Mogera Taha’s Post

#Petrography of #gold-bearing quartz #veins involves studying their mineral composition, texture, and structure under a petrographic microscope. This includes identifying minerals like quartz, sulfides (such as pyrite and chalcopyrite), and gangue minerals. #Paragenesis refers to the sequence of mineral formation, which can be determined by studying the relationships between minerals and their textures, such as cross-cutting relationships or zoning patterns. By studying the paragenesis of gold deposits, #geologists can identify the sequence of mineral deposition, including the formation of gold-bearing quartz veins and associated sulfide minerals. This helps in delineating #mineralization zones within a geological area.

Magnetite: A Magnetic Mineral with a Rich History and Diverse Geological Significance • Magnetite, a common black, metallic mineral, is one of the most important iron ores in modern society and has a rich history dating back to ancient civilizations. • It is one of the few naturally occurring magnetic materials and was crucial in the development of navigation, commerce, and warfare. • Magnetite forms in various geological environments, including igneous rocks, contact metamorphic rocks, and hydrothermal veins, and is often associated with other minerals such as apatite, pyroxenes, garnet, and sulfides. • In the Early Proterozoic era, large deposits of magnetite precipitated directly from seawater, reflecting significant chemical changes in the Earth's atmosphere and oceans. • Magnetite's magnetic properties arise from its unique crystal structure and the interaction between ferrous and ferric iron ions, making it distinguishable from other similar minerals. • The iron from magnetite and hematite deposits serves as the primary source for steel used in modern infrastructure, and magnetite has played a crucial role in human civilization, from exploration and trade to the development of compasses. https://lnkd.in/eFbjJ9Wp #electromagnetism #metallurgy #mineralogy

STRATIFORM TYPE ORE DEPOSITS : Stratiform deposits comprise stratified (layered) ore bodies that are conformable with the enclosing rocks . These deposits occur in sedimentary rocks, layered intrusive and extrusive igneous rocks, banded metamorphic rocks and in the weathered zone. These are generally large, cover a broad area, and form region or provinces. These mineral deposits are concentrated within one or more strata of volcano-sedimentary and sedimentary bedded rock formations. The mineralisation is conformable, often associated with primary, sedimentary features and ores are diagenetic to epigenetic. These deposits contribute about 40-60 percent of the lead-zinc reserves and 35-40 percent of the zinc ore reserves. The Mississippi valley Pb and Zn deposits form a good example of stratiform deposits. In India Rampura Agucha, is a stratiform, sediment-hosted Pb-Zn deposit and occurs in Pre-Cambrian Banded Gneissic Complex. #geology #miningIndustry #StratiformDeposits #SedimentaryOreDeposits #LayeredIgneousRocks #BandedMetamorphicRocks #VolcanoSedimentaryFormations #SedimentaryBeddedRocks #DiageneticOres #EpigeneticMineralisation

American Mineralogist: Revisiting the genesis of the adakite-like granitoids in collisional zones: water-fluxed melting of intermediate to felsic rocks with dilution by low Sr/Y phases https://lnkd.in/gbVNrDfF Xie et al. investigated the origin of adakitic plutonic rocks through geochemical and textural characterization of rock-forming minerals in the orthopyroxene-bearing, Zhuyuan granodiorite (West Qinling, China). The study proposes that high Sr/Y signal is primarily controlled by the late-stage orthocryst assemblages (non-sieve textured plagioclase+ biotite + K-feldspar + quartz). The addition of low Sr/Y non-orthocrysts and associated melt may have diluted the primary “adakitic signal” in the magma reservoir, driving the bulk composition to more mafic values. The study also highlights that the high Sr/Y signal, which can be formed under various pressure conditions, is often controlled by source compositions. In this regard, many high Sr/Y adakitic granites cannot be directly used to infer the thickness of the continental crust when the source is a felsic to intermediate protolith melted under water-fluxed conditions.

THE PRIMARY GOLD FORMATION Primary gold refers to gold in its natural state, unaltered by geological or chemical processes. It is often extracted directly from gold deposits in the form of nuggets, glitter or wires. Primary gold is considered pure and untainted by other minerals It begins its formation in the Earth's crust through complex geological processes that often involve hydrothermal fluids. It is formed from MAGMATIC ROCKS rich in gold such as granite intrusions or porphyry-type volcanoes. These rocks are rich in elements such as iron, sulphur, and arsenic, especially sulphur that allows for differentiation or accumulation and its transport. Hydrothermal fluids, which are mineral-rich hot solutions, move through fractures and faults in casing rocks to form systems of transporting gold. These hydrothermal fluids often contain dissolved gold that is then deposited in weak areas along fractures and faults when it comes into contact with minerals that reduce the gold's solubility. Minerals such as quartz, calcite and sulfur often play an important role in the rush of gold creating veins and wires from a few centimeters to several kilometers long.#geology #structuralgeology #miningengineering

