Some Placer Deposits On The Basis Of Ganesa
1. PLACER RESIDUAL
Placer residual. Which is a type of particle mineral / ore-forming mineral deposit and accumulate directly above the source rock and has suffered vandalism / destruction of chemical and materials separated from the lighter rock. These types of deposits are formed only on the soil surface is almost flat, which can also be found inside the minerals that are resistant lightweight chemical reactions (eg, veins containing gold or kasiterit)
In this type of placer the enrichment results from the elimination of valueless material rather than from concentration of values brought in from an outside source. Residual placers may be rich but they are not likely to be large and as a class, they have been relatively unimportant.
2. ELUVIAL PLACER
Eluvial placer. Particles of mineral / ore-forming mineral deposit types are deposited on the slopes of the hill a source rock. In some areas found eluvial placer with constituent materials of economic value accumulated in the pockets of the bedrock surface.Eluvial placers usually represent a transitional stage between a residual placer and a stream placer. Where one type merges into another, they cannot be clearly distinguished. They are characteristically found in the form of irregular sheets of surface detritus and soil mantling a hillside below a vein or other source of valuable mineral. It should be noted that the parent vein or lode mayor may not outcrop at the actual ground surface. Eluvial placers differ from residual placers in that surface creep slowly moves the gold and weathered detritus down hill, allowing the lighter portions to be removed by rain wash and wind. As the detrital mass gravitates downhill, a rough stratification or concentration of values may develop but this is rarely perfected to the degree found in stream placer
3. STREAM PLACERS
Stream placers which can be divided into:
- Placer River or commonly referred to as alluvial deposits. This species is most important especially those associated with gold ores are generally associated with iron ore, where the configuration of layers and the density of particles of mineral / ore became important factors in its formation.River deposits are represented by the more extensive gravel flats in or adjacent to the beds of present-day rivers and as a class, they have been our most important source of placer minerals. They are generally similar to creek placers but the gold is usually finer, the gravel well-rounded and large boulders fewer or absent.First, the heavy minerals in the rock source (frozen and metamorphic) formed in a size smaller than the main mineral-forming rocks. Second, sorting and composition of sediment deposition is controlled by gravity and particle size (hydraulic ratio). Although the over-all deposit may be low-grade, pay streaks and bedrock concentrations capable of supporting dredging or other large-scale mining
- Placer Beach. These deposits are formed along the shoreline by the concentration of sea waves and currents along the coast. A wave threw mineral deposit-forming particles to the beach where the water is returned with lightweight materials to be separated from heavy mineral. Increase in size and weight of the particles will be deposited or concentrated at the beach, and then accumulate as clear boundaries and form a layer. This layer shows the reverse order of size and weight of the particles, where the base layer of fine-sized or heavy and rich in minerals to the top gradually become more rugged and low in heavy minerals.Placer beach occurs at different topographic conditions caused by changes in sea level, where the zone of optimum separation of heavy minerals are in the tidal zone of an open coast. The concentration of mineral particles / ore is also possible on the terrace formed by ocean waves. The most important minerals contained in mineral deposit types are: magnetite, ilmenite, gold, kasiterit, diamonds, monazite, rutile, and zircon xenotim.
- Placer Eoulin is a landscape that was formed due to wind activity. Placer is often found in desert regions. The desert itself is more attributable to the influence of climate. Desert sand is defined as an area that has an average rainfall of less than 26 cm / year. While the means of transport by wind is essentially the same as the transport by water is a floating (suspension) and sliding on the surface (traction). In general, fine particles (dust) carried by drift and the size of sand carried by sliding on the surface (traction). This includes transportation of the traction jumps (saltation) and roll (rolling).Deposition by the wind, if wind power is bringing the material is reduced or if it rains, then the materials (sand and dust) will be deposited
Judging from the way or making mechanism of material, there are three kinds of methods in the exploitation of placer mining are:
1. Methods Manual
This method is a way of traditional mining or manually using simple equipment such as panning. Because in general use so that the trays this way also called panning. This method is often also used in the exploratory stage of the sampling methods in placer deposits.The basic mechanism of material separation of mineral impurities is the difference in specific gravity (specifig gravity) and the flow of water or lap trays shake when the rotating direction. Impurity material with specific gravity lighter than gold grains (specific gravity: 14 - 19) will be thrown out, while the gold grains remained behind at the base tray (pan). but the weakness of this method is the acquisition rate is still low. However, in general, still a lot of gold grains are smooth and flat-shaped go wasted with impurities of material available. Mining ways this can be done either individually or in groups.
2. Hydraulic Methods (Hydraulicking)
Hydraulic method of making material way by using hydraulic power (spray water) using a combination of pumps and hydraulic / giant (monitor). In geology, a placer deposit is a mechanical concentration of heavy minerals, which can be an ore deposit if the benefit in terms of its value. In general, these deposits are gold, diamonds, tin (cassiterite), titanium (rutile), platinum, tungsten (sheelite), chromite, magnetite and phosphate. Placer classified by the media as an alluvial (continental detrital), Eolian (wind), and glacial yesterday. In terms of location, is categorized as residual deposits (alluvial), level (side hill), stream (fluvial), the beach, buried or desert.The main requirement of this method is the availability of adequate water. Excavated material is collected in a pitting. Subsequently pumped to a plant called a jig
3. The Method Of The Dredger (Dredging)
This method is a way of making the material by using a piece of equipment called dregg or dredges. This method is applied in aquatic systems. The main requirement of this method is to have the availability of sufficient water to float the dredgers. These dredges can be operated in offshore (offshore mining) or the sea, beaches and rivers, can also be operated in a watery land. Dredges used on alluvial or placer deposits such as gold, tin and other
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