Periodico di Mineralogia

Early-Middle Miocene lacustrine clay minerals, protodolomite, and carbonates in the Hançili Formation (Ankara, Türkiye): mineralogy, sedimentology, and paleoclimate

Zehra Semra Karakaş — 2025-09-19

This study aims to determine the paleoenvironmental and paleoclimatic evolution of the Early to Middle Miocene Hançili Formation in the SW Çankırı-Çorum Basin (Ankara-Çubuk region, Türkiye), developed during the Neo-Tethys closure. Mineralogical, sedimentological, and geochemical properties of lacustrine sediments were analyzed by XRD, SEM, and XRF. The shallow lacustrine system is divided into four depositional phases: (1) mudstones deposited from suspended loads in shallow lakes; (2) sandy and sandy clayey dolomites representing mixed lacustrine/dry margin with seasonal fluvial influx; (3) pure and calcitic dolomites indicative of arid and drying alkaline lake; (4) freshwater limestones with caliche, reflecting humid conditions. XRD analysis identified dolomite, protodolomite, calcite, quartz, feldspar, amphibole, and clay minerals such as smectite, palygorskite, sepiolite, chlorite, and illite. The presence of protodolomite suggests early diagenetic precipitation under variable geochemical regimes preceding complete dolomitization. The occurrence of palygorskite and sepiolite suggests episodic evaporitic conditions and magnesium enrichment. Geochemical weathering indices (CIW, CIA, PIA) indicate moderate to intense chemical alteration in the source area. These findings indicate the Hançili Formation preserves evidence of four distinct climatic stages and documents lacustrine dynamics controlled by climatic fluctuations, regional tectonics, and sediment supply.

WinHolclas, a Windows program for hollandite-supergroup minerals

Fuat Yavuz — 2025-10-24

A Microsoft® Visual Basic software, WinHolclas, has been developed to calculate the chemical formulas of hollandite-supergroup minerals based on data obtained from wet-chemical and electron-microprobe analyses. WinHolclas currently evaluates 12 valid mineral species using the Commission on New Minerals, Nomenclature and Classification (CNMMC) of the International Mineralogical Association (IMA) nomenclature scheme for the hollandite-supergroup minerals, with the simplified general formula (A+, A2+)(M4+, M3+)8O16 in the coronadite and priderite groups. The program recalculates and estimates the chemical formulas of hollandite-supergroup species based on 16 oxygen atoms, with the option of octahedral site total of 8.00 atoms per formula unit normalization. Mineral compositions of the hollandite-supergroup are calculated based on the dominant tetravalent sixfold-coordinated cation, considering the dominant tunnel cation (A+, A2+) and the dominant charge-compensating octahedral cation (M3+, M2+). WinHolclas operates in four stages: (1) it estimates cation and anion contents provided by input chemical data; (2) it determines the dominant tunnel and charge-compensating cation in each group; (3) it assigns the hollandite-supergroup minerals to one of the two groups; and (4) it classifies the hollandite-supergroup species into an appropriate groups such as coronadite and priderite. WinHolclas allows users to: (1) enter up to 42 input variables for mineral-chemical analyses; (2) type and load multiple hollandite-supergroup mineral compositions in the data entry section; (3) edit and load the Microsoft® Excel files used in calculating, classifying, and naming the hollandite-supergroup minerals, and (4) store all the calculated parameters in the output of a Microsoft® Excel file for further data evaluations. The program is distributed as a self-extracting setup file, including the necessary support files used by the program, a help file, and representative sample data files.

Whole-rock and mineral geochemistry of magmatic rocks from the polymetallic Jizvan ore deposit, Tarom- Hashtjin Metallogenic Province, NW Iran: Implications for petrogenesis and tectonic setting

