Ne So Silicates
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Transcript of Ne So Silicates
7/17/2019 Ne So Silicates
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NESOSILICATES
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Defnition
Greek, nesos, “island”silicates where the SiO4 tetrahedra
form isolated units
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Defnition
Just like any other mineral containingradicals, the negatively-charged
radicals are held together yintervening cations !in red, at left"
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Olivine
#igh-$ igneous mineral, common in ma%cand ultrama%c rocks& commonly alters toser'entine
(itreous olive green !)g" to lack !*e"+uigranular to 'rismatic hait& 'oor
cleavageO'tics .olorless, ia/ial !0)g, -*e", mod1
high relief !n231", high 5(, δ 2167 !5nd order 8* colors".om'lete solid solution etween )g and *e
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Olivine
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Olivine
*orsterite!)g5SiO4"
*ayalite !*e5SiO4"
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Garnet
+uigranular, euhderal to suhedralhait& 'oor cleavage
O'tics .olorless, isotro'ic, highrelief !n231-319"
.om'le/ solid solutiongeneral formula :;<5Si;O35, where
: is a divalent cation !generally )g,*e, )n or .a" and < is trivalent!=sually :l, sometimes *e0;, $i, or
.r"
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Garnet
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Garnet
Pyrope(Mg3AlSi3O!"
Al#andine($e3AlSi3O!"
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Garnet
Spessartine(Mn3AlSi3O!"
Gross%lar(Ca3AlSi3O!"
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Garnet
Andradite(Ca3$eSi3O!"
&varovite(Ca3CrSi3O!"
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Al%#inosili'ates (AlSiO"
)oderate to high grademetamor'hic minerals formed from
:l-rich source rocks:l in octahedral or a mi/ of
octahedral to tetrahedral sites
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Al%#inosili'ates (AlSiO"
>yanite ? (itreous luish laded taletsw@ single 'erfect cleavage& # 7-
Sillimanite ? (itreous rown to greenclustered 'risms w@ single cleavage dir1
:ndalusite ? (itreous Aesh-red, reddishrown suare 'risms& # 17
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Al%#inosili'ates(AlSiO"
Andal%site Silli#anite
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Al%#inosili'ates(AlSiO"
)yanite
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Sta%rolite
)oderate to high grademetamor'hic mineral formed from
:l-rich source rocksBesinous to vitreous !dull when
altered" reddish-rown to rownishlack C-sided 'risms& commonlyforms inter'enetrating twins
O'tics <ia/ial!-", yellow 'leochroic,high relief !n2317", 5(DE5F-EEF
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Sta%rolite
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Sp*ene
.ommon accessory mineral in felsicigneous rocks and in some
metamor'hic rocksBesinous to adamantine gray, rown,
green, yellow or lack lens crystals&distinct diamond-sha'ed cleavage&# 7-717
O'tics <ia/ial!0", yellow 'leochroic,very high relief !n2516", 5(D5F,
D 613;
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Sp*ene
$itanite