Haerwusu Coal Mine

Haerwusu Coal Mine

The second biggest coal mine in the world by reserve, and China's largest open-cast coal mine

Haerwusu Coal Mine

Location: The Inner Mongolia Autonomous Region of China.

Products: Coal.

Owner: China’s state-run Shenhua Group.

Geological settings: The coal-bearing sequences in the Guanbanwusu Coal Mine include the Benxi Formation and the Taiyuan Formation (both Pennsylvanian) and the Shanxi Formation (Lower Permian) with a total thickness of 90–210 m (Fig. 2). Coal reserves of the Guanbanwusu Coal Mine amount to 92.04 Mt (Tehong, 2006).The Benxi Formation, with a thickness of 5.27–42 m, lies unconformably on thevMiddle Ordovician Majiagou Formation, and was deposited in a shallow marinevenvironment. The sediments are mainly composed of bauxite, sandstone, mudstone, and siltstone. The Taiyuan Formation, with a total thickness of 12–115 m, is mainly composed of gray and grayish-white quartzose sandstone, mudstone, siltstone, and coal, interbedded with dark-gray mudstone, siltstone, limestone, and thin-bedded quartzose sandstone. It was formed in paralic delta and tidal flat-barrier complex environments. The No. 6 Coal Seam is located at the uppermost Taiyuan Formation and has a thickness between 12.17 and 17.78 m (average 15 m). There are 9 partings with a cumulative thickness of 2 m in the No. 6 Coal Seam. The Shanxi Formation is composed of mainly of terrigenous coal-bearing clastic rocks dominated by sandstones. The formation has a thickness between 21 and 95 m, with an average of 52 m. It was formed in fluvial and delta deposite environments. The Shanxi Formation has five coal seams (Nos. 1, 2, 3, 4, and 5 Coal Seams), but only Nos. 3 and 5 are locally minable. The strata overlying the coal-bearing sequences are non-coal-bearing Upper Shihezi Formation, Lower Shihezi Formation and Shiqianfeng Formation.

Stratigraphic column of the Guanbanwusu Mine, Jungar Coalfield.

Note From Dr. Rabinarayan Mishra

"China's largest open-pit coal mine is located in Haerwusu in the Inner Mongolia Autonomous Region. It started production on 20 October 2008, and is operated by Shenhua Group. Its estimated coal output was forecast at 7 million tonnes in the fourth quarter of 2008.

With a designed annual capacity of 20 million tonnes of crude coal, it will operate for approximately 79 years. Its coal reserves total about 1.73 billion tonnes. It is rich in low-sulfur steam coal. Mines in Inner Mongolia are rapidly expanding production, with 637 million tons produced in 2009. Transport of coal from this region to seaports on China's coast has overloaded highways such as China National Highway 110 resulting in chronic traffic jams and delays.

Covering an area of 67 square kilometers, Haerwusu mine lies in the middle of the Zhungeer Coalfield. At the moment it is the open-cast coal mine with the largest production capacity in China. Work on the mine started in May 2006 and the total investment topped 7 billion Yuan. Incidentally 1 Chinese Yuan Renmimbi or 1 CYR = 1 US$ for general informations."

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Grasberg Gold & Copper Mine

Grasberg Gold & Copper Mine

It is the largest gold mine and the third largest copper mine in the world.

Grasberg Gold & Copper Mine

Location: Papua, Indonesia.

Products: Gold & Copper.

Owner: Freeport-McMoRan.

Deposit Type: Porphyry deposits associated with the 3.2 to 2.7 Ma Grasberg Igneous Complex, porphyry ores of the 4.4 to 3.0 Ma Ertsberg Diorite 2.5 km to the south, and a series of skarns deposits.Together these deposits account for near 80 Mt of copper and around 3900 tonnes of gold (including inferred resources).

Mineralization: Mineralisation associated with the Ertsberg intrusive includes: The Ertsberg stockwork which contained a resource of 122 Mt @ 0.54% Cu, 0.90 g/t Au in 2005.The skarn mineralisation, which includes the: i). GB (Gunung Bijah) - 33 Mt @ 2.5% Cu, 0.8 g/t Au (the original reserve on which mining in the district was commenced), which is surrounded by Ertsberg Diorite near its NW margin; ii). GBT Complex (the vertically stacked GBT, IOZ & DOZ), 1.5 km east of GB on the northern contact, with reserves of >230 Mt @ 1% Cu, 0.8 g/t Au, iii). Dom Skarn, 0.5 km south of GBT, partially enclosed by the intrusive near its SE margin, with >70 Mt @ 1.4% Cu, 0.4 g/t Au, iv). Big Gossan within a fault zone cutting sediments to the west of the Ertsberg Diorite with 33 Mt @ 2.81% Cu, 1 g/t Au, v). Kucing Liar (dated at 3.42 Ma, the oldest mineralisation in the district, predating the Dalam Diorite) is associated with a fault zone between the two intrusive complexes, but close to the Grasberg complex, contains >225 Mt @ 1.42% Cu, 1.57 g/t Au.

