Mica Family.pptx

Mica are a group of silicate minerals whose outstanding physical characteristic is that individual mica crystals can easily be split into extremely thin elastic plates. This characteristic is described as perfect basal cleavage. Mica is common in igneous and metamorphic rock and is occasionally found as small flakes in sedimentary rock. It is particularly prominent in many granites, pegmatites, and schists.

1. DEPARTMENT OF APPLIED GEOLOGY SCHOOL OF ENGINEERING AND TECHNOLOGY DR. HARISINGH GOUR VISHWAVIDYALAYA (A CENTRAL UNIVERSITY) SEMINAR PRESENTATION ON: MICA FAMILY GUIDED BY PRESENTED BY PROF A. K. SHANDILYA GOURAV RAJAK M. TECH 1 ST SEM

2. CONTENTS Introduction Atomic structure Chemistry Some important minerals Use of Mica Mica Distribution in India Bibliography

3. INTRODUCTION Mica is the name given to a group of phyllosilicate minerals that have silicon and oxygen as their two major components. Has Si:O ratio of 2:5 (4:10). Has Perfect Basal cleavage parallel to {001} Hardness is 3 Monoclinic. Mica also has a brilliant shine that glitters and sparkles. In fact, the name mica is believed to have come from the Latin word mica which means to shine. Mica is responsible for the flashes of light in composite rocks such as granite, gneiss, and slate.

4. ATOMIC STRUCTURE Mica minerals belong to phyllosilicates . The SiO 4 tetrahedron is linked by three corners to the neighbouring tetrahedron forming a sheet. Each SiO 4 tetrahedron has three shared and one free oxygen. The atomic structure consist of two tetrahedral sheet and one octahedral sheet(2:1) Two of these sheet of linked tetrahedral are placed together with the vertices of the tetrahedral pointing inwards.

5. CHEMISTRY The general formula – XY 2 -3 Z 4 O 10 (OH,F) 2 where , X=K, Ca(Na in case of paragonite) Y = Al, Li, Mg , Fe and Z = Si and Al. In mica minerals the Si : Al ratio found to be 3:1.

6. Dioctahedral Micas Trioctahedral Micas Dioctahedral refers to having two of the three available octahedrally coordinated positions occupied . Trioctahedral refers to having all three available octahedrally coordinated positions occupied. Aluminium ion occurs as a cation in octahedral co-ordination Magnesium and Ferrous ion occurs as a cation in octahedral co-ordination Example:- Muscovite, Paragonite Example:- Biotite , Phlogopite , Annite

7. Color Colorless Forms Flakes Massive. Cleavage Perfect parallel to {001}. Lustre Vitreous. Streak White. Twinning Present with twin axis being [310]. Hardness 2.5-3. Specific Gravity 2.77-2.88. Transparency Transparent. Tenacity Elastic. MUSCOVITE (POTASSIUM MICA) Named after the Muscovy principality of thirteenth century Russia , which produced muscovite for use in window panes. KAl 2 (AlSi 3 O 10 )(OH) 2

8. OPTICAL PROPERTIES MUSCOVITE Color Colorless Pleochroism None Relief Moderate positive relief. Optic Orientation X^c = 1 to 4º, Y^a =1 to 3º Z= b Refractive Index and Birefringence n α = 1.552-1.576, n β = 1.582-1.615, n γ = 1.587-1.618. Polarisation color Third order colors. Extinction Straight Optic Axial Ang. 2V= 30-47 o , Biaxial (-). Muscovite Under PPL and XPL Occurrence:- Muscovite is a common mineral found in igneous, metamorphic, and sedimentary rocks. In igneous rocks it is a common constituent of granitic pegmatite, granite, granodionte , aplite , and related felsic rocks. It is somewhat less common in felsic volcanic rocks

9. PHYSICAL PROPERTIES BIOTITE Color Black or dark brown. Forms Flaky, Massive. Cleavage Perfect parallel to {001}. Lustre Splendent . Streak White. Twinning Present with twin axis being [310]. Hardness 2.5-3. Specific Gravity 2.7-3.3. Transparency Transparent to Translucent. Tenacity: Brittle to flexible, elastic. BIOTITE (Magnesium, Iron MICA) K( Mg,Fe )3AlSi3O10(F,OH)2.

