Danish Amoz

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 wave is formed it stirs up th

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 crystal is a geomet