Block diagram showing the Grasberg Igneous Complex and zoned alteration. Weak stockwork and potassic alteration associated with South Kali Dikes are not shown.

 

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Yanacocha Gold Mine

Yanacocha Gold Mine

Yanacocha Gold Mine

Location: Cajamarca, Peru.

Products: Gold.

It is the largest gold mine in Latin America, and The second largest gold mine in the world, producing over US$7 billion worth of gold to date.

Deposit Type: High sulfidation- type epithermal gold deposits.

Geological Settings & Mineralization: 

The high-sulfidation epithermal gold deposits are hosted by volcanic rocks that occur at the southern terminus of the northern Peruvian volcanic belt, a continuous sequence of a north-northwest trending Miocene-Pliocene suite of bimodal andesite to rhyolite volcanic rocks that extend into southern Ecuador. In the Yanacocha district, the volcanic pile has been subdivided into three groups: (1) the lower andesite sequence, consisting of an intercalated sequence of block and ash flow tuffs, flow sequences with rare, associated flow domes, and an upper zone dominated by ignimbrites and fine-grained, laminated epiclastic sequences that show a transition into the overlying Yanacocha pyroclastic sequence; (2) the Yanacocha pyroclastic sequence, a variable sequence of lithic to lithic crystal tuffs, extensively altered in the central portion of the district and primary host to the majority of gold deposits within the district; (3) the upper andesite-dacite sequence, consisting of intercalated units of andesite to dacite flows, dominated by multiple flow dome complexes in its upper portion. Ar-Ar age dating within the district has yielded ages ranging from 19 Ma (basal lower andesite) to >12 Ma (upper andesite sequence). The entire volcanic pile has been crosscut by multiple phases of phreatic (vapor phase dominant), phreatomagmatic (intrusive component) and hydrothermal breccias, and intruded by multiple late-stage phases of andesite dikes and dacite to quartz dacite plugs, dikes and stocks (10–8 Ma), the latter of which are associated with shallow Au-Cu porphyry-style mineralization that underlies the high-sulfidation epithermal deposits.

Schematic map showing the geology of western Peru and general location of the Yanacocha mining district.

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Sunrise Dam Gold Mine

Sunrise Dam Gold Mine

Sunrise Dam Gold Mine

Location: Laverton, Western Australia.

Product: Gold.

Geological Settings: The deposit is hosted by the Archaean Norseman-Wilunabelt, in the Eastern Goldfields Province of the YilgarnCraton. The deposit falls within the structurally complex LavertonDomain, which is characterized by tight folding and thrusting. A number of other Au deposits lie within or near the margins of the LavertonDomain, including Laverton, Granny Smith (this volume), Red October (this volume), Childe Harold, Lancefield and Keringal. Most of these deposits are hosted by metasedimentary rocks, a distinctive feature of the Lavertonregion relative to other parts of the YilgarnCraton.

Host Rocks: The host rocks are shallow-dipping interbedded Archaean metasedimentary, metavolcaniclasticand felsic to intermediate metavolcanicrocks (Newton et al., 1998). The metavolcaniclasticrocks are interbedded with BIF. In general, they are thick, bedded to massive and fine upwards. The BIF units are typically 2-10 m thick and commonly grade into magnetite-rich tuffs. A 20-40 m thick mafic intrusive postdates the metavolcaniclasticsequence on the western side of Cleo. Quartzfeldsparporphyries also intrude the sequence at both Cleo and Sunrise and, at Cleo, post-date the mafic intrusive.

Mineralization: The Sunrise Shear, within the Archaean rocks, controls geometry of the mineralization and is thought to have been the main conduit for Au-bearing hydrothermal fluids (Newton et al., 1998). Pyrite replacement of BIF accounts for most of the primary mineralization and is well developed where the shear zones, parallel to bedding, follow the contact of BIF with less competent units. Gold is also associated with quartzankerite- pyrite veins and pervasive ankerite-silica-sericite-pyrite alteration of intermediate volcaniclastichost rocks. Thin quartz-carbonate veins also host Au, but are mostly located in the Sunrise part of the deposit. Supergene mineralization has developed in the weathered bedrock and in transported cover in the eastern part of the study area.

Regional geology and setting of the Sunrise-Cleo Au deposit

(after Newton et al., 1998)

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Bonikro Gold Mine

Bonikro Gold Mine

Bonikro Gold Mine

Location: Bonikro, Côte d’Ivoire.

Product: Gold.

Ore Type: Disseminated.  

