Garnet Geochemistry of Reduced Skarn System: Implications for Fluid Evolution and Skarn Formation of the Zhuxiling W (Mo) Deposit, China

A newly discovered tungsten ore district containing more than 300,000 tons of WO3 in southern Anhui Province has attracted great attention. The Zhuxiling W (Mo) deposit in the district is dominated by skarn tungsten mineralization. This paper conducted in suit EPMA and LA-ICPMS spot and mapping analysis of the skarn mineral garnet to reveal the evolution of fluids, metasomatic dynamics, and formation conditions of skarn. Two generations of garnet have been identified for Zhuxiling W (Mo) skarn: 1) Gt-I generation garnet is isotropic, Al-rich grossular without zoning. As a further subdivision, Gt-IB garnet (Adr19-46Grs49-77 (Sps+Pyr+Alm)4-5) contains significantly high content of Ti and Mn compared with Gt-IA garnet (Adr3-42Grs53-96 (Sps+Pyr+Alm)1-5). 2) Gt-II generation garnet is anisotropic, Fe-rich andradite with oscillatory zoning. Gt-II garnet displays compositional changes with a decrease of Fe and an increase of Mn from proximal skarn (Gt-IIA) to distal skarn (Gt-IIB) with the presence of subcalcic garnet for Gt-IIB type (Sps+Pyr+Alm = 56–68). The presence of pyrrhotite associated with subcalcic garnet indicates a relatively reduced skarn system. Gt-I grossular is overall enriched in Cr, Zr, Y, Nb, and Ta compared with the Gt-II andradite, and both W and Sn strongly favor Fe-rich garnet compared with Al-rich garnet. Gt-IA grossular garnet presents a REE trend with an upward-facing parabola peaking at Pr and Nd in contrast to low and flat HREE, and Gt-IB grossular garnet has a distinct REE pattern with enriched HREE. Gt-IIA andradite garnet displays a right-dipping REE pattern (enriched LREE and depleted HREE) with a prominent positive Eu anomaly (Eu/Eu* = 3.6–15.3). In contrast, Gt-IIB andradite garnet shows depleted LREE and enriched HREE with a weak positive Eu anomaly (Eu/Eu* = 0–6.0). The incorporation and fractionation of REE in garnet are collectively controlled by crystal chemistry and extrinsic factors, such as P–T–X conditions of fluids, fluid/rock ratios, and mineral growth kinetics. Major and trace elements of two generations of garnet combined with optical and textural characteristics suggest that Gt-I Al-rich grossular garnets grow slowly through diffusive metasomatism under a closed system, whereas Gt-II Fe-rich andradite represent rapid growth garnet formed by the infiltration metasomatism of magmatic fluids in an open system. The Mn-rich garnet implies active fluid–rock interaction with Mn-rich dolomitic limestone of the Lantian Group in the district.

Download Full-text

Magnetite texture and trace-element geochemistry fingerprint of pulsed mineralization in the Xinqiao Cu-Fe-Au deposit, Eastern China

American Mineralogist ◽

10.2138/am-2020-7414 ◽

2020 ◽

Vol 105 (11) ◽

pp. 1712-1723

Author(s):

Yu Zhang ◽

Pete Hollings ◽

Yongjun Shao ◽

Dengfeng Li ◽

Huayong Chen ◽

...

Keyword(s):