Nader Golshani Nasab — 2025-08-07

The Jizvan polymetallic ore deposit in northwestern Iran is formed by the intrusion of Oligocene igneous bodies into the Eocene pyroclastic-volcanic rocks. The Eocene volcanic rocks are basaltic trachyandesite to trachyandesite with a calc-alkaline to shoshonitic character. Intrusive and volcanic rocks from the Oligocene fall into the syenite and phonolite to trachyte domains, respectively, and are shoshonitic. The multi-element diagrams of magmatic rocks, normalized for the primitive mantle, show similar patterns to the post-collisional magmas, with some fractionation processes. The chondrite-normalized REE patterns for Eocene volcanic rocks resemble those of oceanic island basalts. The geochemical indicators for trace elements and rare earths show that the magmatic rocks were formed by partial melting of an enriched mantle source containing spinel and garnet. The diagrams identifying the tectonic setting show the formation of studied igneous rocks in the continental and post-collisional arcs. The data from microprobe analysis show that the formation temperature of biotite in syenite ranges from 650 to 850 °C, on the basis of the Ti versus Mg/(Mg+Fe) diagram. Thermobarometry, which is based on the composition of clinopyroxene in syenite, reveals that the formation temperature and pressure of this mineral range from 1030 to 1191 °C and from 1.26 to 13.27 kbar, respectively. The AlVI+2Ti+Cr versus Na+AlIV diagram shows the formation of clinopyroxene under conditions of high oxygen fugacity.

New strategy in Chromium extraction: high efficiency without Chromium

Yuliana Sari — 2025-09-19

Chromium (Cr) is a very important metal. In nature, Cr is present in chromium ores and the most important part is chromite. Chromite processing is done using pyrometallurgical and hydrometallurgical technologies. Pyrometallurgical technology is generally done by extracting Cr into Fe and chromium alloys called FeCr and other alloys, while hydrometallurgical technology is generally done by extracting Cr into chromite oxide. In general, Cr extraction is done by 2 methods, namely aluminothermic and electrolytic methods. This shows that Cr metal is obtained through hydrometallurgical technology which is then carried out with pyrometallurgical technology in the aluminothermic process. The latest Cr extraction technology generally uses slag or waste that still contains Cr. Based on considerations regarding the increase in Cr extraction and Cr(VI) produced, the most appropriate method is liquid phase oxidation in chromite ore leaching because it is able to produce Cr extraction up to 96% without producing chromite ore processing residue (COPR) containing Cr(VI), making it possible to utilize COPR directly.

Optimization of feldspar grinding parameters for unlimited processing: Case of Algerian feldspar

Lwiza Maamar — 2025-10-23

Ore grinding is an essential step in mineral processing, which aims to reduce ore dimension and improve recovery in separation stages. An excessive generation of fines during grinding of feldspar ore frequently limits its treatment. Most of the previous studies have focused on the analysis of ultrafine particles to allow for treatment by flotation or leaching, which costs energy and is not environmentally friendly. the present study aims to increase the yield of potash feldspar in a coarser size range (-0.5 to +0.063 mm), allowing the use of alternative, cleaner, and less energy-consuming processing techniques by optimizing the grinding parameters. Optimal recovery of feldspar using physical separation methods was achieved by modifying ball mill parameters according to particle size and employing Response Surface Methodology (RSM) for particles ranging from 0.5 mm to 0.063 mm. The results present a proportional relationship between weight yield and grinding time; the optimum conditions were 16 minutes of grinding with an 82.5% filling charge. The study demonstrated that feldspar ore needs similar grinding time to attain an equivalent particle size, despite if the process proceeds dry or wet, indicating no difference in grinding performance between the two modes. The ratio of fine particles markedly escalates with extended grinding, underscoring the importance of optimizing and controlling grinding time to avoid overgrinding and ensure effective size reduction.

Evaluating the role of geological formations in the heavy metals concentration in the Qarasu River and Gorgan Bay, North of Iran

Sara Sadat Razavi — 2025-10-24

The catchment area of the Qarasu River is among the most important water suppliers to Gorgan Bay. It is located in the north of Iran, in the southern part of the Caspian Sea. This study investigates the role of geological units in the accumulation of heavy metals in the sediments of the Qarasu River and Gorgan Bay. To this end, 21 samples (rock, sediment, and water) were analyzed using the Inductively Coupled Plasma Mass Spectrometry (ICP-MS) method. The value of heavy metals in the studied samples are approximately for cobalt 1-27 (average 13 ppm), chromium 134-7 (average 88 ppm), copper 6-59 (average 32 ppm), nickel 1-76 (average 42 ppm), lead 1-49 (average 23 ppm), vanadium 8-185 (average 100 ppm), zinc 9-157 (average 99 ppm). The concentration of heavy metals progressively increases as one moves away from the river’s source toward the coast of Gorgan Bay. In general, the main sources of heavy metals are the Gorgan schist and the minor Shemshak formation. Human involvement in the concentration of heavy metals in the Qarasu River and the shores of Gorgan Bay is very low to rare.