10. OPTICAL PROPERTIES BIOTITE Color Colorless Pleochroism Strong; X = gray-yellow, yellow-brown, orange-brown; Y = Z = dark brown, dark green, dark red-brown. Relief Moderate positive relief. Optic Orientation Y = b; X^c = 0-3 o ; Z^c =0-9 o Refractive Index and Birefringence α= 1.565-1.625, β=1.605-1.696 γ=1.605-1.696 Polarisation color:- Masked by its deep intrinsic color Extinction Straight Optic Axial Angle 2V( meas )= 0-25 o , Biaxial (-). Occurence :- Members of the biotite group are found in a wide variety of igneous and metamorphic rocks. Biotite under PPL and XPL

11. PHLOGOPITE Chemical Composition: KMg 3 AlSi 3 O 10 (F,OH) 2 . PHYSICAL PROPERTIES PHLOGOPITE Color Brownish red, dark brown, yellowish brown, green Forms Six-sided prismatic crystals Cleavage Perfect parallel to {001} Lustre Splendent Streak White Twinning On composition plane {001}, twin axis [310]. Hardness 2-3 Specific Gravity 2.7-2.85 Transparency Transparent to Translucent Tenacity: Brittle to flexible, elastic

12. OPTICAL PROPERTIES PHLOGOPITE Color Pale brown, nearly colourless Pleochroism Weak with pale colours ; α= yellow, βand γ deep yellow or brownish red. X = yellow; Y = Z = brownish red, green,yellow Relief Low to moderate. Optic Orientation Y=b; Z^a = 0-5 o Refractive Index and Birefringence α= 1.530-1.590 β=1.557-1.637 γ=1.558-1.637. Polarisation color Third order colors. Extinction Straight Optic Axial Angle 2V = 0-15 o , Biaxial (-). Occurence :- Found in metamorphosed impure magnesian limestone C ommon constituent of kimberlites , and is a minor constituent of ultramafic rocks

13. PHYSICAL PROPERTIES PARAGONITE NaAl 2 (AlSi 3 O 10 )(OH) 2 . LEPIDOLITE K( Li,Al ) 3 ( Si,Al ) 4 O 10 (OH,F) 2 ANNITE KFe 3 AlSi 3 O 10 (F,OH) 2 Color Pale yellow or pale green Rose red. Black, Brown Forms Foliated, massive or disseminated scales. Flat Sheets, aggregates of fine grains Flat Sheets. Cleavage Perfect parallel to {001} Perfect parallel to {001} Perfect parallel to {001} Lustre Pearly Sub-Vitreous, Resinous, Greasy, Pearly. Submetallic to vitreous; pearly on cleavage surfaces . Streak White White white Twinning On composition plane {001}, twin axis [310]. Rare. On composition plane {001}, twin axis [310]. Hardness 2.5-3 2.5 – 3.5 2.5 - 3 Specific Gravity 2.78 2.8 -2.9 3.3 Transparency Transparent to Translucent Transparent to Translucent Transparent to Translucent Some Other Minerals From Mica Group

14. OPTICAL PROPERTIES PARAGONITE LEPIDOLITE ANNITE Color Colourless Colorless to pale pink in thin section. Brown, black Pleochroism None X = almost colorless; Y = Z = pink, pale violet X = brown; Y = Z = dark brown. Relief Moderate positive relief. Moderate positive relief. Moderate Optic Orientation Y ^a; Z = b; X ^ c =50. Y=b; X^ a =900-870 Z^ a =0- 7° Y = b Refractive Index and Birefringence α = 1.564-1.580 β = 1.594-1.609 ° γ= 1.600-1.609 α = 1.525- 1.548 β = 1.551-1.585 γ= 1.554-1.587 α = 1.624 o β = 1.672 ° , γ = 1.672 Polarisation color Third order colors. Third order colors. Masked By Color. Extinction Straight Straight Straight Optic Axial Angle 2V = 0- 40° , Biaxial(-) 2V = 0 -58 . Biaxial(-) 2V= 0- 5 o , Biaxial(-)

