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What is pyrite?
Pyrite or Iron pyrite (FeS2) is a very common mineral that can be found in sedimentary and low grade metamorphic rocks in the form of crystals. It is often referred to as 'Fools Gold' due to it's gold-like colour. Pyrite can be found in soils and sediments throughout the Earth as myriads of microscoRead more
Pyrite or Iron pyrite (FeS2) is a very common mineral that can be found in sedimentary and low grade metamorphic rocks in the form of crystals. It is often referred to as ‘Fools Gold’ due to it’s gold-like colour. Pyrite can be found in soils and sediments throughout the Earth as myriads of microscopic crystals. This pyrite is formed by bacteria that remove oxygen from sulfate in the water, producing sulfide that reacts with iron to form pyrite. More than 90 percent of the pyrite on Earth is formed by microbiological processes. Pyrite is found in a wide variety of geological settings, from igneous, sedimentary and metamorphic rock to hydrothermal mineral deposits, as well as in coal beds and as a replacement mineral in fossils. Pyrite is a common accessory mineral in sedimentary rocks, particularly in limestone, sandstone and carbonaceous siltstones or shales. Recognized for its brass-yellow color which resembles that of gold, pyrite is a source of iron and sulfur and is used for the production of sulfuric acid. Some types of pyrite contain enough microscopic gold to warrant mining them as a gold ore. Take a magnet with you. Iron pyrite will stick to the magnet because of its high iron content; gold will not. Pyrite doesn’t melt. When heated, it gives off part of its sulphur and turns into pyrrhotite. Further heating, with plenty of air, will cause it to burn, leaving iron oxide (“rust”).
See lessWhat is difference between Gold and Pyrite?
The difference between gold and pyrite: 🔥 ● Gold - Crystals form as cubes or octahedrons but are rare. The usual habits are grains, flakes, nuggets and dendritic masses. Bright yellow color is tarnish resistant. Gold is often rich in silver, when it is paler in color. The band is golden yellow. GoldRead more
The difference between gold and pyrite: 🔥
See less● Gold – Crystals form as cubes or octahedrons but are rare. The usual habits are grains, flakes, nuggets and dendritic masses. Bright yellow color is tarnish resistant. Gold is often rich in silver, when it is paler in color. The band is golden yellow. Gold is opaque and its luster is metallic.
Formation:
Forms mainly in hydrothermal veins, often associated with quartz and sulphides. It also occurs in placer deposits of unconsolidated sand and in sandstone and conglomerate. It is possible to find alluvial gold in the form of grains or nuggets in stream beds. Gold panning by sieving sediments is an age-old method of searching for this rare and precious mineral. Gold can be confused with pyrite and chalcopyrite at first, but only a few tests are needed to identify it.
TESTS Insoluble in all simple acids; soluble in aqua regia.
Group: NATIVE ELEMENTS
Composition: Gold
Hardness: 2½–3
GS: 7:30 p.m.
Cleavage: None
● Pyrite – This mineral occurs as cubic, pyritohedral or octahedral crystals; pairing is common.
The crystal faces are frequently striated. Pyrite can be massive, granular, reniform, stalactitic, botryoidal and nodular. The pale yellow color gives rise to its nickname, “fool’s gold”. It has a greenish-black stripe. Pyrite is opaque and has a metallic luster.
Formation:
Pyrite is a common accessory mineral in igneous, sedimentary, and metamorphic rocks.
TESTS Gives off sparks on impact with a hard metal object. Fuses quite easily.
Group: SULPHIDES
Composition: FeS₂
Hardness: 6–6½
OS: 5.00–5.03
Cleavage: Indistinct
Fracture: conchoidal to uneven
What is Auger Mining?
⚫Auger Mining 🔷Auger mining means a method of mining coal at a cliff or highwall by drilling holes into an exposed coal seam from the highwall and transporting the coal along an auger bit to the surface and includes all other methods of mining in which coal is extracted from beneath the overburden bRead more
⚫Auger Mining
🔷Auger mining means a method of mining coal at a cliff or highwall by drilling holes into an exposed coal seam from the highwall and transporting the coal along an auger bit to the surface and includes all other methods of mining in which coal is extracted from beneath the overburden by mechanical devices located at the face of the cliff or highwall and extending laterally into the coal seam, such as extended depth, secondary recovery systems
As the auger rotates and advances forward, coal is cut and pushed out of the hole by the rotating action of the auger.
🔹The action is similar to that of a carpenter boring a large hole in wood using an auger bit, and that is where the name derives.
🔷Auger mining recovers around one-third of the coal under the highwall, for whatever depth of penetration is achieved.
🔹 Auger cutting heads can be as large as 7 feet in diameter and may be drilled to a depth of more than 300 feet.
When the ultimate pit limit is reached, it is difficult to “pack up and leave” when you see the exposed coal seam.
🔹 So, in some regard, the company looks at this secondary recovery technique, i.e., auger mining, as the “icing on the cake.