Trace Element ◽

Triple Junction ◽

Eastern China ◽

Black Shales ◽

Hydrothermal Fluids ◽

Oscillatory Zoning ◽

Trace Element Geochemistry ◽

Element Geochemistry ◽

Rock Interaction ◽

Multiple Pulses

Abstract The origin of stratabound deposits in the Middle-Lower Yangtze River Valley Metallogenic Belt (MLYRB), Eastern China, is the subject of considerable debate. The Xinqiao Cu-Fe-Au deposit in the Tongling ore district is a typical stratabound ore body characterized by multi-stage magnetite. A total of six generations of magnetite have been identified. Mt1 is commonly replaced by porous Mt2, and both are commonly trapped in the core of Mt3, which is characterized by both core-rim textures and oscillatory zoning. Porous Mt4 commonly truncates the oscillatory zoning of Mt3, and Mt5 is characterized by 120° triple junction texture. Mt1 to Mt5 are commonly replaced by pyrite that coexists with quartz, whereas Mt6, with a fine-grained foliated and needle-like texture, commonly cuts the early pyrite as veins and is replaced by pyrite that coexists with calcite. The geochemistry of the magnetite suggests that they are hydrothermal in origin. The microporosity of Mt2 and Mt4 magnetite, their sharp contacts with Mt1 and Mt3, and lower trace-element contents (e.g., Si, Ca, Mg, and Ti) than Mt1 and Mt3 suggest that they formed via coupled dissolution and reprecipitation of the precursor Mt1 and Mt3 magnetite, respectively. This was likely caused by high-salinity fluids derived from intensive water-rock interaction between the magmatic-hydrothermal fluids associated with the Jitou stock and Late Permian metalliferous black shales. The 120° triple junction texture of Mt5 suggests it is the result of fluid-assisted recrystallization, whereas Mt6 formed by replacement of hematite as a result of fracturing. The geochemistry of the magnetite suggests that the temperature increased from Mt2 to Mt3 and implies that there were multiple pulses of fluids from a magmatic-hydrothermal system. Therefore, we propose that the Xinqiao stratiform mineralization was genetically associated with multiple influxes of magmatic hydrothermal fluids derived from the Early Cretaceous Jitou stock. This study demonstrates that detailed texture examination and in situ trace-elements analysis under robust geological and petrographic frameworks can effectively constrain the mineralization processes and ore genesis.

Download Full-text

Complementary Textural, Trace Element, and Isotopic Analyses of Sulfides Constrain Ore-Forming Processes for the Slate-Hosted Yuhengtang Au Deposit, South China

Economic Geology ◽

10.5382/econgeo.4847 ◽

2021 ◽

Vol 116 (8) ◽

pp. 1825-1848

Author(s):

Wei Li ◽

Nigel J. Cook ◽

Gui-Qing Xie ◽

Jing-Wen Mao ◽

Cristiana L. Ciobanu ◽

...

Keyword(s):

Trace Element ◽

South China ◽

Sulfur Isotope ◽

Gold Mineralization ◽

Oscillatory Zoning ◽

Compositional Variation ◽

Rock Interaction ◽

Icp Ms ◽

Isotopic Analyses ◽

Stage 1

Abstract Yuhengtang is a representative slate-hosted Au deposit in the Jiangnan orogenic belt, South China, with a reserve of ~55 t Au and an average grade of ~3.9 g/t. Gold mineralization is characterized by veinlet and disseminated ores comprising native gold, auriferous pyrite, and arsenopyrite. Paragenesis of the Yuhengtang deposit can be divided into three stages. Pre-ore stage 1 is composed of bedding-parallel layers of pyrite in slate of the Neoproterozoic Banxi Group. Main ore stage 2 represents the Au mineralization stage, and two distinct types of mineralization can be distinguished: visible Au-arsenopyrite-pyrite in quartz veinlets and auriferous arsenopyrite-pyrite disseminated within altered slate. Post-ore stage 3 consists of quartz-pyrite-calcite-ankerite veins. In this study, we integrate electron microprobe, laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and high-resolution ion microprobe (SHRIMP) analyses to document textural, isotopic, and compositional variation among texturally complex pyrite and arsenopyrite assemblages in veinlet and disseminated ores. Additionally, LA-ICP-MS sulfur isotope mapping of pyrite highlights the covariation behavior between trace elements and sulfur isotopes at the grain scale, thus allowing the factors controlling sulfur isotope fractionation in hydrothermal Au deposits to be constrained. Pyrite, of sedimentary origin (stage 1), hosts negligible Au (<1.6 ppm) but is enriched in δ34S (15.6–25.8‰). Pyrite and arsenopyrite from stage 2 veinlet mineralization both display porous and dissolution-reprecipitation textures, have low Au concentrations (<4 and <78 ppm, respectively), and show a large variation in δ34S (–2.7 to 14.7‰ and –10.3 to 12.1‰, respectively). Pyrite and arsenopyrite from disseminated mineralization are, in contrast, characterized by oscillatory zoning textures and homogeneous appearance in backscattered electron (BSE) images, respectively, and are obvious by their relatively high contents of invisible Au (up to 90 and 263 ppm, respectively) and restricted range of δ34S values (0–5.3‰). These data suggest that magmatic-hydrothermal fluids contribute most of the Au and S budget in the Yuhengtang Au deposit. The major differences between veinlet and disseminated mineralization in terms of texture, trace element concentrations, and δ34S signatures of pyrite and arsenopyrite reflect contrasting mechanisms of Au precipitation and an evolution of physicochemical parameters of the ore-forming processes, particularly fO2 and the intensity of fluid-rock interaction. Pyrite from stage 3 appears homogeneous in BSE images yet displays a wide variation in δ34S values (1.2–31.4‰), further highlighting the controlling role played by physicochemical condition (i.e., pressure) on the δ34S signature of sulfides. Results of the coupled LA-ICP-MS sulfur and trace element mapping reveal that some zoned pyrite grains from stage 2 formed via overgrowth of Au-rich, light δ34S (2.4‰) hydrothermal rims onto Au-poor, heavy δ34S (18.1–18.5‰) sedimentary cores. All results support that multiple depositional mechanisms within a dynamic mineral system were responsible for Au concentration and define the specific textural, compositional, and sulfur isotope signatures of sulfides in coexisting vein/veinlet and disseminated mineralization. The new data highlight the ore-forming processes-based interpretation for ore genesis and underpin the importance of performing complementary in situ mineralogical analyses to elucidate the source and evolution of ore-forming fluids and enable correct interpretation of the architecture of the hydrothermal Au system.

