li and F concentrations. The metasomatic assemblage reflects the destabilization of the magmatic phosphates and their Ca-and Na-metasomatism by a high-T fluid connected with a PO 4-bearing melt, which previously had evolved along with graftonite-(I)-beusite-(I). The assemblage of secondary, hydrothermal and weathering, phosphates was a result of lower T alteration by hydrothermal fluids and meteoric water by both topotactic Fe and Mn oxidation as well gradual hydration and Fe oxidation. Taken together, the Lutomia pegmatite has been compared to the phosphate-bearing pegmatite at Michałkowa and the mixed NYF + LCT, PO 4-poor pegmatitic system of Piława Górna.

Tourmalines are a group of minerals which may concentrate various accessory components, e.g., Cu, Ni, Zn, Bi, Ti, and Sn. The paper presents fluor-elbaite and elbaite from a dyke of the Julianna pegmatitic system at Piława Górna, at the NE margin of the Bohemian Massif, SW Poland, containing up to 6.32 and 7.37 wt % ZnO, respectively. Such high amounts of ZnO are almost two times higher than in the second most Zn-enriched tourmaline known to date. The compositions of the Zn-rich tourmalines from Piława Górna, studied by electron micropropy and Raman spectroscopy, correspond to the formulae: ^X(Na_0.733Ca_0.013☐_0.254)_Σ1^Y(Al_1.033Li_0.792Zn_0.755Fe²⁺_0.326Mn_0.094)_Σ3^ZAl₆(^TSi₆O₁₈)(BO₃)₃^V(OH)₃^W(F_0.654OH_0.344), and ^X(Na_0.779Ca_0.015☐_0.206)_Σ1^Y(Al_1.061Li_0.869Zn_0.880Fe²⁺_0.098Mn_0.094)_Σ3^ZAl₆(^TSi₆O₁₈)(BO₃)₃^V(OH)₃^W(OH_0.837F_0.163), respectively, with Zn as one of the main octahedral occupants. A comparison with other tourmalines and associated Zn-rich fluor-elbaite and elbaite from the pegmatite indicates that atypically high Zn-enrichment is not a result of Zn-Fe fractionation, but dissolution and reprecipitation induced by a late (Na,Li,B,F)-bearing fluid within the assemblage of gahnite spinel and primary schorl-type tourmaline. This strongly suggests Na-Li-B-F metasomatism of gahnite-bearing mineral assemblages as that is the only environment that can promote crystallization of a hypothetical Zn-dominant tourmaline. The compositions of the Zn-rich fluor-elbaite and elbaite suggest three possible end-members for such a hypothetical tourmaline species: NaZn₃Al₆(Si₆O₁₈)(BO₃)₃(OH)₃(OH), ☐(Zn₂Al)Al₆(Si₆O₁₈)(BO₃)₃(OH)₃(OH) and Na(Zn₂Al)Al₆(Si₆O₁₈)(BO₃)₃(OH)₃O by analogy with other tourmalines with divalent Y occupants, such as schorl/foitite/oxy-schorl and dravite/magnesio-foitite/oxy-dravite.

Magnetite is an abundant magnetic mineral that commonly records the ancient magnetic field in a wide variety of rock types. When cooled below ≈124 K, magnetite undergoes a phase transition, called the Verwey transition, whose characteristics are highly sensitive to grain size and stoichiometry. Studying the Verwey transition thus yields information on the formation conditions and compositions of rocks. The transition is also stress sensitive, thereby opening an avenue to understanding a rock’s strain history; however, the reason for the stress sensitivity is poorly understood. In particular, the temperature of the transition decreases when measured under pressure, yet mostly increases upon pressure release. Moreover, the stress sensitivity of the transition as a function of dopant concentration, especially after pressure cycling, was never systematically tested. We addressed these issues in order to further develop magnetite as a pressure gauge. Multidomain magnetite samples were pressure cycled up to maximum pressures of ∼5 GPa at room temperature to measure the influence of strain on the Verwey transition temperature as a function of dopant concentration after full decompression. The transition temperature measured via changes in magnetic remanence (⁠|$T_{\rm V}^{M}$|⁠) systematically increased with respect to pressure (P) in more doped samples, where domain wall pinning from impurities dominates |$\mathrm{d}T_{\rm V} ^{\rm M}/\mathrm{d}P$|⁠. In less doped samples, no to only moderate pressure cycling dependence on |$T_{\rm V}^{\rm M}$| was observed. Bulk coercive force (B_c) and magnetic remanence after saturation (M_rs) measured above or below the transition also increased with respect to pressure, but here effects related to permanent strain of the lattice structure prevail, and B_c versus P is steeper for less doped samples. B_c versus P increases in all cases, with a difference in slope dictated by dopant concentrations segregating the first to second-order nature of the transition. Thus, strain developed during pressure cycling controls |$T_{\rm V}^{\rm M}$| and coercivity by a mechanism based on pinning of magnetic domains by both interstitial cations and structural lattice distortions. The combined observables, |$T_{\rm V}^{\rm M}$| and B_c−M_rs, reflect both the dopant level and strain state of magnetite, which can quantify the pressure multidomain magnetite has experienced, especially in the range between 1 and 5 GPa. Based on these new results, we present a model that distinguishes between electronic versus defect-driven processes explaining the strain-related influences on the transition. Magnetite’s use as a geobarometer is thus a measure of its defect state, which is expressed through two somewhat independent mechanisms when sensed by magnetic observations.

Pickeringite, ideally MgAl₂(SO₄)₄·22H₂O, is a member of the halotrichite group minerals XAl₂(SO₄)₄·22H₂O that form extensive solid solutions along the joints of the X = Fe-Mg-Mn-Zn. The few comprehensive reports on natural halotrichites indicate their genesis to be mainly the low-pH oxidation of pyrite or other sulfides in the Al-rich environments of weathering rock-forming aluminosilicates. Pickeringite discussed here occurs within the efflorescences on sandstones from the Stone Town Nature Reserve in Ciężkowice (the Polish Outer Carpathians), being most probably the first find on such rocks in Poland. This paper presents mineralogical and geochemical characteristics of the pickeringite (based on SEM-EDS, XRPD, EPMA and RS methods) and suggests its possible origin. It belongs to the pickeringite–apjohnite (Mg-Mn joints) series and has the calculated formula Mg_0.75Mn_0.21Zn_0.02Cu_0.01Al_2.02(S_{0.99 to 1.00}O₄)₄·22H₂O (based on 16O and 22H₂O). The unit cell parameters refined for the monoclinic system space group P2₁/c are: a = 6.1981(28) Å, b= 24.2963(117) Å, c = 21.2517(184) Å and β = 100.304(65)°. The Raman spectra (SO₄) bands are the intensive 994 cm⁻¹ and a low-intensive 975 cm⁻¹ (ν₁), low-intensive 1081, 1123 and 1145 cm⁻¹ (ν₃), 524, 467 and 425cm⁻¹ (ν₂), 615 cm⁻¹ (ν₄), while those at 344 and 310 cm⁻¹ are attributed to ν_g H₂O and at 223 cm⁻¹ to the lattice modes. Crystallization of pickeringite within the particular tor resulted from a certain set of conditions: climatic (e.g., season, temperature, humidity), physicochemical (e.g., pH, concentration), mineral (the presence of pyrite), and site-related (location and efflorescence protection). The sulfate ions could have been derived from oxidation of pyrite in the Ciężkowice sandstones and possibly are related to local mineral waters.