Ne so silic a te s 1. Learn more about Nesosilicates, particularly - - PowerPoint PPT Presentation

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Ne so silic a te s 1. Learn more about Nesosilicates, particularly - - PowerPoint PPT Presentation

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3/25/2015 Learning goals Ne so silic a te s 1. Learn more about Nesosilicates, particularly (c o ntinue d ) the structures of garnet, zircon, and kyanite 2. Understand and able to explain the p differences between end members in solid

slide-1
SLIDE 1

3/25/2015 1

Ne so silic a te s

(c o ntinue d )

  • W. K

a nitpa nya c ha ro e n

I mag e so urc e http:/ / www.thiso lde arth.ne t/ I mag e s/ silic ate _struc ture s.jpg

  • Learning goals
  • 1. Learn more about Nesosilicates, particularly

the structures of garnet, zircon, and kyanite

  • 2. Understand and able to explain the

p differences between end members in solid solutions

  • 3. Understand key diagnostic properties of each

nesosilicate mineral

  • Mo stly fo und in me ta mo rphic ro c ks

(e .g . sc hist, a mphib o lite , e c lo g ite ) a nd

Ga rne t X3Y2(SiO 4)3

(e .g . sc hist, a mphib o lite , e c lo g ite ) a nd so me in ig ne o us ro c ks (e .g . pe g ma tite , g ra nite )

  • K

e y mine ra l to inte rpre t the P-T histo ry

I mag e so urc e http:/ / http:/ / www.impro ntaunika.it/ wp-c o nte nt/ uplo ads/ 2014/ 12/ L

  • livina-dalla-c ristallo te rapia-alla-riduzio ne -de i-g as-se rra.jpg
  • The Garnet group is a key mineral in

interpreting the temperature‐pressure‐time histories of the rocks in which they grew such as igneous and metamorphic rocks.

  • Garnets are also relatively resistant to

weathering and useful in defining metamorphic facies of rocks.

  • For instance, eclogite can be defined as a rock
  • f basalt composition, but mainly consisting of

garnet and omphacite. Pyrope‐rich garnet is restricted to relatively high‐pressure metamorphic rocks, such as those in the lower crust and in the Earth's mantle.

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SLIDE 2

3/25/2015 2

  • Hig hly re sista nt to we a the ring

Ga rne t X3Y2(SiO 4)3

Do d e c a he d ro n

  • Symme try: Mo stly iso me tric
  • Cle a va g e : No ne
  • F

ra c ture : Co nc ho ida l

  • Ha rdne ss: 7.5
  • Ge msto ne : Ga rne t
  • Co lo r: Va rie s

I mag e so urc e http:/ / skywalke r.c o c hise .e du/ we lle rr/ mine ral/ g arne t/ 6g arne t-almandite 172f.jpg

  • The general formula of garnet is X3Y2(SiO4)3.

However, Ca2+ cation is appreciably larger than the Mg2+, Fe2+, and Mn2+, resulting in separate mineralogical series of Ca‐rich and Ca‐poor g p garnets.

Ga rne t X3Y2(SiO 4)3

  • T

wo e nd-me mb e rs in so lid so lutio n: Ca-poor

Pyra lspite : X3Al

2(SiO 4)3 Pyro pe -Almandine -S pe ssarite X site : triva le nt c a tio n Cr

3+, Al 3+, F

e 3+

Ca-r ic h

Ug ra ndite : Ca 3Y2(SiO 4)3

I mag e so urc e http:/ / uplo ad.wikime dia.o rg / wikipe dia/ c o mmo ns/ 2/ 24/ Garne t_var._S pe ssartine ,_Putian_City,_Putian_Pre fe c ture ,_F ujian_Pro vinc e ,_China.jpg

g

3 2( 4)3 Uvaro vite -Gro ssular-Andradite Y site : b iva le nt c a tio n Mg 2+, F e 2+, Mn2+

  • Ca‐rich garnet comprise the UGRADITE series

The ugrandite series gets is name from the main minerals in it: uvarovite, Ca3Cr2(SiO4)3, grossular, Ca3Al2(SiO4)3, and andradite, Ca3Fe3+

2(SiO4)3. Site

i X C 2+ Y Al3+ C 3+ F 3+ Th

  • ccupancies are: X = Ca2+, Y = Al3+, Cr3+, Fe3+. The

names based upon the B site occupancy. Grossular‐andradite forms a complete solid solid solution.