Download Full-text

Mineralogy and Geochemistry (HFSE and REE) of the Present-Day Acid-Sulfate Types Alteration from the Active Hydrothermal System of Furnas Volcano, São Miguel Island, The Azores Archipelago

Minerals ◽

10.3390/min11040335 ◽

2021 ◽

Vol 11 (4) ◽

pp. 335

Author(s):

Iuliu Bobos ◽

Celso Gomes

Keyword(s):

Positive Trend ◽

High Field Strength ◽

Acid Sulfate ◽

Rock Interaction ◽

Azores Archipelago ◽

Eu Anomaly ◽

Positive Correlation Coefficient ◽

Furnas Volcano ◽

The Eu ◽

Water Rock Interaction

Acid-sulfate alteration is comprised by clays, sulfate, sinter and native sulphur minerals crystallized as neoformation products from dissolution of primary minerals during water-rock interaction. Smectite, kaolinite, halloysite-7 Å and opal-A occur in assemblages with alunite. Smectite represents a mechanical mixture between two (propylitic and acid-sulfate) alteration types. High amounts of high-field strength elements (HFSE) and rare earth elements (REE) were measured in acid-sulfate rocks. The Nb vs. Ta and Zr vs. Hf show a positive trend and a widely scattered relationships, suggesting a large fractionation during acid-sulfate alteration. Higher ∑REE amounts (up to 934.5 ppm) were found in clay-sulfate assemblages and lower ∑REE amounts in sinter (opal-A ± sulfate, 169.05 ppm) than to fresh rocks (up to 751.2 ppm). The acid-sulfate rocks reveal a distinctive gull-wing chondrite-normalized pattern with a negative Eu anomaly and light- and heavy-REE “wings” similar to the gull-wing pattern of fresh rocks. The Eu/Eu* shows a large fractionation of acid sulfate rocks from 0.16 to 0.78 with respect to fresh trachyte products (0.10 to 0.38). Variation of (La/Sm)N and (La/Yb)N ratio show a large fractionation of light-REE and heavy-REE. The Y vs. Dy and Y vs. Ho show a very good positive correlation coefficient and a large Y fractionation in acid-sulfate rocks with respect to fresh rocks.

Download Full-text

The ‘europium anomaly’ in plants: facts and fiction

10.31223/x5kg8j ◽

2021 ◽

Author(s):

Olivier Pourret ◽

Antony van der Ent ◽

Andrew Hursthouse ◽

Dasapta Irawan ◽

Haiyan Liu ◽

...

Keyword(s):

Rare Earth ◽

Rare Earth Elements ◽

Data Availability ◽

Soil Systems ◽

Eu Anomaly ◽

Interference Correction ◽

Icp Ms ◽

Fair Principles ◽

Preferential Uptake ◽

Ree Pattern

Rare earth elements (REEs) and normalized REE pattern determined in plant and soil samples represent powerful tools to trace biogeochemical processes during weathering, soil genesis and processes in the rhizosphere, and thus publications reporting rare earth elements and normalized REE pattern in soil systems and plants are increasing rapidly. Generally, a normalized REE pattern allow for the recognition of an anomalous concentrations of an individual REE. In the literature anomalies are predominantly reported/focused for/on the redox-sensitive elements cerium (Ce) and europium (Eu) that can shift their oxidation state during interactions with organic and inorganic soil phases and biological processes affecting the elements’ mobility in soil and uptake by plants. Thus positive Eu anomalies in plants are often interpreted as a consequence of reduction of Eu3+ to Eu2+ in the rhizosphere followed by a preferential uptake of Eu2+. However, due to an analytical artefact in ICP-MS analysis, a false Eu anomaly may be reported. This can be avoided by using a barium (Ba) interference correction. We draw attention to the possibility of this problem and to being aware of potential occurrence when Eu anomalies are reported. Finally, we recommend (i) including information on how this potential problem was dealt with in the Materials and Methods section of articles and (ii) how to implement FAIR principles in the section (including data availability on an open repository).

