Periodico di Mineralogia

Modern classification of the Alfianello, Monte Milone, and Siena historical meteorites

Valeria De Santis — 2026-03-17

New microchemical and mineralogical data of three historical Italian falls (Alfianello, Monte Milone, and Siena meteorites) are presented here. These three meteorites have been scarcely studied and are amenable to being reinvestigated to update/confirm their classification, in particular looking for possibly overlooked shock features. A petrographic thin section containing fragments of the selected meteorites was provided by the Natural History Museum of the University of Firenze (Firenze University Museum System) and has been studied by optical and electron microscopy (FE-SEM), and electron microprobe (FE-EMPA). The data collected led to the following classification: Alfianello: L6, S5, W0; Monte Milone: L5, S1, W0-1; Siena: breccia LL 3-6, S1, W0- 1. Unlike previous studies, our new investigations revealed that the Alfianello sample displays the presence of ringwoodite (high-pressure polymorph of olivine), whereas the presence of maskelynite (diaplectic glass after plagioclase) was confirmed.

Identification of Au and Cu epithermal and porphyry potentials using the geochemical mineralization probability index, zonality index and fractal modeling in the Bostan Abad region, NW Iran

Zeynab Aslizadeh — 2026-03-17

This study aims to identify the geochemical anomalies of Cu and Au using stream sediment geochemical samples, geochemical maps, geochemical mineralization probability index (GMPI) and an extended zonality index derived from a staged factor analysis (SFA) using a fractal model in the 1:100000 geological map of Bostanabad. The results of factor analysis show that Cu was on factor F3-1 with Fe, Zn, V, Mn, Pb and Au on factor F3-3 with Hg. The C-N fractal approach was used to classify the GMPI data to determine Au and Cu anomalies, and the southern and central regions of the study area exhibit these anomalies. In addition, the zonality index for the two factors F3-1 and F3-2, which were determined after a three-stage factor analysis, was based on the elements associated with the epithermal Au deposit type using the equation (As×Sb)/(Au×Cu), while the Cu-Mo porphyry deposit type was determined by the equation (Zn×Pb)/(Cu×Mo). Subsequently, these zonality indices were categorized using C-A fractal modeling. Significant anomalies of this elevated zonality index and GMPI are associated with plutonic units and silicification as well as the intersections of faults, especially in the northeastern and northern sectors of the Bostanabad region. The data were factor analyzed using factor analysis, GMPI and zonality index to determine the association between the elements and classify them by paragenetic elements using the fractal method. Finally, the largest Cu and Au anomalies are found in the northern and northwestern regions. Field observations and petrographic analyzes, which include polished and thin section evaluation and XRD data, show the presence of pyrite and chalcopyrite mineralization associated with the intrusive rocks in the region. In addition, there is evidence of alteration and silicic dykes in the Eocene pyroclastic layers.

Geostatistical modeling of stream sediment anomalies in the Biga Peninsula, NW Türkiye: A threshold-based approach for mineral exploration

Özlem Sebahat Özerkan — 2026-03-03

The Biga Peninsula (NW Türkiye), a key segment of the Alpine–Himalayan metallogenic belt, is characterized by extensive mineralization and geological complexity. This study integrates stream sediment geochemistry and geostatistics to model the spatial distributions of As, Cu, Pb, Zn, and Cd based on 2,369 stream sediment samples. The geochemical results indicate wide concentration ranges for the elements: As (from 3.00 to 839.00 ppm), Cu (from 3.67 to 1680.00 ppm), Pb (from 5.00 to 3989.62 ppm), Zn (from 8.00 to 17762.20 ppm), and Cd (from 0.10 to 210.20 ppm), with standard deviations ranging from 6.43 ppm (Cd) to 488.18 ppm (Zn). Descriptive statistics reveal non-normal distributions, with strong correlations among Zn-Cd (r=0.92), Pb-Zn (r=0.90), and Pb-Cd (r=0.84), while As and Cu appear to be geochemically independent. Cluster analysis confirms a strong geochemical affinity among Cd, Zn, and Pb, whereas As and Cu remain unrelated. Five statistical methods -arithmetic mean, median, interquartile range, percentile-based approach, and cumulative probability- were used to determine elemental threshold values, leading to the classification of anomalies as moderate, high, and very high. Variogram modeling reveals isotropic spatial patterns, enabling the use of ordinary kriging to estimate values at 15,312 grid points. Anomaly maps highlight a distinct Cd anomaly in the southeast, overlapping Zn-Pb-Cd zones, along with independent Cu-As patterns. Comparison with known mineral deposits confirms strong spatial correlations. High As concentrations were associated with the Sahinli, Kocatarla, and Balya deposits, whereas Cu anomalies aligned with the Koru, Kuşçayır, Handeresi, Bağırkaçdere, Tepeoba, Kocatarla, and Arapuçandere deposits. Pb- Zn-Cd anomalies correspond to mineralized zones such as Koru, Handeresi, Bağırkaçdere, and Balya. This study demonstrates a novel application of integrated geochemical and geostatistical modeling, employing a comparative, threshold-based approach to identify mineral exploration targets in the geologically complex Biga Peninsula.