Archean “epizonal” orogenic gold: The term “epizonal” orogenic gold was initially termed to refer to shallow formed, low temperature deposits in metamorphic belts, and contributes to the high diversity of mineralization styles included in the general orogenic gold class of deposits. But what constitutes an “epizonal orogenic gold deposit”? The example shown here is from the Archean age Black Fox deposit east of Timmins, Ontario. The deposit comprises crustiform-colloform and cockade breccia textured Fe-carbonate-quartz-graphite-pyrite-chlorite-sericite vein networks (top and center photos) which occur in albite-carbonate-pyrite altered reactive, variolitic pillowed mafic volcanic rocks. Mineralization extends across the unconformity into late basin Timiskaming clastic rocks, attesting to its relatively late timing in regard to the hosting lithological sequence and shallow emplacement depth. The veins are associated with narrow, sericitic, pyritic ductile shear zones (bottom image) to which different vein generations are variably deformed, suggesting syntectonic emplacement. The texture and low-T chalcedonic quartz character is more akin to epithermal textures, although from a mineralogical perspective has assemblages indicating derivation from CO2-methane-Na-rich reduced fluids and narrow semi-brittle shear zones more typical of orogenic gold. These crustiform veins are cut by later stage more crystalline quartz associated with syn-metamorphic fabrics (narrow veins in the top and center photos) that constitute ore in the nearby classic orogenic Black Fox deposit, which hosts more extensively ductile sigmoidal vein arrays and shear zones and that is syn- to post peak metamorphic in timing. Is this earlier brittle, low T Grey Fox mineralization shown here a high-level manifestation of a magmatic-hydrothermal system or a shallowly formed early, pre-peak metamorphic-hydrothermal orogenic gold system? Grey Fox is similar in style to several major Precambrian orogenic gold districts for which the same questions, high level textures, mineralogy and similar field relationships are apparent, and which often have As-Sb-Te metal associations: these include the Kalgoorlie, Sunrise Dam, Jundee, Kanowna Belle, Wiluna and Racetrack deposits in Western Australia, the Red Lake, Kirkland Lake, Canadian Malartic, Ross, and Madrid deposits in Canada, as well as Proterozoic examples in Scandinavia and Australia (e.g. Maud Creek). These too may be overprinted by younger, more typical orogenic gold mineralization styes (e.g. Kalgoorlie overprinted by Mt. Charlotte veins). I’ll be discussing these and other varieties of “epizonal orogenic gold” in the upcoming orogenic gold technical session at the PDAC conference on March 4, which will include a series of talks exploring different styles of orogenic gold. See the link in the comments below for that session. I thank McEwen Mining for permission to show the images here. 

Chromium is one of the many valuable mineral ores that Pakistan is endowed with. The chromite mineral is important economically for the nichrome, paint, stainless steel, and refractory lining industries. Mafic and ultramafic rocks such as harzburgite, pyroxenite, and dunite connected to ophiolites host chromite, a source of chromium. There are two types of chromite deposits: podiform deposits and stratiform (Bushveld) deposits. In layered ultramafic and mafic rocks, stratiform deposits are a buildup of chromite that resembles a sheet. These deposits resemble funnels and are flat or tabular in nature, corresponding to igneous complexes that hold chromite deposits. The ophiolite sequence contains the podiform chromite along with related gabbros, sheeted dykes, mafic cumulates, and tectonics. These chromite deposits are often dispersed and have a variety of asymmetrical morphologies, such as pod or lensoidal structures.  #mining #metals #criticalminerals #australia #china #exploration #geology #research #geosciences #gis #mapping #geological #business

Celatom® Perlite is a hydrated, naturally occurring volcanic rock. 🌋 Its unique structure consists of numerous concentric layers, similar to the layers in an onion. Its natural colour ranges from light pearl grey to dark grey. The distinguishing feature which sets perlite apart from other volcanic siliceous rocks is that when heated above 1600°F, it expands up to 20 times its original size. The expansion is due to the presence of water (nearly 5%) trapped in the crude ore. Perlite is used to filter juices, wastewater, beverages and industrial chemicals. They are produced from inert silicate minerals and meet the purity requirements of many applications, except those requiring the highest degree of clarification (such as polishing). Read more here 👉 https://lnkd.in/eCcKtSfp #perlite #perlitecelatom #filteraid

A rounded to sub-rounded volcanic clast supported polymictic breccia, the clasts are silica dominated with quartz and potassium feldspar, and aphanitic hematitic clasts. Hematite/specks of specular hematite too. The voids within the clast supported brecca are filled by carbonte? with secondary copper (malachite/chrysocolar) patches pervasively spread through out the breccia. Copper assays from several samples returned >0.20% with a peak assay of 1.37% Cu, Au peaked 0.045 g/t Au, silver peaked 17.4 g/t Ag. The outcrop site appears to be at crater of a caldera like topographicalfeature. .