Garnets is a group of 6 members that are crystallizes in the cubic system with a profound rhobdodecahedral cleavage. Structure Physical and Optical Properties Physical propoerties Optical properties Varities – There are many varities of the Garnet minerals – Occurance –
The mica group of minerals crystallizes in the monoclinic system. They are phyllosilicates with their general formula as – X2Y4-6Z8O20[OH,F]4 Where, X = K, Na, Ba, Ca Y = Al, Mg, Fe+2, Li, Cr, Mn, Zn Z = Si, Al, Fe+3 STRUCTURE physical and optical properties physical properties optical properties Mode of occurrence –
Beta diagrams are generally preferred for analysis of faults, ore shoots, kink-bands and rotational manipulations but for complexly folded terrains, Pi diagrams are preferred. Beta diagram beta diagram A stereographic diagram which represents the trend and plunge of the line produced by the intersection of two planes. In its application in structural geology, the dip and strike of a fold surface / lineation/ bedding are recorded as a great circle,
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Pyroxenes are formed either direct or by the reaction of olivine with quartz. Structure Important minerals – Optical Properties Orthopyroxene Clinopyroxene Alteration – Orthopyroxene alter to serpentine or fibrous amphibole. Augite alters to chlorite/ hornblende. Varities – Occurances – REFERENCES –
Olivine is the mineral group crystallizes first during the magma cooling as per Bowen reaction series. It has the general formula X2SiO4 , where X = Fe, Mg, Mn and Ca. with charge of +2. Structure – Olivine solid solution – Because there is similar ionic radius and ionic charge of cations. olivines make a
The North Singhbhum Mobile Belt (NSMB) is a multiple folded, low to medium grade meta-sedimentary and meta-igneous rocks of Proterozoic age (1.0–2.4 Ga) sandwiched between the Archaean (>2.4 Ga) Singhbhum Craton in the south, and the Meso/Neo-Proterozoic (0.9–1.7 Ga) Chotanagpur Gneissic Complex (CGC) in the north by north-dipping ductile shear zones. Clastic sediments with minor volcanics comprising the
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“A Stratotype or type Section is a geological term that names the physical location or outcrop of a particular reference exposure of a stratigraphic sequence or stratigraphic boundary.” Classification of Stratotypes : GSSP (Global Boundary Stratotype Sections and Point) A GSSP is an internationally agreed upon stratigraphic section which serves as the reference section of
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Common minerals : Andalusite, Sillimanite, Olivine, Enstatite etc. Classes of the System Unit forms of Normal class : Form No. of faces Miller Indices Basal Pinacoid 2 001 front Pinacoid‘a’ PinacoidMacro Pinacoid 2 100 Side Pinacoid‘b’ Pinacoidbrachy Pinacoid 2 010 Prism 4 110 Macro Dome 4 101 Brachy Dome 4 011 Pyramid 8 111
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Common minerals : Zircon, Cassiterite, Rutile are the common minerals Classes of the system Unit forms of Normal class : Form No. of faces Miller Indices Basal Pinacoid 2 001 Tetragonal prism of 2nd order 4 100 Tetragonal prism of 1st order 4 110 Ditetragonal prism 8 hko Tetragonal pyramid of 2nd order 8 101
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