Danish Amoz

types of rocks Rocks are divided as follows into three great groups based on the origin and mode of formation.  Igneous Rocks: Those that have consolidated at or relatively near the earth's surface from molten material called magma originating from within the earth.  Sedimentary Rocks: Those produced chiefly by the breaking up of pre-existing rocks and deposition of the broken material in the form of layers.  Metamorphic Rocks: Those produced from pre-existing rocks by the action of high temperatures and pressures. The rock cycle Igneous Rocks Igneous rocks are formed by the cooling of molten material called magma, at or relatively near the earth's surface. Magma is a Naturally formed mixture of molten rocks and minerals deep down the earth. The constituents of magma are mostly complex silicates and oxides of iron, aluminium, magnesium, calcium, sodium and potassium. Silica is always present in 35 to 75%. Most of the constituents of magma are nonvolatile with fusion temp...

The most Common rock forming minerasl are listed below. 1- Silicates The felspars These are complex silicates of aluminium with potash, soda or lime and are most abundant in igneous rocks. Potash felspar, also known as orthoclase, is the most common type. It is white, grey or pink in colour with a glassy lustre. When weathered it leaves a hydrated silicate of aluminium known as kaolin or china clay. the soda and lime felspars are known as plagioclase. they also decompose and disintegrate in a similar way. [lagioclase felspars occur in most igneous rocks, especially the darker varieties rich in lime. the specific gravity of felspars is between 2.6 - 2.7 and its hardness on the scale of Mohs is 6. Mica this occurs as a white variety known as muscovite (a silicate of aluminium and potassium) and as a black variety known as black mica or biotite (a silicate of aluminium, iron and magnesium). the mica can be easily scratched by fingernail and has a well-developed cleavage. it is a common co...

 Coal Dust Explosion  Definition  An explosion is the Sudden combustion process of great intensity characterised by mechanical destructive effects through pressure and heat. For coal dust to ignite, combustible dust may be present in form of thick clouds.  Thick cloud of coal dust + O2 + ignition source (flame) ==> initiates combustion of coal Stages of Coal dust combustion stage 1  Ignition often starts as a puff, i.e. sudden combustion of part or whole of the air-borne dust with high temperature, but no marked effects. stage 2 The transition from Puff to Explosion; during this stage Pressure in burning layers increases as the heat of combustion, is transferred to surrounding unburnt layers due to radiation. stage 3 full fledge explosion; when the pressure value exceeds a certain value, a full-fledged explosion in which combustion occurs at a very rapid rate as a result heat is transferred totally rather than lost to its surrounding.  once the pressure ...

Minerals What is a mineral? Defining a mineral. A mineral is a naturally occurring inorganic solid, with a definite chemical composition, and an ordered atomic arrangement.  minerals possess definite physical properties by virtue of which they can be distinguished from one another. the most important physical properties are as follows: Colour: Some minerals possess a characteristic colour, e.g. galena, magnetite, olivine, etc' but in some others, the colour is variable e.g. quartz. Specific gravity: Most rock_forming minerals have a specific gravity between 2 and 4.  Lustre:  the lustre may be metallic (line galena or iron pyrites), pearly (like talc), or silky. Taste and smell:  Rock salt, alum, and other minerals can be recognized by their taste. Streak:  When drawn over paper or an unglazed porcelain plate, a few minerals leave a coloured mark known as the streak; for instance, graphite gives a black streak; hematite leaves a cherry red streak. Crystalline: A...

Mining Geology Introduction What is mining? Mining is the process of excavating minerals of economic value from the earth’s crus for benefit of mankind. Here we can assume that the earth’s crust, the outer surface of the earth, including the oceans, lakes and rivers, extends to depths of 30 to 50 km or so. For mining operations, one should have a working knowledge of geology. The word geology means the science of the earth and deals with the natural origin of the rocks that constitute the earth. A person interested in the extraction of minerals from the earth is, however, concerned with the thin surface of rocks that make up the earth crust to a depth of a maximum of 5 km so that geology enables him to locate, and to decide, the sites most economics form mining or quarrying. In geology, the terms minerals and rock have precise but different meanings. A mineral is a homogeneous and naturally occurring substance having definite physical properties and a composition that may be expressed...

Common Minerals About 107 elements are detected in laboratories, of which but only eight are found in abundance in the composition of the outer surface of the earth. These elements make up 98% of the Earth's visible crust. These are given (in order of frequency).  Oxygen              - 47% Calcium                3.5% Talc                     - 28% Sodium                 2.5% Aluminum              - 8% Pvtasym                    2.5% Iron                          - 5% magnesium           2.0% Total                98.5% Combinations of, these e...

Geochemically abundant and scarce metals Industrial and technological Metals applications can be divide into two categories based on their frequency of existence in the Earth's crust. Abundant geochemical metals, which are five elements (aluminium, iron, magnesium, manganese, and titanium), make up more than 0.1 percent of the earth's crust, while geochemical scarce metals, which include other metals as well (Including copper, lead, zinc, gold and silver), account for less than 0.1%. Almost in every rock, by accurate chemical analysis, at least small amounts of all metals can be detected. However, there are important differences in how abundant and rare metals occur in ordinary rocks. Geochemically abundant metals are present as basic constituents in minerals. Basalt, for example, is a common igneous rock composed mainly of the olivine and pyroxene (iron-magnesium silicate) minerals, feldspar (sodium-calcium-aluminium silicate), and ilmenite (iron titanium oxide). Accurate chem...