Factor analysis of the geochemical associations in the Plavica ore deposit, Republic of North Macedonia

The aim of this study is to investigate the geochemical associations in the Plavica deposit in Republic of North Macedonia. The analyses of drill core samples from the detail exploration works were statistically processed to determine the groups of chemical elements with common spatial distributions. The resulting geochemical groups represent different stages of the ore forming hydrothermal processes. The main ore elements are represented by geochemical association of ([As, Sb, Au, Sn] Cu, Bi, Fe, Ag) which group outlines the ore bodies.

Origin of Life: Aliphatic aldehydes in the Earth’s crust – remains of prebiotic chemistry?

The Origin of Life is a question that has not yet been solved in the natural sciences. Some promising interpretative approaches are related to hydrothermal activities. Hydrothermal environments contain all necessary elements for the development of precursor molecules. There are possibly catalytically active surfaces and wide ranges of pressure and temperature conditions. The chemical composition of hydrothermal fluids together with periodically fluctuating physical conditions should open up multiple pathways towards prebiotic molecules. Already in 2017, we detected prebiotic organic substances, including a homologous series of aldehydes in more than 3 billion years old Archean quartz crystals from Western Australia. In order to approach the question if the transformation of inorganic into organic substances is an ongoing process, we investigated a drill core from the geologically young Wehr caldera in Germany at a depth of 1000 m. Here we show the existence of a similar homologous series of aldehydes (C8 to C16) in the fluid inclusions of the drill core calcites, a finding that supports the thesis that hydrothermal environments could possibly be the material source for the origin of life.

Zinkgruvanite, Ba₄Mn²⁺₄Fe³⁺₂(Si₂O₇)₂(SO₄)₂O₂(OH)₂, a new ericssonite-group mineral from the Zinkgruvan Zn-Pb-Ag-Cu deposit, Askersund, Örebro County, Sweden

Zinkgruvanite, ideally Ba4Mn42+Fe23+(Si2O7)2(SO4)2O2(OH)2, is a new member of the ericssonite group, found in Ba-rich drill core samples from a sphalerite- and galena- and diopside-rich metatuffite succession from the Zinkgruvan mine, Örebro County, Sweden. Zinkgruvanite is associated with massive baryte, barytocalcite, diopside and minor witherite, cerchiaraite-Al, and sulfide minerals. It occurs as subhedral to euhedral flattened and elongated crystals up to 4 mm. It is almost black and semi-opaque with a dark-brown streak. The lustre is vitreous to sub-adamantine on crystal faces and resinous on fractures. The mineral is brittle with an uneven fracture. VHN100=539, and HMohs ≈ 4.5. In thin fragments, it is reddish-black, translucent and optically biaxial (+), 2Vz > 70∘. Pleochroism is strong and deep brown-red (E ⊥ {001} cleavage) to olive-pale-brown. Chemical point analyses by WDS-EPMA (wavelength-dispersive X-ray spectroscopy electron probe microanalyser) together with iron valencies determined from Mössbauer spectroscopy yielded the empirical formula (based on 26 O+OH+F+Cl anions): (Ba4.02Na0.03)Σ4.05(Mn1.79Fe1.562+Fe0.423+Mg0.14Ca0.10Ni0.01Zn0.01)Σ4.03(Fe1.743+Ti0.20Al0.06)Σ2.00Si4(S1.61Si0.32P0.07)Σ1.99O24(OH1.63Cl0.29F0.08)Σ2.00. The mineral is triclinic, in space group P1¯, with unit-cell parameters a=5.3982(1) Å, b=7.0237(1) Å, c=14.8108(4) Å, α= 98.256(2)∘, β= 93.379(2)∘, γ= 89.985(2)∘ and V= 554.75(2) Å3 for Z=1. The eight strongest X-ray powder diffraction lines are the following (d Å (I %; hkl)): 3.508 (70; 103), 2.980(70; 114‾), 2.814 (68; 12‾2), 2.777 (70; 121), 2.699 (714; 200), 2.680 (68; 201‾), 2.125 (100; 124, 204) and 2.107 (96; 2‾21). The crystal structure (R1=0.0379 for 3204 reflections) is an array of TS (titanium silicate) blocks alternating with intermediate blocks. The TS blocks consist of HOH sheets (H for heteropolyhedral and O for octahedral) parallel to (001). In the O sheet, the Mn2+-dominant MO(1,2,3) sites give ideally Mn42+ pfu (per formula unit). In the H sheet, the Fe3+-dominant MH sites and AP(1) sites give ideally Fe23+Ba2 pfu. In the intermediate block, SO4 oxyanions and 11 coordinated Ba atoms give ideally 2× SO4Ba pfu. Zinkgruvanite is related to ericssonite and ferroericssonite in having the same topology and type of linkage of layers in the TS block. Zinkgruvanite is also closely compositionally related to yoshimuraite, Ba4Mn4Ti2(Si2O7)2(PO4)2O2(OH)2, via the coupled heterovalent substitution 2 Ti4++ 2 (PO4)3-→2 Fe3++ 2 (SO4)2− but presents a different type of linkage. The new mineral probably formed during a late stage of regional metamorphism of a Ba-enriched, syngenetic protolith, involving locally generated oxidized fluids of high salinity.