Fluid inclusion and Pb–O isotope constraints on the genesis of the Jurassic Karaburun VMS deposit (Central Pontides, Türkiye)

Buğra Çavdar — 2026-03-10

The Jurassic Karaburun deposit in Central Pontides is the largest known VMS deposit in Türkiye, containing ~125 Mt of ore averaging 1.16 wt. % Cu, 0.25 wt. % Zn, and 0.05 wt. % Co. Mineralization occurs within low-grade greenschist rocks of the Çangaldağ Metamorphic Complex, a tectonic unit of the Central Pontides. It is associated with volcaniclastic, detrital, and deep-marine sediments, along with cross-cutting mafic dikes and sills. The mineralization is predominantly stratiform, forming sheet-like to tabular bodies with disseminated, banded, pyritic clastic, semi-massive, and massive sulfide textures.

δ¹⁸O values of quartz in different ore textures range from 11.79‰ to 14.40‰, corresponding to calculated hydrothermal fluid values of 1.22-4.20‰ V-SMOW. Fluid inclusions with two phases (liquid + vapor) in the quartz of mineralized sections show eutectic temperatures of −10.9 to −26.0 °C, final ice-melting from −0.8 to −7.5 °C, and homogenization temperatures of 178-301 °C, with salinities of 1.4-11.1 wt. % NaCl eq. (avg. ~6.5 wt. %). Pressure corrections indicate minimum trapping temperatures of ~223 ± 25 °C. Microthermometric, oxygen isotope data and formational settings of the deposit collectively indicate ore-forming hydrothermal fluids are seawater-dominated H₂O–NaCl fluids slightly and likely modified by magmatic fluids/volatiles. Narrowly constrained, non-radiogenic Pb isotope ratios (²⁰⁸Pb/²⁰⁴Pb= 37.463-37.751; ²⁰⁷Pb/²⁰⁴Pb= 15.424–15.503; ²⁰⁶Pb/²⁰⁴Pb= 18.079–18.431) indicate a mantle-derived source for lead in the massive sulfides and they also conform to the global lead evolution curve while showing temporal consistency with the growth of ore lead.

Petrographic, geochemical, and isotopic characterization on the Provenance of Historical Marble and Limestone Columns from Tyana (Cappadocia, Türkiye)

Hacer Bilgilioğlu — 2026-03-25

This study presents a comprehensive geological characterization of marble and limestone columns from the ancient city of Tyana in the Cappadocia region, employing a multi-analytical approach. Mineralogical, petrographic, geochemical, and isotopic analyses reveal that the white marbles exhibit exceptionally high calcite purity and a well-developed granoblastic texture, closely resembling those of the Afyon-Dokimeion quarries. Gray marbles characterized by the presence of quartz and muscovite and relatively lower CaO and δ13C/δ18O values indicate a different stratigraphic level or different diagenetic/metamorphic conditions. In the purple-white marbles, hematite-induced pigmentation, coupled with markedly enriched Fe2O3 and MnO contents and isotopic affinities, strongly indicates a provenance corresponding to the Pavonazzetto variety of Dokimeion marble. In contrast, the limestone specimens, characterized by micritic fabric, bioclastic inclusions, and depleted δ18O values, are interpreted as locally sourced. The integration of mineralogical and isotopic distinctions among these stone groups underscores a deliberate and informed approach to material procurement in Roman architecture, reflecting the strategic utilization of both regional and local lithological resources.

Nanoscale investigation of silver in galena from Lavrion and Chalkidiki mines using microscopic and spectroscopic techniques

Michail Samouhos — 2026-03-18

The nature of silver (Ag) in “pure” galena (PbS) crystals from the historical mines of Lavrion (Attica, Greece) and the Kassandra Mines (Stratoni and Olympias, Chalkidiki, Greece) is investigated in the present study using transmission electron microscopy (TEM) and synchrotron X-ray spectroscopy. The phase composition in the Lavrion sample is complex, including both the presence of nanominerals (Sb-sulfosalts, namely diaphorite-type [Ag₃Pb₂Sb₃S₈], in the size range of 10-500 nm) and Ag+ incorporated into the galena structure at concentrations between 0.11 and 1.83 wt%, as determined by TEM-EDS. In contrast, TEM analysis of the Chalkidiki galena revealed no Ag-bearing phases at the nanoscale, unlike in the case of Lavrion. Further investigation attempted via synchrotron X-ray spectroscopy confirmed the presence of Ag⁺both within the galena and in Sb-sulfosalts with which the galena phase is associated at the macroscopic and micron scales. Therefore, it is concluded that in Lavrion galena, silver occurs both as diaphorite nanoparticles and as Ag⁺incorporated into PbS following a coupled substitution mechanism (Ag⁺⁺Sb³⁺↔2Pb²⁺), while in galena from the Chalkidiki mine, the absence of other metals and metalloids at the nanoscale suggests that Ag appears to be either close to Ag⁰or, more likely, related to a PbS-Ag₂S solid solution.