Download Full-text

Geochemical behavior of REE associated with Laterization process in Daklak Province, Southern Viet Nam

Science and Technology Development Journal ◽

10.32508/stdj.v17i3.1477 ◽

2014 ◽

Vol 17 (3) ◽

pp. 69-75

Author(s):

K. Okamura ◽

K. Watanabe ◽

K. Yonezu ◽

Huyen Thuong Dang ◽

Du Cong Do ◽

...

Keyword(s):

Noble Metals ◽

Xrd Analysis ◽

The Other ◽

High Demand ◽

Basaltic Rocks ◽

Southern Vietnam ◽

Ce Anomaly ◽

Eu Anomaly ◽

Other Hand ◽

Ree Pattern

The importance of REE for modern industries is proved by the high demand. The abundance of REE is richer than that of noble metals like gold or silver. However, supply sources are concentrated in China. The share of the product of REE was highest in 2009 (over 90%) and that is used as a national strategy.Mining industry in Vietnam is mainly developed in northern part. Deposits of principle metals are located around Hanoi, and REE deposits (Dong Pao) is also explored in Lai Chau Province. On the other hand, few bauxite mine is in southern Vietnam and the REE exploration is not conducted enough. Therefore, the study about REE in southern Vietnam is significant. Samples are from mainly basalt and granite. REE pattern, which is normalized by the abundance of chondrite, of basaltic rocks and laterites shows that is decreases monotony. That amount of REE is low (50-180ppm). REE pattern of magnetite rocks and laterites has no Eu and Ce anomaly. On the other hand, illuminate rocks and laterites have strong negative Eu anomaly. Clay minerals were observed by XRD analysis using hydraulic elutriation. The result of REE pattern and sequential extraction, it is indicated that the form of HREE is changed and adsorbed to clay and LREE is leached out. In tailing in Stop 16, it is observed that the concentration of HREE (about 3 times to 5 times than that of before washing). Eu anomaly is affected by reductive environment of the cooling of magma, and it is considered that Ce anomaly is occurred by the change of Ce form (Ce3+ to Ce4+). CeO2 is insoluble to water in the soil. From the XRD analysis, the cause of HREE concentration in water treatment is considered by the clay mineral

Download Full-text

Characterization of the fluid-rock interaction in the Colombian emerald deposits

10.5194/egusphere-egu2020-16525 ◽

2020 ◽

Author(s):

Germán David Moreno Boada ◽

Sheng-Rong Song

Keyword(s):

Inductively Coupled Plasma ◽

Major And Trace Elements ◽

Black Shales ◽

X Ray Diffraction ◽

Rock Interaction ◽

Inductively Coupled ◽

Colombian Andes ◽

Exploration Tool ◽

Host Rocks

Emerald is a high-value gemstone and a variety of the Beryl group that contains traces of Chromium and Vanadium which give them their characteristic green color.&#160; Colombian emerald deposits have been found within two main narrow belts both of them located in the Eastern Cordillera, one of the three main ranges that constitute the Colombian Andes along with the Central and Western Cordilleras.Several authors (Kozlowski et al. 1998; Ottaway et al. 1994; Giuliani et al. 1993b) have established that the interaction between hydrothermal fluids and the emerald hosted black shales, leading into an intense albitization and carbonation of the host rocks with the depletion of many major and trace elements, resulting into the emerald mineralization along with the deposition of calcite, dolomite, pyrite, albite, quartz and rarely parasite (Giuliani et al.1995). However, the fluid-rock interaction has not been clearly explained and stablished for both productive and non-productive areas in order to provide a more useful guide for further emerald exploration.&#160; &#160;Inductively Coupled Plasma Atomic Mass Spectroscopy (ICP-AMS) along with X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM) data were obtained from unaltered and altered host rocks including siliceous black shales, carbonated black shales, limestones, and dolomitic limestones. The results were analyzed to establish the geochemical relationships between different lithologies and the occurrence or absence of emerald mineralization for the different emerald belts.The concentration of major, trace and REE elements and particularly the of &#160;Cr, V and Be in the host rocks and the distribution over the studied areas will provide a better understanding of whether those contents are sufficient not only for the formation of emeralds besides of the different minerals in paragenesis. The results of the ongoing results are expected to be used as a possible exploration tool in favor to identify the areas with low potential for emerald mineralization.