🔹” It amounts to coal recovery at a very low cost. It is, however, somewhat problematic and controversial.
🔷The low recovery, less than 35%, means that the majority of the reserve remains in place, but it has been sterilized, i.e., left in a condition where it will be essentially impossible for anyone to recover the remainder in the future.
🔹The holes into the side of the hill create drainage holes for acid-laden water, and that is a big problem.
See lessWhat is room and pillar mining?
⚒ Room-and-pillar mining ◽️In this method, a number of parallel entries are driven into the coal seam. The entries are connected at intervals by wider entries, called rooms that are cut through the seam at right angles to the entries ◽️ The resulting grid formation creates thick pillars of coal thatRead more
⚒ Room-and-pillar mining
◽️In this method, a number of parallel entries are driven into the coal seam. The entries are connected at intervals by wider entries, called rooms that are cut through the seam at right angles to the entries
◽️ The resulting grid formation creates thick pillars of coal that support the overhead strata of earth and rock.
⚫️ There are two main room-and-pillar systems,
▪️the conventional
▪️ the continuous.
◽️In the conventional system, the unit operations of undercutting, drilling, blasting, and loading are performed by separate machines and work crews.
◽️In a continuous operation, one machine—the continuous miner—rips coal from the face and loads it directly into a hauling unit.
➡️ In both methods, the exposed roof is supported after loading, usually by rock bolts.
◽️Under favorable conditions, between 30 and 50 percent of the coal in an area can be recovered during the development of the pillars. For recovering coal from the pillars themselves, many methods are practiced, depending on the roof and floor conditions.
◽️The increased pressure created by pillar removal must be transferred in an orderly manner to the remaining pillars so that there is no excessive accumulation of stress on them. Otherwise, the unrecovered pillars may start to fail. endangering the miners and mining equipment. The general procedure is to extract one row of pillars at a time, leaving the mined-out portion, or gob, free to subside. While extraction of all the coal in a pillar is a desirable objective, partial pillar extraction schemes are more common.
◽️At depths greater than 400 to 500 meters, room-and-pillar methods become very difficult to practice, owing to excessive roof pressure and the larger pillar sizes that are required.
See lessWhat is a placer deposit?
⚒️ Placer deposit ⚒️ 💠 Placer deposit, natural concentration of heavy minerals caused by the effect of gravity on moving particles. 💠 When heavy, stable minerals are freed from their matrix by weathering processes, they are slowly washed downslope into streams that quickly winnow the lighter matrix.Read more
⚒️ Placer deposit ⚒️
💠 Placer deposit, natural concentration of heavy minerals caused by the effect of gravity on moving particles.
💠 When heavy, stable minerals are freed from their matrix by weathering processes, they are slowly washed downslope into streams that quickly winnow the lighter matrix.
💠Thus the heavy minerals become concentrated in stream, beach, and lag (residual) gravels and constitute workable ore deposits.
💠 Minerals that form placer deposits have high specific gravity, are chemically resistant to weathering, and are durable; such minerals include gold, platinum, cassiterite, magnetite, chromite, ilmenite, rutile, native copper, zircon, monazite, and various gemstones.
💠 There are several varieties of placer deposits: stream, or alluvial, placers; eluvial placers; beach placers; and eolian placers.
💠 Stream placers, by far the most important, have yielded the most placer gold, cassiterite, platinum, and gemstones.
💠 Primitive mining probably began with such deposits, and their ease of mining and sometime great richness have made them the cause of some of the world’s greatest gold and diamond “rushes.” Stream placers depend on swiftly flowing water for their concentration.
💠 Because the ability to transport solid material varies approximately as the square of the velocity, the flow rate plays an important part; thus, where the velocity decreases, heavy minerals are deposited much more quickly than the light ones.
💠 Examples of stream placers include the rich gold deposits of Alaska and the Klondike, the platinum placers of the Urals, the tin (cassiterite) deposits of Malaysia, Thailand, and Indonesia, and the diamond placers of Congo (Kinshasa) and Angola.
See lessWhat are hydrothermal veins?
The simplest hydrothermal deposit to visualize is a vein, which forms when a hydrothermal solution flows through an open fissure and deposits its dissolved load. A great many veins occur close to bodies of intrusive igneous rocks because the igneous rocks serve as heat sources that create convectiveRead more
The simplest hydrothermal deposit to visualize is a vein, which forms when a hydrothermal solution flows through an open fissure and deposits its dissolved load.
A great many veins occur close to bodies of intrusive igneous rocks because the igneous rocks serve as heat sources that create convectively driven flows in hydrothermal solutions.
Precipitation of the minerals is usually caused by cooling of the hydrothermal solution, by boiling, or by chemical reactions between the solution and rocks lining the fissure.
Some famous deposits are the tin-copper-lead-zinc veins of Cornwall, England; the gold-quartz veins of Kalgoorlie, Western Australia, Australia, and Kirkland Lake, Ontario, Canada; the tin-silver veins of Llallagua and Potosí, Bolivia; and the silver-nickel-uranium veins of the Erzgebirge, Germany.
