Carbonatite complexes and associated fenite zones are famous for their high-grade rare metal ores. The carbonatite–fenite complexes generally contain high concentrations of light rare earth elements (LREE), thorium (Th), and uranium (U). While most carbonatites are closely related to continental rift zones, some complexes can be observed in post-collisional tectonic environments. The Özvatan nepheline syenite–carbonatite complex is an example of post-collisional carbonatitic magmatism in Central Anatolia, Turkey. The magmatic suite is generally composed of silica-undersaturated ultra-alkaline rocks and carbonatite dikes accompanied by high-intensity fenite zones. The carbonatites of the complex are generally dominated by coarse-grained calcite minerals accompanied by fluorite phenocrysts and may also contain minor amounts of rock-forming silicate minerals. The metasomatic aureole zones (fenites) are mainly composed of euhedral nephelines, K-feldspars, aegirines, augites, and garnets. Carbonatites of the Özvatan complex show enrichments in Ca and F with depletion of alkaline (K and Na) elements. Carbonatites and fenite zones of the Özvatan complex host a variety of incompatible elements, including La, Ce, Nd, Th, U, and Nb. The isotopic composition and general geochemical properties of carbonatites in the study area represent mantle-derived carbonatites rather than crustal limestones/skarns.

Placer deposits constitute important secondary resources for economically valuable minerals, including rare earth elements (REEs) and heavy minerals such as zircon, rutile, and ilmenite. In this study, representative samples from the Hantepe placer deposit (Çanakkale, Türkiye) were processed to investigate the occurrence, distribution, and beneficiation potential of REE-bearing minerals. The ore was subjected to size classification, followed by gravity concentration on a shaking table and subsequent magnetic separation using a low-intensity disc separator. The resulting products were characterized by X-ray diffraction and X-ray fluorescence. The dominant REE-host minerals were identified as titanite, zircon, apatite, monazite and, allanite, accompanied by magnetite, hematite, quartz, and feldspar as gangue constituents. The non-magnetic final concentrate achieved substantial upgrading of critical elements, with Ce increasing from 868 g/t to 5716 g/t, Nd from 308 g/t to 2308 g/t, and Zr from 1435 g/t to 9748 g/t. Additionally, the magnetic concentrate (7.0 wt.%) was strongly enriched in Fe₂O₃ (70.26%) and V (2359 g/t), indicating its potential suitability as an Fe–V source. Overall, the results demonstrate that combined gravity and magnetic separation constitutes an effective beneficiation strategy for critical mineral recovery from placer systems. These findings establish a strong basis for future pilot-scale studies and the techno-economic evaluation of the Hantepe deposit as an emerging source of strategic and industrially relevant heavy minerals.

Geochemical and mineralogical characteristics of beach sand sediments in southwestern Black Sea: An approach to heavy mineral placers    Hatice Nur Bayram (1*), Aslı Nur Uslu (1), Ali Erdem Bakkalbaşı (1), Demet Kiran Yildirim (1), Zeynep Doner (1), Ali Tugcan Unluer (1)  (1) Istanbul Technical University, Faculty of Mines, Department of Geological Engineering, Istanbul, Turkey (*hnnurbayram@gmail.com)   Coastal or beach placer deposits are enrichments of heavy minerals with significant metal content that have been mechanically formed. This work studies the geochemical and mineralogical characteristics of beach sand sediments of southwestern Black Sea, Turkey which cover approximately 20 km2 area. The study area has 4 main geological units: Upper Cretaceous moderately-K kalkalkaline Istanbul volcanics, Oligocene Danismen Formation which is dominated by flood plain, marshy and lake environments, Upper Miocene-Pliocene Belgrad Formation which is dominated by terrestrial deposits, mostly gravel, sand and clay dominated and Quaternary formations which include sandy beaches, sand dunes and river alluvials. A total of 8 beach sand samples were analyzed by X-ray Diffraction (XRD) and X-ray Fluorecance (XRF). Mineralogical compositions are mainly dominated by quartz, siderite, albite, calcite and minor amount of magnetite. Siderite-rich beach sands are observed in western part of the study area and mostly derived from Danismen Formation. Fe2O3 contents of this area are determined up to 40%.  On the other hand, in eastern part of the study area REE-Th-U content of beach sands are relatively higher than source rocks which is defined as a high-Al moderately-K kalkalkaline felsic rocks. The highest HFSE concentration were determined in -250+125µm fraction which consists of 16.5% of eastern beach sand. In this fraction LREE-Zr-U content rise drastically. It can be considered that REE-LREE contents is related with monazite minerals and U contents is related with zircon minerals, considering the monazite and zircon minerals are resistant to weathering and likely to occur in the orthomagmatic phase in the source volcanics. Key words: Beach sand sediments; REE-Th-U; heavy minerals; southwestern of Black Sea; Turkey

Essexites of Kestanbol pluton have significant amount of iron (Fe), titanium (Ti), Rare Earth Elements (REE) and thorium (Th) and considered as the source of Geyikli Heavy Mineral Sands (HMS). Geyikli HMS were enriched by the minerals of magnetite, rutile, monazite and apatite. In Geyikli HMS, REE contents (up to 0,25%) were rised by 4-5 times during placer deposition, mainly caused by the enriching of weathering resistant REE bearing dense phosphate minerals and zircon. On the other hand, Fe (up to 11%) and Ti (up to 2,5%) enrichments are heavily dependent on the magnetite, titanomagnetite and rutile minerals. By using the basic physical mineral processing techniques such sieving, shaking tables, multi gravity seperators, magnetic seperation, it is possible to reach higher grades for both REE and Fe-Ti and to have better initial values for electrochemical mineral processing techniques.