scholarly journals Rare and Critical Metals in Pyrite, Chalcopyrite, Magnetite, and Titanite from the Vathi Porphyry Cu-Au±Mo Deposit, Northern Greece

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 630
Author(s):  
Christos L. Stergiou ◽  
Vasilios Melfos ◽  
Panagiotis Voudouris ◽  
Lambrini Papadopoulou ◽  
Paul G. Spry ◽  
...  
Keyword(s):  
Inductively Coupled Plasma ◽  
Mineral Chemistry ◽  
Critical Metals ◽  
Northern Greece ◽  
Inductively Coupled ◽  
Porphyry Cu ◽  
Icp Ms ◽  
Quartz Monzonite ◽  
Ore Minerals ◽  
Plasma Mass Spectrometry

The Vathi porphyry Cu-Au±Mo deposit is located in the Kilkis ore district, northern Greece. Hydrothermally altered and mineralized samples of latite and quartz monzonite are enriched with numerous rare and critical metals. The present study focuses on the bulk geochemistry and the mineral chemistry of pyrite, chalcopyrite, magnetite, and titanite. Pyrite and chalcopyrite are the most abundant ore minerals at Vathi and are related to potassic, propylitic, and sericitic hydrothermal alterations (A- and D-veins), as well as to the late-stage epithermal overprint (E-veins). Magnetite and titanite are found mainly in M-type veins and as disseminations in the potassic-calcic alteration of quartz monzonite. Disseminated magnetite is also present in the potassic alteration in latite, which is overprinted by sericitic alteration. Scanning electron microscopy and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analyses of pyrite and chalcopyrite reveal the presence of pyrrhotite, galena, and Bi-telluride inclusions in pyrite and enrichments of Ag, Co, Sb, Se, and Ti. Chalcopyrite hosts bornite, sphalerite, galena, and Bi-sulfosalt inclusions and is enriched with Ag, In, and Ti. Inclusions of wittichenite, tetradymite, and cuprobismutite reflect enrichments of Te and Bi in the mineralizing fluids. Native gold is related to A- and D-type veins and is found as nano-inclusions in pyrite. Titanite inclusions characterize magnetite, whereas titanite is a major host of Ce, Gd, La, Nd, Sm, Th, and W.

Using Mineral Chemistry to Aid Exploration: A Case Study from the Resolution Porphyry Cu-Mo Deposit, Arizona

2020 ◽  
Vol 115 (4) ◽  
pp. 813-840 ◽  
Author(s):  
David R. Cooke ◽  
Jamie J. Wilkinson ◽  
Mike Baker ◽  
Paul Agnew ◽  
Josh Phillips ◽  
...  
Keyword(s):  
Inductively Coupled Plasma ◽  
Mineral Chemistry ◽  
Three Dimensions ◽  
Temperature Sensitive ◽  
Blind Test ◽  
Inductively Coupled ◽  
Porphyry Cu ◽  
The North ◽  
Icp Ms ◽  
Volcaniclastic Rocks