Hydrothermal deposits formed at shallow depths below a boiling hot spring system are commonly referred to as epithermal, a term retained from an old system of classifying hydrothermal deposits based on the presumed temperature and depth of deposition.
Epithermal veins tend not to have great vertical continuity, but many are exceedingly rich and deserving of the term bonanza.
See lessWhat is Magmatic Sulfide ore deposit?
Magmatic Sulfides and Cumulates Mafic and ultramafic magmas, like all common magmas, contain the major elements oxygen, silicon, aluminum, iron, calcium, sodium, potassium, and magnesium. But they typically also contain other elements including sulfur, nickel, and less common metals such as platinumRead more
Magmatic Sulfides and Cumulates
Mafic and ultramafic magmas, like all common magmas, contain the major elements oxygen, silicon, aluminum, iron, calcium, sodium, potassium, and magnesium.
But they typically also contain other elements including sulfur, nickel, and less common metals such as platinum, palladium, and chromium.
As these magmas cool and crystallize, the first minerals to form are plagioclase, pyroxene, and olivine – all made of major elements.
Consequently, the concentrations of sulfur and other minor elements increase in remaining melt.
Eventually, sulfur concentration becomes great enough so that sulfide minerals begin to crystallize.
The sulfide minerals, typically containing iron and nickel, may also contain relatively high concentrations of platinum, palladium, and other minor metals.
Sulfides have greater densities than silicate minerals and the mafic or ultramafic melts.
So, the denser sulfide minerals will, over time, begin to sink. Eventually, after more cooling and crystallization, significant deposits of sulfide minerals may accumulate on the bottom of a magma chamber.
The deposits, which may form centimeters-, or meters-thick layer called a cumulate, are often entirely, or nearly entirely, composed of sulfide minerals.
This process produces magmatic sulfide deposits, which are the most important sources of platinum, palladium, chromium, and several other metals.
Cumulate sulfide minerals include pentlandite (Fe,Ni)9S8, chalcopyrite (CuFeS2), pyrrhotite (Fe1-xS), and pyrite (FeS2)
Cumulate sulfide deposits account for almost 60% of the world’s nickel production and more than 95% of platinum and palladium production.
These deposits are associated with mafic and ultramafic magmas but not, generally, with felsic magmas, because felsic magmas are so viscous that they cool and crystallize before dense minerals can settle.
Sulfides are not the only kind of mineral that can become concentrated in a cumulate deposit.
Oxides – including magnetite (Fe3O4), ilmenite (FeTiO3), and chromite (FeCr2O4) – may settle and collect at the bottom of a magma chamber, too.
These chromite cumulates produce not only significant amounts of chrome, but also very large amounts of platinum, palladium, and related elements.
See lessWhat kind of Soils associated with Gold Deposits?
💠Throughout much of human history, many people have been fascinated with gold. 💠 Almost every civilization has prized this special metal. 💠The first question everyone has is “How do I find gold?” After much effort over the millenia, people have developed lots of ways to find that precious metal. 💠SoRead more
💠Throughout much of human history, many people have been fascinated with gold.
💠 Almost every civilization has prized this special metal.
💠The first question everyone has is “How do I find gold?”
After much effort over the millenia, people have developed lots of ways to find that precious metal.
💠Sometimes, mother nature herself provides hints about where she is hiding some gold.
💠One of these natural indicators can be found by looking at the plants and soil where you think gold might be hidden.
Always remember that gold is rarely found in large chunks.
💠It will either consist of tiny flakes, or as thin streaks of material within rocks.
💠 In fact, prospectors refer to the tiny gold flakes found in river sands as “colors.”
💠Plants Which Might Grow Near Gold
💠The easiest and most common way of searching for gold is known as placer mining.
💠 This refers to finding gold found away from its original underground site and moved over time.
💠 Placer mining is most frequently done either at the bottom of streams or where streams used to flow.
Cottonwood trees, which grow in wet areas will also grow over top of the areas where streams used to flow.
💠Although an old stream bed may be dry on the surface, there may still be dampness underground.
💠Even though the trees don’t necessarily indicate that gold is there, they (or any type of riparian plant for that matter) may help you to locate a placer gold source if you are in gold country.
💠One of the plants which often grow in areas over gold deposits is the horsetail plant.
💠Horsetail plants were often used by miners in the past as a guide to where gold might be found.
💠 It can tolerate the existence of heavy metals in the soil, which has made people believe gold may be nearby.
💠 Ironically, the horsetail plant also had a practical use for prospectors during the gold rush.
💠 It was primarily used for washing pots and pans.
💠The Desert Trumpet is another indicator that helps prospectors know where to look for gold.
💠 They require more mineralization in the soil than most desert plants.
💠 The red dirt the Desert Trumpet grows in is likely near heavy metals like gold.
💠The Trumpet is most commonly found in arid parts of the American Southwest.
See less