Download Full-text

Eu anomaly- reliability of the proxy in inferring source composition of clastic Sedimentary rocks: A case study from western Dharwar craton, Karnataka, India

10.5194/egusphere-egu2020-21526 ◽

2020 ◽

Author(s):

Anirban Mitra ◽

Sukanta Dey

Keyword(s):

Rare Earth ◽

Rare Earth Element ◽

Earth Element ◽

Sedimentary Rocks ◽

Dharwar Craton ◽

Source Rocks ◽

Granitic Rocks ◽

Negative Anomaly ◽

Eu Anomaly ◽

Ree Pattern

Use of trace and rare earth element concentration of terrigenous sedimentary rocks to deduce the composition of their source rocks in the hinterland is a very common and efficient practice. The results of geochemical analysis of the metaquartzarenites located at the basal part of Bababudan and Sigegudda belt, late Archean greenstone sequences of western Dharwar craton show that the sediments were most possibly supplied from Paleo to Mesoarchean granitoids of western Dharwar Craton. Rare earth element patterns of these basal quartzites display fractionated REE pattern in variable degree (LaN/YbN =1.47-10.63) with moderate to highly fractionated LREE (LaN/SmN=2.67-8.93) and nearly flat to slighly elevated HREE (GdN/ YbN=0.62-1.29) and a significant Eu negative anomaly (avg. Eu/Eu*=0.67). In general, presence of negative Eu anomaly in clastic rocks reflect the widespread occurrence of granitic rocks in the source area, which possess negative Eu anomaly. On the other hand, mechanical enrichment of zircon (having negative Eu anomaly, high HREE concentration and low LaN/YbN), if present, will hamper the whole REE pattern of the sediments and necessarily, do not actually mimic the source composition. Here, in our study, the Th/Sc vs Zr/Sc diagram show mineral Zircon has been concentrated by mechanical concentration in the sedimentary rocks. Few quartzite samples which have high Zr content typically exhibit low LaN/YbN values, reflecting pivotal role of mineral zircon in controlling the REE pattern of the sediments. Hence, in this case, we should be cautious in interpreting of the Eu negative anomaly of the basal quartzites for meticulously identifying their source rock composition. More geochemical and other analytical approaches are required in this regard.

Download Full-text

Contrasting settings of serpentinite bodies in the northwestern Zagros Suture Zone, Kurdistan Region, Iraq

Geological Magazine ◽

10.1017/s0016756811000409 ◽

2011 ◽

Vol 148 (5-6) ◽

pp. 819-837 ◽

Cited By ~ 18

Author(s):

NABAZ R. H. AZIZ ◽

KHALID J. A. ASWAD ◽

HEMIN A. KOYI

Keyword(s):

