It is most violent type of volcano that expels gases dusts in enormous quantities. Vesuvian type: It is named after the volcano, the Visuvius, Naples in the Mediterranean. It is highly explosive. Ascending g dusts and ashes form cauliflower like forms. Plinian

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Crystallography is the branch of science that deals with the study crystals. It includes the description of crystals, their classification into different systems and classes in addition to the study of mathematical relationships between different faces, imperfections of crystal growth and crystalline

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A crystal is regular polyhedral forms characterized by flat surfaces know as faces. The development of faces is the manifestation of the internal order arrangement of the atoms and depends on the physicochemical conditions to prevail at the time of formation of

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Face: The most important attribute of a crystal is the presence of flat surfaces known as faces and their arrangement in a distinctive pattern. These are the external expression of the internal atomic structure. The common faces are normally parallel to net-planes

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Examination of a crystal indicates the existence of regularity in the arrangement of like faces, edges, solid angles etc. This regularity constitutes the symmetry of the crystal and depends on the internal atomic structure of the mineral. The symmetry can be defined

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In solid geometry (geometry of three dimensions) the position of lines planes are expressed with respect to three mutually intersecting rectangular references axes. Since the crystals are also three-dimensional bodies bounded by flat faces, reference axes similar to those of solid geometry

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Magma once formed inside the earth tends to move upward. When intrudes into the crust, it forms intrusive igneous rocks. When it extrudes ore or ejects to the surface of the earth it gives rise to volcanoes. A valcano is a coni!

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Most of the crystals are three-dimensional polyhedral forms having a number of faces. The positions of the faces with respect to crystallographic axes are expressed in a fashion almost similar to that of solid geometry. The character and nature of the faces

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Axial relationship: Crystals belonging to isometric or cubic system are referred to three crystallographic axes, which are equal in length and are perpendicular to each other. Since these are mutually interchangeable, they are all designated by letter ‘a’. However, to distinguish them

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(i) Cube or Hexahedron (001)6: The cube is a solid buoy by six square faces and the adjacent faces make 90° angles with other. Each face intersects one crystallographic axis and re parallel with other two. The symbols of the faces towards

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