15. PARAGONITE LEPIDOLITE ANNITE MARGARITE ZINWALDITE

16. PHYSICAL PROPERTIES ZINWALDITE KLiFeAl (AlSi 3 )O 10 (OH,F) 2 MARGARITE CaAl 2 (Al 2 Si 2 O 10 )(OH) 2 Color Violet, pale yellow or brown in color. Grayish, pale pink, yellow, or green Forms Scaly aggregates; Platy Cleavage Perfect parallel to {001} Perfect parallel to {001} Lustre Pearly Pearly. Streak White White Twinning On composition plane {001}, twin axis [310 ]. On composition plane {001}, twin axis [310]. Hardness 2.5-4 3.5- 4.5 Specific Gravity 2.90-3.02 2.99- 3.08 Transparency Transparent to Translucent Transparent to Translucent Some Other Minerals From Mica Group

17. OPTICAL PROPERTIES ZINWALDITE MARGARITE Color Colourless to light brown Colorless. Pleochroism Distinct; X = colorless to yellow-brown; Y =gray-brown; Z = colorless to gray-brown. Absent. Relief Low to Moderate Moderate. Optic Orientation Y=b; X^a = 88-90 o Z^c =0-2 o Y^a = 6-80 ; X^c =11-130 , Z=b Refractive Index and Birefringence α= 1.535-1.558 β=1.570-1.589 γ=1.572-1.590. α= 1.630-1.638, β=1.642-1.64 γ=1.644-1.650 Polarisation color:- Low order colors. Low order colors. Extinction Straight Straight Optic Axial Angle 2V = 0- 40°, Biaxial(-) 2V = 40 -67 0, Biaxial(-).

18. Uses of Mica Pigment extender in paints and also helps to lighten the tone of colored pigments Sparkly look, it is ideal for toothpaste and cosmetics. Excellent thermal resistance, it may be utilized as an insulator in a variety of electrical devices.( Capacitors, Transistors, Insulators, etc). Mica ( Glauconite ) is used as a fertilizer to provide K. As a constituent of drilling mud used when drilling for oil and gas. Insulator Paint and Pigment Oil and Gas Exploration Rubber Tyres

19. Mica Distribution in India 1. Andhra Pradesh:   Andhra Pradesh is the largest mica producing state of India . In Andhra Pradesh. Nellore, Vishakhapatnam, West Godavari, and Krishna. 2. Rajasthan:   Second largest producer. Bhilwara district located in this belt is the most imported producer of Mica. 3. Jharkhand:   Third largest producer. Kodarma (largest reserve of mica in the world) , Giridih , and Domchanch are the chief collecting centers (located in this belt) where Mica is processed. Apart from this Munger in Bihar also have sufficient mica deposits. The main centres of mica production in this belt are Kodarma , Dhorhakola , Domchanch , Dhab , Gawan , Tisri , Chakai and Chakapathal . 4. Karnataka:  Mica deposits occur in Mysuru and Hasan districts of Karanataka 5. Tamil Nadu:   In Tamil Nadu, Coimbatore, Tiruchirapalli , Madurai and Kanniyakumari districts 6. Kerala:   In Kerala, Mica deposits are found in Alleppey district. 7. Maharashtra:   Ratnagiri in Maharashtra has rich mica deposits. 8. West Bengal:   Purulia and Bankura in West Bengal are known for mica deposits.

20. Bilbliography Books : Nesse William D. Introduction to Mineralogy, Oxford University press. Perkins Dexter, Mineralogy, Third Edition, Pearson Education Limited Rutley's : Elements of Mineralogy, 26th Edition, 1976 Deer, W.A.; Howie , R.A.; Zussman , J. (1966). An Introduction to the Rock Forming Minerals. London: Longman. p. 218.   Links and URLs https://www.mindat.org/min-3090.html https://en.wikipedia.org/wiki/Paragonite https://www.mindat.org/min-2380.html https://geology.com/minerals/lepidolite.shtml microckscopic.ro/minerals/silicates/ phyllosilicates / biotite -thin-section/ https://en.wikipedia.org/wiki/Biotite https://lotusarise.com/mica-limestone-reserves-in-india-upsc/

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