Geological Settings & Mineralization: The Bonikro deposit is hosted primarily within a small granodiroite intrusion. Mineralisation extends into surrounding basalts to the south, and is controlled along a moderately dipping shear zone. Gold occurs associated with quartz and pyrite, with the highest gold grades occurring around the intersection of the shear and the granodiorite. Overall, the deposit has an average grade below 2g/t gold.

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Classification of Mineral Deposits

Relation to Host Rocks

Host Rocks

There are three types of rocks that host the mineralization namely igneous, sedimentary and metamorphic.

There are three types of rocks that host the mineralization namely igneous, sedimentary and metamorphic.

The examples of igneous rocks are porphyry copper deposits in granite, platinum-palladium-chromium-nickel deposits in dunite, peridotite, gabbro, norite and anorthosite, tantalite, columbite, cassiterite in pegmatite.

Ore deposits can exclusively be formed under sedimentation process like iron ore as Banded Iron Formation (BIF), and Banded Hematite Quartzite (BHQ), zinc-lead deposits in dolomite, copper-gold in quartzite, diamond in conglomerate and limestones. Metamorphic rocks host important ore deposits generated as contact metamorphic aureoles. As garnet, wollastonite, andalusite, and graphite. The metamorphic equivalent of sedimentary and igneous rocks forms large deposits of marble, quartzite, and gneisses and commonly used as building stones and construction materials.

Different from Host

Gold-bearing quartz veins act as an exclusive host for Au and different from the surrounding rocks such as Kolar gold deposit, Karnataka, India.

Gradational Contact

Are often formed around the vein systems with characteristics disseminated mineral distribution. Bulldog Mountain vein systems, Colorado, show abundance of fine-grained sphalerite and galena, with lesser tetrahedrite and minor chlorite and hematite. The mineralization becomes progressively richer of barite and silver with increasing elevation.

Metal Zoning

occurs in a multiple series of hydrothermal depositional source. Mineralization zoning is characterized by Fe-Ba-Cu-Pb-Ag-Au. Metal zoning is an indication of metal deposition in relative order during primary crystallization or sedimentation. It may be modified by deformation and remobilization at later stage. The common metal zoning is in massive sulfide deposits. e.g. El Guanaco gold-copper in Chile, Zn-Cu-Au-Ag deposits of Scuddles, Golden Grove, Gossan Hill, Western Australia.

Wall Rock Alteration

The mineral deposits formedunder epigenetic condition, magmatic intrusion and hydrothermal depositional environments cause changes in mineralogyincluding formation of new minerals, chemical composition, color and textureof the host rock at the contacts and some distance from the orebody. The size of the alteration halo around the orebody varies from narrow to wider depending on the physical and chemical condition of the process of alteration.

If these alteration halos are identified properly it adds a great value to the mineral exploration in general and particularly for planning drilling targets. The most common form of wall rock alterations are silicification, chloritization, sericitization and serpentinization. Presence of pyrite, siderite, titanium, manganese, potassium, lithium, lead, silver, arsenic, rubidium, barium, calcium, epidote and carbonaceous material is common.

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Cadia-Ridgeway Mine

Cadia-Ridgeway Mine

Cadia-Ridgeway Mine

Location: Orange, New South Wales,is one of three gold mines Newcrest currently operates in Australia.

Products: Copper & Gold. A series of large underground and open-cut gold and copper mines

Ore Minerals: Ore minerals are native gold, chalcopyrite and bornite, mostly occurring within veins, but also disseminated.  Magnetite is a major accessory mineral in veins. Hydrothermal alteration associated with the strongest mineralisation is potassic: orthoclase, albite, actinolite, magnetite, biotite.  This is overprinted by later propylitic assemblages: epidote, chlorite, Fe-carbonate, calcite, hematite dusting. 

Geological setting: The Cadiadeposits are part of a Late Ordovician – Early Silurian porphyry alteration-mineralisationsystem that extends over an area of at least 6 X 2 km within the Ordovician MolongVolcanic Belt of the PalaeozoicLachlan Fold Belt (Newcrest Mining Staff, 1997).  The MolongVolcanic Belt comprises a suite of intermediate to basic volcanics, volcaniclastics, comagmaticintrusions, and limestones.  The suite is probably part of a subduction-related island arc disrupted by later tectonism (Glen et al, 1997).  In the Cadiaarea the volcanicsand intrusions are shoshonitic(Blevin, 1998).

Mineralization: Sheeted quartz vein, stockwork quartz vein, disseminated and skarn, all of which are genetically related to a relatively small (3 X 1.5 km in outcrop) composite intrusion of predominantly monzonitic composition, with a monzodioritic to dioritic rind (Cadia Hill Monzonite).  The Cadia Hill Monzonite intruded Forest Reefs Volcanics (volcaniclastics, lavas, subvolcanic intrusions, and minor limestone) and Weemalla Formation (siltstone, mudstone, minor volcaniclastics).  Emplacement of the Cadia Hill Monzonite was probably facilitated and localised by the development of a major north-west (NW) to south-east (SE) trending dilational structural zone, which is well evident in magnetic data.