Abstract The giant, high-grade Resolution porphyry Cu-Mo deposit in the Superior district of Arizona is hosted in Proterozoic and Paleozoic basement and in an overlying Cretaceous volcaniclastic breccia and sandstone package. Resolution has a central domain of potassic alteration that extends more than 1 km outboard of the ore zone, overlapping with a propylitic halo characterized by epidote, chlorite, and pyrite that is particularly well developed in the Laramide volcaniclastic rocks and Proterozoic dolerite sills. The potassic and propylitic assemblages were overprinted in the upper parts of the deposit by intense phyllic and advanced argillic alteration. The district was disrupted by Tertiary Basin and Range extension, and the fault block containing Resolution and its Cretaceous host succession was buried under thick mid-Miocene dacitic volcanic cover, obscuring the geologic, geophysical, and geochemical footprint of the deposit. To test the potential of propylitic mineral chemistry analyses to aid in the detection of concealed porphyry deposits, a blind test was conducted using a suite of epidote-chlorite ± pyrite-altered Laramide volcaniclastic rocks and Proterozoic dolerites collected from the propylitic halo, with samples taken from two domains located to the north and south and above the Resolution ore zone. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) data of epidote provided indications of deposit fertility and proximity. Competition for chalcophile elements (As, Sb, Pb) between coexisting pyrite and epidote grains led to a subdued As-Sb fertility response in epidote, consistent with epidote collected between 0.7 and 1.5 km from the center of a large porphyry deposit. Temperature-sensitive trace elements in chlorite provided coherent spatial zonation patterns, implying a heat source centered at depth between the two sample clusters, and application of chlorite proximitor calculations based on LA-ICP-MS analyses provided a precisely defined drill target in this location in three dimensions. Drilling of this target would have resulted in the discovery of Resolution, confirming that epidote and chlorite mineral chemistry can potentially add value to porphyry exploration under cover.

A Microscale Analysis of Hydrothermal Epidote: Implications for the Use of Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry Mineral Chemistry in Complex Alteration Environments

2020 ◽  
Vol 115 (4) ◽  
pp. 793-811 ◽  
Author(s):  
Ayesha D. Ahmed ◽  
Louise Fisher ◽  
Mark Pearce ◽  
Angela Escolme ◽  
David R. Cooke ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Laser Ablation ◽  
Inductively Coupled Plasma ◽  
Mineral Chemistry ◽  
Void Space ◽  
Inductively Coupled ◽  
Icp Ms ◽  
Plasma Mass Spectrometry

Abstract High-resolution, quantitative imaging of epidote from the Ann Mason fault block, Yerington district, Nevada, using scanning electron microscopy (SEM), X-ray fluorescence (XRF), and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) has revealed at least two types of epidote (type 1 and type 2), each with different major and trace element chemistry. Type 1 epidote is coarser grained, typically greater than 50 μm in diameter, and forms euhedral crystals that display twins and sector zones enriched in Fe, Sr, and Mn. Type 2 epidote is finer grained, typically less than 30 μm in diameter, irregularly zoned with respect to Fe and Al, and forms polycrystalline aggregates that include void space. Two sources of intragranular compositional variability are defined in this study—one related to different generations of epidote only visible on the microscale, and the other related to crystallographic features such as sector zones and twins. Intragranular compositional variations within Yerington epidotes highlight the potential importance of detailed sample characterization in complex alteration environments prior to undertaking mineral chemistry studies in the context of resource exploration. Based on statistical analysis of LA-ICP-MS spot data from one sample, the optimal number of spot analyses to adequately represent the range in element concentrations within zoned or twinned crystals is determined to be at least 40.

Single Particle Inductively Coupled Plasma Mass Spectrometry: Investigating Nonlinear Response Observed in Pulse Counting Mode and Extending the Linear Dynamic Range by Compensating for Dead Time Related Count Losses on a Microsecond Timescale

2019 ◽  
Author(s):  
Ingo Strenge ◽  
Carsten Engelhard
Keyword(s):  
Mass Spectrometry ◽  
Inductively Coupled Plasma ◽  
Nonlinear Response ◽  
Dynamic Range ◽  
Dead Time ◽  
Inorganic Nanoparticles ◽  
Linear Dynamic Range ◽  
Inductively Coupled ◽  
Icp Ms ◽  
Plasma Mass Spectrometry

<p>The article demonstrates the importance of using a suitable approach to compensate for dead time relate count losses (a certain measurement artefact) whenever short, but potentially strong transient signals are to be analysed using inductively coupled plasma mass spectrometry (ICP-MS). Findings strongly support the theory that inadequate time resolution, and therefore insufficient compensation for these count losses, is one of the main reasons for size underestimation observed when analysing inorganic nanoparticles using ICP-MS, a topic still controversially discussed.</p>

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