Table 1 Important Properties of Heavy

Name Comp Form/Shape Transparenc Relief Biref XL. Pleochrois Extincti optical Source Dict. Features osition y System m on Chara Andalusit Al2SiO Prismatic Tranp. to Mod Weak Orthorh Prism.c Weak, pale Strt Biaxial – High rank Met. Mod relief, weak brief, strt e 5 Transl. ombic pink to ive Sour extnc, prismatic cleav colourless to colour colourless to pink pleochr pink Apatite Ca5(P Euhedral/Subhed Transparent, Mod Weak hexagon Imperfect Absent Strt Uniaxial – felsic ig rk Prismatic form, mod high O4)3F ral 6sised prism colourless whiten al basal ive relief, weak brief, strt extn xls X– {0001} colorless. polars Cassiterite SnO2 Prismatic/pyrami Translucent/ V high, V high Tetrago Imperfect Occ.Pleochr. prismatic Uniaxial Veins, granite, Form, colour, relief, dal Opaque may nal poor In brown or gr. Show +ive pegmatite extinct., biref Euhedral/Subhed yellowish show reds st. extnc metallifer. Loads ral reddish adamanti alluvial placers brown ne in reflected light Epidole Ca2(Al Prismatic Transparent/ high Mod Monocli Perfect{001 Pleochroic Strt Biaxial – Erosion of Yell, Gr col, weak pleochr , Fe)3 Subhedral Colourless Fe strong nic } in yellowish ive regionally in PPL, high relief mod str OH elongate rich var. may (Fe cont) Imperfect{1 green metamorphosed biref, st.ext in prism. Grain (SiO4)3 euhedral be yellowish 00} rock Circular grains Transparent. Very Isotropic Cubic Absent Absent High rank met rk., Isotopic, high RI, form. full of inclusions Translucent high thermally met rk., absence of cleavage colourless, reg met rk Ca pale pink, G rich, most marine Garnet may sed is dtrital, Sp be yellow, gran Auth origin brown or in marl ooze green Almandin Fe3Al2 e Si3O12 Pyrope Mn3Al 2Si3O1 2 Speseartie Mn3Al 2Si3O1 2 Grasaulari Ca3(Al tte 2Si3)12 Andratite Ca3Fe2 Si3O12 kyanine Al2SiO Blade flakes, Colourless to high Mod Triclini 3sets perfect{100}, less Biaxial, High rank met Colour, grain shape, high 5 sharply angular, blue in c perfect {1010} parting Obidue upto 30 sources frq ass relief, conspic cleavage cleavage patches {001} degree{100} with Staurolite fragment granet, andalusite Monazite (Ce, Prismatic Transparent Very Strong to Monocli Perfect{00 Usually 2– 10 degree Felsic ig rk, sands Form, typically small gr. La, euhedral/subhedr colourless high very nic 1} absent thick with c– axis eroded from Size, v high relief. Close Nd, Pr, al xls or rounded thick grain strong good{100} gr may show granitic hinterland resemblance with sphene PO4) egg shaped show yellow pl but has a lower brief grains brownish colour Rutile TiO2 Prismatic Transparent Exceptio Extreme Tetrago Parallel to Feebly Strt Uniaxial Basic igneous rock Prismatic form, colour, euhedral slightly yellow to red nally v high int nal the length pleochr +ive cleavage, extreme, biref, rounded. brown high colour of the presence of diagonal striae, Striations obscured XI{110} high relief Oblique to prism by total edge due to reflection polysynthetic Mod twinning Sillimanit Al2Si Small slender Transparent , Orthorh Parallel to Absent Parallel Biaxial High rank met source Sillim distinguished from e O5 prismatic grain colorless, ombic the {010} to the +ive Andalusite– strong biref. thick gr. May prism Kyanine– elliman may be appear yellow edge same in PPL but St. extn. or brownish Low RI, high Int colour Sphene CaTiSi Small diamond Colourless to Very Very strong Monoclinic {110} Sometimes Rarely Biaxial Felsic ig rk, met rk– Wedge shaped xl. O5 shaped brown to high same as rutile distinct pleochr in show +ive hbl schist, eu/subhedral freq brownish yellow & complet amphibolite contain inclusion yellow brown e extnc due to dispersi on Staurolite 2Al2Si Irrg euhedral gr, Transparent, High Weak Orthorhombic Prismatic Distinct Prismati Biaxial High rank met rk– Colour, high relief, plecohr O5Fe( serrated edge, gr, pale yellow to parrl to pleochr, pale c +ive assc with sillim, kya, St. extinction, assoc with OH) Surface etch yellowish {010} yellow to section granet other high rank mn brown med yellow show to brown strt extnc Tourrnalin Compl Prismatic eu/ Transparent Mod Mod hexagonal Absent Strongly Straight Uniaxial Acid ig rk blue verity St extinc, strong pleoch e ex Al subhedral xls wide range of to pleochr – ive (indicolite) borosil colour high characterized of icate pegmatite also found in met rk Zircon ZrSiO4 Elongate to Usually Very Very Tetragonal Absent Absent Strt Uniaxial Felsic ig rk, met rk, XI form, transparency, almost equant colourless high strong +ive indicator of reworked inclusions, lack of colour euhedral or transparent sediments also St extnc., strong biref V subhedral xl incl Fraint shades high relief common of yellow or brown

Table 2 heavy variation in the surface sediments of the Indian shelf

Minerals Eastern Coast (Surface sample) Western Coast (Surface sample) (The values indicate the mean percentages based on number counts) Hornblende 11.68 27.97 Pyroxene (Clino) 1.72 2.72 Pyroxene (Ortho) 1.29 1.85 Tremolite/Actinolite 1.53 1.6 Opaque Minerals 37.83 25.02 Chlorite 1.55 1.3 Carbonate 0.97 0.15 Garnet 7.52 1.07 5.14 1.89 0.31 0.58 Andalusite 0.02 0.06 Epidote 4.14 3.24 Clinozoisite 0.48 0.52 Zircon 6.51 1.8 Monazite 2.33 1.16 Rutile 0.82 0.13 Sphene 0.04 0.14 Apatite 1.18 0.03 Biotite 4.94 1.4 Muscovite 5.61 23.48 Toumaline 0.21 0.11 Glauconite 3.12 0.08 Number of samples 118 152

Table 3 3–stage depositional model

1. Initial Stage Supply of Heavy Minerals through rivers and deposition of sand containing disseminated placers by currents, waves etc. 2. Transgressive Stage Erosion and reworking of beach ridges. 3. Regressive Stage Formation of placers in beach is due to waves and long shore current activity giving rise to the present configuration.