Residual ore deposits are weathered material remaining in situ after soluble constituents have been removed, ore deposit in clay formed by near surface oxidation, e.g. bauxites, residual nickel, extensive iron laterites and soil, (Allaby, 2008). Hence weathering concentrates the residual of useful elements which forms an economic deposit. The relationship between weathering and ore formation is often a key ingredient that leads to the formation of a viable deposit by grade enhancement which commonly occurs in the surficial environment, (Robb, 2005).
Residual deposits is Weathered material remaining in situ after soluble constituents have been removed, or Ore deposit in clay formed by near-surface oxidation, e.g. bauxites (aluminium ore), residual
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The first condition form leaching to occur is the availability of rocks containing minerals of which the undesired ones insoluble under surface. Tropical and sub-tropical climatic conditions are most suitable conditions for chemical decay of those mineral found in-situ. A long continued crustal stability is essential for elements to accumulate and the deposit may be conserved by the topographical relief. For iron ores, under these conditions a limestone formation with minor iron oxides will slowly be dissolved leaving the insoluble iron oxides as a residue, which is sufficient thick to make a workable deposit. According to (Robb, 2005), Residual deposits form in two …show more content…
This ore deposit form by eluviation of nickel from the uppermost lateritic residuum and concentration in underlying saprolitic illuvium as nickeliferous talc, serpentine, or smectite or less commonly together with goethite, Prior to lateritization by interaction with sea water or during low grade metamorphism the olivine and orthopyroxene are rapidly
1. 225 MY : Weathering and erosion of very old folded rocks on an area
The third alluvial deposition consists of sand, silt and minor inter-bedded gravel, and again indicates Brimbank Park’s changing geology over time. (Geological map of Victoria, 1973). These deposits, as well as a nearby fault suggest volcanic activity 5-1.6 million years ago, which explains the olivine basalt (fig. 2) deposits which date back to to the Silurian and Tertiary period.
Riley, C.M. "Lahars." Geological and Mining Engineering Sciences. Michigan Tech. Web. 6 Feb. 2010. .
From the above discussion, it is obvious that the geology of the Superstition mountain and the adjacent areas is complex. Most parts of the mountain express a diverse geological formation. Although the areas surrounding the mountains are believed to be rich in minerals, dead-seated deposits of minerals still seem elusive to the modern mineral prospectors. This explains the absence of mining companies in the area for a long time.
At the end of the last ice age windblown silt covered the lava and basalt deposits. This silt would go on to create the fertile rolling hills of the Palouse. This soil is more than a hundred feet deep in places. Soon, enough time passed for vegetation to take place and more soil started to form.1 The lava flows would end up damming streams flowing from the mountains; in turn forming the current lakes of the region. Layered between the flows of basalt are sand and gravel deposits that washed down from mountains.1
Plummer, C.C., McGeary, D., and Carlson, D.H., 2003, Physical geology (10th Ed.): McGraw-Hill, Boston, 580 p.
...under H₂O-undersaturated conditions, water was structurally bound up to the greenschist facies and then at the start of anatexis the excess water maximized the amount of H₂O-undersaturated melt generated. Furthermore the dissolution of accessory minerals can provide melts with structural components which in turn give clues about melting history and melting conditions, even during rapid melting. The analysis and mass balance of trace elements found in the glasses and residual phases and melt extraction data, together provided evidence that significant amounts of LILE were retained in residual feldspars and biotite crystals up to a high degree of partial melting of the crustal protolith. This is interpreted as meaning that higher temperatures of partial melting are needed to more efficiently differentiate the crust in these mostly incompatible trace elements.
The rock coquina is originally a sedimentary rock. Sedimentary rocks are made up of sediments. The sediments are formed by the mechanical or chemical activities of the natural activities like running water, blowing wind, glaciers etc. this which causes disintegration and decomposition of the pre-existing rocks. The products of decay are transported to some depositional sites by the natural agencies, where they get deposited and with subsequent compaction form sedimentary rocks (Hefferan, O’Brien, 2010). . The sedimentary rocks usually accumulate under a great variety of conditions. This shows the variation in rock, chemical structure as well as in texture. Weathering is the most important process that operates in the formation of sedimentary rocks. Weathering takes place by three methods as: mechanical disintegration, rock decomposition, and biological weathering. Mechanical disintegration is due to frost action, thermal expansion and contraction, aided with gravitational forces. Due to mechanical disintegration, the reduction of size and desegregation of rocks takes place. Chemical weathering is the use of the chemical elements of the atmosphere such as moisture, carbon dioxide, and oxygen (Hefferan, O’Brien, 2010). . This depends on the composition of the rock and the size of the particles that make up them. Biological weathering is a form of weathering caused by growth of roots and burrowing of animals. The environment of a sedimentary rock can show the deposition the quality and quantity of the deposition is affected. Sedi¬mentary rocks differ from environment to environment. These environments include the continental environments such as estuarine, lacustrine (fresh and salt water), deltaic, glacial. Anothe...
Minerals play an important role in our day-to-day life but we often not contemplate how the minerals are obtained. Minerals are scattered all over the world just like any other resources. Due to the natural processes of magma flow, hydrothermal gradients, sedimentation, and evaporation, Minerals are concentrated in various areas of the Earth’s crust. Obtaining these minerals for human use involves four general steps:
The early soils in the Lake District are thought to have been far more alkaline than they are today, particularly those formed from the rocks of the Borrowdale Volcanic Series, which displays veins of white calcite (Pearsall & Pennington, 1973). If a fresh surface of Borrowdale Volcanic rock is exposed, it will react with hydrochloric acid, showing that calcium carbonate is present.
Tarbuck E., Lutgens F., Tasa D., 2014, An Introduction to Physical Geology, 5th Ed, Pearson Education, Upper Saddle River, New Jersey.
Copper ore, usually in the form of chalcopyrite (Figure 2), CuFeS2, is mainly mined using large block cave mines (Figure 3). Block cave mining is a mass mining method that allows for large quantity mining of large lower grade ore bodies. This method of mining is characterized by caving and extracting massive volumes of rock which potentially leads to the formation of a surface depression which is indirectly affected by rock mass and topography of the ground surface. A major challenge when initially starting mining is to predict how the specific ore bodies will cave with respect to the geometry of the undercut. In simple terms, an underground tunnel leads to the draw points where broken, overlying rock is gathered and taken away for processing. Palabora
...ts. In: Regional and Specific Deposits Volume 9 in Handbook of Strata-bound and Stratiform Ore Deposits, 9:77-178.
Chemical Weathering is when water weakens the structure of the rock and Mechanical Weathering is where water seeps into the rock face causing fragments of rock to break off.
As a result of this process, the mine sites "do not develop normal soil structure or support the establishment of a plant cover". Many mine sites have...