  • Ca‐poor garnet form the PYRALSPITE series. The

pyralspite series name is also based upon its pyralspite series name is also based upon its minerals: pyrope, Mg3Al2(SiO4)3, almandine, Fe3Al2(SiO4)3, and spessartine, Mn3Al2(SiO4)3. Site

  • ccupancies are: X = Mg2+, Fe2+, and Mn2+, Y =

Al3+. The names based upon the A site occupancy.

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SLIDE 3

3/25/2015 3

Pyra lspite g ro up Pyro pe

Mg 3Al

2(SiO 4)3

  • Co lo r: re d , purple , b la c k
  • F
  • und in ultra ma fic ig ne o us

ro c ks, e c lo g ite , pe rido tite , se rpe ntinite

I mag e so urc e http:/ / myzo ne -inte rnatio nalg e m1.ne tdna-ssl.c o m/ wp-c o nte nt/ uplo ads/ 2014/ 10/ pyro pe -g arne t.jpg

  • Ca‐poor garnet form the PYRALSPITE series.

The pyralspite series name is also based upon its minerals:

  • pyrope Mg Al (SiO )

pyrope, Mg3Al2(SiO4)3,

  • almandine, Fe3Al2(SiO4)3, and
  • spessartine, Mn3Al2(SiO4)3.

pyrAL spite g ro up

AL

ma ndine F e 3Al

2(SiO 4)3

  • Co lo r: re d , b ro wn, b la c k
  • F
  • und in me ta mo rphic ro c ks:

sc hist

I mag e so urc e http:/ / uplo ad.wikime dia.o rg / wikipe dia/ c o mmo ns/ c / c 9/ Almandin.jpg

  • Ca‐poor garnet form the PYRALSPITE series.

The pyralspite series name is also based upon its minerals:

  • pyrope Mg Al (SiO )

pyrope, Mg3Al2(SiO4)3,

  • almandine, Fe3Al2(SiO4)3, and
  • spessartine, Mn3Al2(SiO4)3.
slide-4
SLIDE 4

3/25/2015 4

pyra lSPite g ro up

SPe ssa rite

Mn3Al

2(SiO 4)3

  • Co lo r: re d , o ra ng e , b ro wn
  • F
  • und in me ta mo rphic ro c ks,

pe g ma tite s

I mag e http:/ / 40.me dia.tumblr.c o m/ 5f683f6f91b c b 9ffa7b 8052227f3fb 0e / tumblr_ndo 4wkwjc e 1tfq o l2o 1_500.png

  • Ca‐poor garnet form the PYRALSPITE series.

The pyralspite series name is also based upon its minerals:

  • pyrope Mg Al (SiO )

pyrope, Mg3Al2(SiO4)3,

  • almandine, Fe3Al2(SiO4)3, and
  • spessartine, Mn3Al2(SiO4)3.

Ug ra ndite g ro up Uva ro vite

Ca 3Cr

2(SiO 4)3

  • Co lo r: b rig ht g re e n
  • Ra re g a rne t
  • F
  • und a s sma ll c rysta ls

a sso c ia te d with pe rido tite , c hro mite , se rpe ntinite , kimb e rlite

I mag e so urc e http:/ / http:/ / www.mindat.o rg / pho to s/ 0307363001306726370.jpg

  • Ca‐rich garnet comprise the UGRADITE series

The ugrandite series gets is name from the main minerals in it:

  • uvarovite Ca Cr (SiO )
  • uvarovite, Ca3Cr2(SiO4)3,
  • grossular, Ca3Al2(SiO4)3, and
  • andradite, Ca3Fe3+

2(SiO4)3.

slide-5
SLIDE 5

3/25/2015 5

uGRa ndite g ro up

Gro ssula r

Ca 3Al2(SiO 4)3

  • Co lo r: c inna mo n b ro wn, g re e n
  • F
  • und in c o nta c t me ta -

mo rpho se d lime sto ne s with d io psid e , wo lla sto nite

I mag e so urc e http:/ / http:/ / www.dako tamatrix.c o m/ imag e s/ pro duc ts/ g ro ssular34047e .jpg