Trace Element ◽

Suture Zone ◽

Carbonate Sediments ◽

Thrust Sheet ◽

Eu Anomaly ◽

Lree Content ◽

Hemipelagic Sediment ◽

Ree Patterns ◽

Ree Pattern ◽

Arabian Platform

AbstractProtrusions and lenses of serpentinite–matrix mélanges occur at several places along the thrust faults of the Zagros Suture Zone. They separate the lower allochthonous thrust sheet, the ‘Lower Allochthon’ (i.e. Walash–Naopurdan nappe), of Paleocene–Eocene age from sediments of the Arabian platform and the upper thrust sheet of Mesozoic, ophiolite-bearing terranes termed the ‘Upper Allochthon’ (i.e. Gemo–Qandil nappe). The serpentinite–matrix mélanges occur mostly as stretched bodies (slices) on both sides of the Lower Allochthon (Hero, Halsho and Pushtashan (HHP) and Galalah, Qalander and Rayat (GQR)). Their overall chondrite-normalized rare earth element (REE) patterns form two main groups. Group One exhibits enrichment in the total REEs (> 1 × chondrite) whereas the Group Two pattern shows depletion (i.e. < 1 × chondrite). Bulk-rock MORB-normalized profiles of Group Two are almost flat in the MREE–HREE region with flattening profiles in the Gd–Lu range (> 3 times the MORB composition). In comparison with Group One, Group Two has extremely high REE content and displays variable depletions in the moderately incompatible high-field-strength elements (HFSEs) (Zr, Hf, Y) relative to their adjacent REEs. The REEs in the GQR serpentinite–matrix mélanges have a noticeably high LREE content, and a positive Eu anomaly, and their HREE content never reaches more than 1 × chondrite (i.e. < 0.01 to 1 × chondrite). The latter indicates that the hemipelagic sedimentary, melt-like components (i.e. high LREE, U/La, La/Sm and low Ba/Th) control the geochemical peculiarities of this type of serpentinite. The HHP serpentinite–matrix mélanges, however, are either equally divided between the two REE pattern groups (e.g. Hero, Halsho) or inclined towards Group One (e.g. Pushtashan). Contrary to GQR serpentinites, the variation in HHP serpentinite–matrix mélanges spans a compositional spectrum from U/La-rich to more Ba/Th-rich. Such ratio variations reflect the large variation in these two subducted sedimentary components (i.e. carbonate and hemipelagic sediment mix). The obvious differences in the trace element signatures of the GQR and HHP serpentinite–matrix mélanges might be related to plate tectonic parameters such as convergence rate, subduction age and thickness and type of subducted slab. It is more likely that the influx of subducted components to the mantle wedge relied heavily on the composition of the sedimentary inputs. These vary considerably with time from the relatively deepwater hemipelagic sediments (Qulqula Radiolarite Formation) to platform carbonate sediments (Balambo limestone). The trace element signatures of the GQR and HHP serpentinite–matrix mélanges might suggest multi-staging of the allochthonous sheet emplacement on the Arabian platform sediments.

Download Full-text

The REE-Induced Absorption and Luminescence in Yellow Gem-Quality Durango-Type Hydroxylapatite from Muránska Dlhá Lúka, Slovakia

Minerals ◽

10.3390/min10111001 ◽

2020 ◽

Vol 10 (11) ◽

pp. 1001

Author(s):

Peter Bačík ◽

Jana Fridrichová ◽

Ján Štubňa ◽

Tomáš Bancík ◽

Ľudmila Illášová ◽

...

Keyword(s):

Photoluminescence Spectrum ◽

Trace Element Composition ◽

Element Composition ◽

Granitic Rocks ◽

Eu Anomaly ◽

Yellow Color ◽

Ree Patterns ◽

Ree Pattern ◽

Oh Content ◽

Ftir And Raman Spectroscopy

In talc-magnesite veins in serpentinite near Muránska Dlhá Lúka (MDL), Slovakia, yellow euhedral to subhedral crystals apatite of a gem quality occur. It has a composition of hydroxylapatite with F− varying between 0.29 and 0.34 apfu, Cl− in range of 0.02–0.05 apfu and calculated OH− content between 0.62–0.68 apfu. Moreover, [CO3]2− molecules were identified by FTIR and Raman spectroscopy. MDL apatite contains only up to 0.003 apfu As5+ and Si4+ substituting for P5+; Ca is substituted by small amount of Na, Fe2+, Mn2+ (all up to 0.006 apfu), and Rare Earth Elements (REE—in total up to 0.017 apfu). Compared to trace-element composition of similar apatites from Durango, Mexico, the REE content in MDL apatite is around ten times lower with Nd > Ce >> La, its chondrite-normalized REE pattern has almost a horizontal slope and larger negative Eu anomaly. The MDL apatite is richer in Mn, Pb and Li, but poorer in As, V, Th and U. The concentrations of Sr and Y are similar. In the optical absorption spectra, the most prominent bands are at 585–590 nm (Nd3+) and between 600 and 800 nm (Mn2+, Ce3+-SiO3− photochromic center and Nd3+). The photoluminescence spectrum of MDL apatite shows bands between 550 and 620 nm (Dy3+, Sm3+, Pr3+ and also Mn2+) which likely enhance its yellow color. MDL hydroxylapatite likely formed from fluids derived from granitic rocks as evidenced by the chondrite-normalized REE patterns, Li, Mn and Y concentrations. The Sr content reflects the host-rock serpentinite composition. Fluids for its crystallization were likely derived from Muráň complex orthogneisses by the Alpine deformation and recrystallization in greenschist to lower amphibolite facies.

Download Full-text