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El Chino Copper Mine

El Chino Copper Mine

El Chino CopperMine

Location: Santa Rita, New Mexico, United States.

Products: Copper Deposit.

Ore Type:  Porphyry copper deposit with adjacent copper skarn deposits.

Host rocks: The predominant oxide copper mineral is chrysocolla. Chalcocite is the most important secondary copper sulfide mineral, and chalcopyrite and molybdenitethe dominant primary sulfides.

Geological setting: The CobreMountains are composed of Proterozoic metamorphic and igneous rocks covered by about 3800 to 4800 feet of Paleozoic to Mesozoic sedimentary rocks. Cretaceous diorite to quartz diorite sills subsequently intruded these older rocks. Shortly thereafter, mafic to intermediate composition dikes and other intrusive bodies were emplaced and 2000 feet of intermediate composition lavas and brecciaswere erupted onto the surface. Next, the large granodioriticplutons at Chino and at Hanover-Fierro to the north were intruded. The last stage of intrusive activity in this area was the emplacement of rhyoliticdikes. The multiple intrusions locally domed and folded the older Paleozoic and Cretaceous strata.

Mineralization: Porphyry copper deposit are low-grade (<0.8%) disseminated deposits of copper found in and around small intrusive bodies composed of porhyriticdiorite, granodiorite, monzonite or quartz monzonite (McLemore, 2008). The small plutons (also called stocks) are often shallowly emplaced at depth within 1 to 6 km of the earth's surface. The copper occurs within breccia or in networks of fractures, both in the porphyritic intrusion and in the adjoining country rocks.

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Classification of Mineral Deposits

Depth of Occurrence

Exposedto surface

Mineral deposits like iron ore, bauxite, chromite, copper, limestone and magnesite are exposed to the surface and easy to explore. Although most of the significant exposed ore deposits, namely, Example Outside the Sterling Hill Mine are exposures of the weathered surface of the zinc ore body in the Passaic Pit.  Calamine (zinc silicate) was mined in this oxidized portion of the ore body. Canon City, USA.

Shallow Depth

Deposits like base metals, coal and gypsum are covered by altered oxidized capping or exist at shallow depth or under thick overburden of bedrock. The deposits are Cerro de Maimoncopper-gold deposit at Dominican Republic, Geochemical prospecting and ground geophysical survey will be helpful for discovery of deposits at shallow depth.

Deep-Seated Hidden Deposit

Deep-seated hidden deposits will be the future target of mineral exploration. The key exploration procedures suitable for discovery of an orebody at a depth range of 300-700 m require clear understanding of regional structure, applications of high penetrative geophysical methods and interpretation by simulation tools to identify, describe and delineate. Exploration for such deposits is expensive and associated with considerable economic risk. The high costs result from the necessity of expensive instrumentation and extensive drilling at depth. Ex. The hidden poly-metallic deposits discovered in the past are Neves Corvo copper-zinc-tin, Portugal, at 330-1000 m depth, and SindesarKhurd zinc lead-silver at 130 m depth, India.

Exposed to surface,Shallow depth, Deep-seated hidden deposit

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Geographical Localization

Belt

is a narrow linear stretch of land having series of depositsof associated minerals, such as, Colorado gold-molybdenum belt, US, Grant uranium mineral Belt, New Mexico Khetricopper belt, Rajpura-Dariba-Bethumnizinc-lead-silver belt, Rajasthan, Sukindachromite belt, Orissa, India.

Deposit 

is comprised of a single or a group of mineral occurrences of sufficient size and grade separated by natural narrow barren parting.

Examples Broken Hill group of zinc-lead deposits, Australia, Zawargroup of zinc-lead deposits, India, Red Dog zinc-lead deposit, Alaska, OK Tedicopper deposit, Papua New Guinea, Olympic Dam copper-gold-uranium-silver deposit, South Australia, Neves Corvopoly-metallic deposit, Portugal and Stillwater group of platinum deposit, US.

Block

is a well-defined area having mineral concentration wholly or partly of economic value, such as Broken Hill main, Australia, Bailadiladeposit-14, Central Mochia, India. The blocks in underground mining are subdivided to “Level” (say: upper level, lower level, 500-700 and 300-500 mRL). The levels are further split into “Stope” (say:West 301 stope, North 101 stope, Valley stope). These terms are locally convenient to use for attention and allocation of work activities in mineral exploration and sequencing mine production block.

Belt,Deposit,Block

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