Feldspar Group
Feldspar are the most common rock forming minerals of the Earth’s crust Structure Classification Physical Properties Optical Properties Under PPL Under XPL Varities : Some advanced material Occurrance : Uses of feldspar :
MINEROLOGY & CRYSTALLOGRAPHY
Amphibole Group
Amphiboles are the common constituents in both Igneous and Metamorphic rocks. General formula of Amphiboles is , W0-1X2Y5(Z8O22)(OH,F)2 Structure Amphiboles Classification Orthorhombic amphiboles Triclinic amphiboles Monoclinic amphiboles General Physical and Optical properties Physical Properties Optical properties
Crystal System and Their Identification
The crystallographic axes are the imaginary lines that we can draw within the crystal lattice. These crystal axis than works as the coordinate system within the crystal. These are well defined lines for the crystals. “On the basis of number of crystal axes and mutual relationship between them we define a crystal system“ Crystal system
Crystal System and Their Identification Read More »
Crystal Forms
There are three elements of crystal forms. The face, edge and solid angle. Forms – It is a group of faces which have a like positions with respect to the crystallographic orientations. Forms may be classified in the following three ways – 1st way 2nd way 3rd way Simple form – when a crystal is
Carbonate Group
The carbonate mineral group form in the environment where water and carbon-di-oxide are present. The (CO3)– complex are basic building units of all carbonate minerals and are responsible for the properties to group. An acid test is widely used for identification of carbonates. Calcite Group (Hexagonal) Dolomite Group (Hexagonal) Aragonite Group (Orthorhombic) Calcite [CaCO3]Magnesite [MgCO3]Siderite
Garnet Group
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 –
Mica Group
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 –
Pyroxene Group
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 Group
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
Orthorhombic System
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
Orthorhombic System Read More »