Geotechnical structure interpretation from borehole wall imagery at Mamput Block, Central Kalimantan, Indonesia

One of the considerations in mining excavation is geotechnical conditions especially structure orientation. Its observations can be done on the surface or through the drill core. However, if there is no free vertical plane on the surface and core observation, then it is difficult to find the direction of dip and strike, which then the televiewer technology is used. This study aims to reveal the structural conditions and to observe the strike and dip of rock layers using the High-Resolution Acoustic Televiewer (HIRAT) apparatus. This apparatus is an accurate and reliable method for recording structural data and has widely used in mining activity. Analysis of the structural conditions was carried out with a reading density of 0.20 m. The observations show that the discontinuity plane is generally trending to Northeast - Southwest, with a dip generally below 30°. The results of the structural interpretation of the borehole have various features that are bedding plane, filled fracture/joint, minor/major open joint, broken zone, and washout. This study gives many advantages especially in preparing data for project feasibility related to excavation, underground tunneling, or other constructions.

Trace precious metals in major sulfide minerals from the Federova Tundra platinum group element deposit in the Fedorova-Pana layered intrusion, central Kola Peninsula, Russia

ABSTRACT Drill-core samples from the basal Cu-Ni-platinum-group element mineralization of the Early Proterozoic Fedorova Tundra intrusion in the Fedorova-Pana layered intrusion, central Kola Peninsula, Russia, were studied in two separate projects in Canada and Russia. In Canada, trace precious metal analyses by laser ablation inductively coupled mass spectrometry of 323 base metal sulfide particles [pentlandite (101), pyrrhotite (98), chalcopyrite (25), and pyrite (99)] show that Pd is highly concentrated in pentlandite. Most of the analyses (71%) were done using two master composite samples of comminuted drill core representative of the West Pit and East Pit mineralization, FWMC and FEMC, respectively. Fewer analyses were made of three other comminuted drill core samples from the West Pit referred to as “lithology” samples: OLFW (olivine-bearing rocks), ANFW (leucocratic rocks), and GNFW (gabbronorite). In Russia, 120 polished sections sliced from drill core from the West and East Pits and from four other Fedorova Tundra intrusion deposits (Kievey, Northern Kamennik, Eastern Chuarvy, and Southern Kievey) were studied mineralogically. Platinum group mineral characterization and trace Pd electron probe microanalyses of pentlandite were done using polished sections from all six locations (n = 95). The trace electron probe microanalysis data for Pd in pentlandite from the West (n = 35) and East (n = 19) Pit samples, though at much higher detection levels, are considered to be comparable to the laser ablation inductively coupled mass spectrometry data. The Eastern Chuarvy samples show particularly high Pd concentrations averaging 0.49 wt.% Pd (n = 11) and as high as 1.64 wt.% Pd. The combined data from these studies guides our estimate that pentlandite accounts for 30 to 50% of the Pd in these ores and that Rh solid solution in sulfides may account for >98% of the total Rh.