Danish Amoz

METAMORPHIC ROCKS Metamorphic rocks are altered forms of pre-existing rocks which might have been igneous or sedimentary. The alternation may be due to either heat or pressure or by both acting together. Un er t e effect of pressure and temperature certain of the original miners are no longer stable and give place to new minerals. Quartz, e spar, and hornblende are stable under both igneous and metamorphic conditions. In addition to new minerals, new textures arise during the process of alteration or metamorphism. Rocks not altered beyond recognition include quartzite (from sandstone) and slate (from clay). Rocks altered beyond recognition include rocks known as gneisses and schists. The original rock-forming material and the names of original rocks and metamorphic rocks produced by it are given below. Mineral Original rock Metamorphic rock Sand Sandstone Quartzite Clay Shale Slate, mica-schist Calcium ...

Sedimentary Rocks Sedimentary Rocks Sedimentary rocks include all rocks formed by deposition in beds or layers (strata) of the material derived from older rocks and also cover rocks formed by chemical or organic agencies. The materials may be carried by water, wind or glacier, e.g., in the case of sandstone, shale, etc. The majority of these sedimentary rocks are formed by deposition on riverbeds, or seabed and into basins or depressions on the earth's surface. The consolidation of loose sediments into hard also by deposition of cementing materials into spaces between particles of the sediments. The chief cementing materials or some mineral finely spread throughout the rock. The colour of the rock often changes on account of alteration of the original constituents due to atmospheric agencies, chiefly water. The sedimentary rocks were formed practically in the horizontal position but due to earth movements associated with earthquakes or other causes, they were tilted from the horizo...

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...