  • Ca‐rich garnet comprise the UGRADITE series

The ugrandite series gets is name from the main minerals in it:

  • uvarovite Ca Cr (SiO )
  • uvarovite, Ca3Cr2(SiO4)3,
  • grossular, Ca3Al2(SiO4)3, and
  • andradite, Ca3Fe3+

2(SiO4)3.

ug rANDite g ro up

ANDra dite

Ca 3F

e 2(SiO 4)3

  • Co lo r: ye llo w, g re e n, b la c k
  • F
  • und in de e p-se a te d ig ne o us

ro c ks, se rpe ntine s, sc hist

I mag e so urc e http:/ / www.dako tamatrix.c o m/ imag e s/ pro duc ts/ andradite 34231b .jpg

  • Ca‐rich garnet comprise the UGRADITE series

The ugrandite series gets is name from the main minerals in it:

  • uvarovite Ca Cr (SiO )
  • uvarovite, Ca3Cr2(SiO4)3,
  • grossular, Ca3Al2(SiO4)3, and
  • andradite, Ca3Fe3+

2(SiO4)3.

slide-6
SLIDE 6

3/25/2015 6

SiO 4

4- te tra he dro n

Biva le nt: F e 2+ , Mg 2+, Mn2+ T riva le nt: F e 3+, Al3+, Cr

3+

Oc ta he dro n

Mo difie d fro m http:/ / www.uwg b .e du/ dutc hs/ pe tro lo g y/ Garne t%20S truc ture .HT M

  • Garnet is one of the most common

nesosilicates but it has a complex structure.

  • Bivalent cations and SiO4 forms tetrahedral

sites (yellow orange) while trivalent cations sites (yellow, orange) while trivalent cations and oxygenn forms octrahedral sites (blue).

Pyro pe

Mg 3Al2(SiO 4) 3 Co mple te so lid so lutio n se rie s

Spe ssa rite

Mn3Al2(SiO 4) 3

Alma ndine

F e 3Al2(SiO 4) 3

0 10 20 30 40 50 60 70 80 90 100

v v v v v v v v v

Co mpo sitio n (Mo le c ula r %)

Mo difie d fro m https:/ / www4.nau.e du/ me te o rite / Me te o rite / Bo o k-Glo ssaryG.html

  • Pyrope‐almandine and almandine‐spessartine

form complete solid solutions.

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SLIDE 7

3/25/2015 7

Co ng lo me ra te

  • F
  • rme d in silic a te me lts a nd o fte n

c o nsiste d o f ra re e a rth e le me nt (RE )

Zirc o n ZrSiO 4

c o nsiste d o f ra re e a rth e le me nt (RE )

  • (Zr

1–y, R

E

y)(SiO 4)1–x(OH)4x–y

  • F
  • und in se dime nta ry, ig ne o us, a nd

me ta mo rphic ro c ks e .g . ma fic ro c ks, pe g ma tite s, c a rb o na tite s

  • E

c o no mic so urc e s o f ha fnium, zirc o nium

I mag e so urc e http:/ / www.zac ktrave l.c o m/ wp-c o nte nt/ uplo ads/ 2013/ 05/ papako le a_b e ac h_hawaii_6.jpg

  • Zircon forms in silicate melts with large

proportions of rare earth elements (RE). For example, hafnium is almost always present in quantities ranging from 1 to 4%.

  • Zircon usually occurs as a primary crystallization

productsin igneous rocks , in metamorphic rocks and as detrital grains in sedimentary rocks. Large zircon crystals are rare.

  • Due to its hardness durability and chemical

Due to its hardness, durability and chemical inertness, zircon persists in sedimentary deposits and is a common constituent of most sands. Zircon is rare within mafic rocks and very rare within ultramafic rocks

Zirc o n ZrSiO 4

  • T

he Olde st mine ra l o n E a rth fo und a t the Ja c k Hills in Austra lia

  • Ra dio a c tive de c a y o f ura nium

(ha lf-life : 4.5 b illio n yrs)

  • 4.4 b illio ns yrs

the Ja c k Hills in Austra lia

I mag e so urc e http:/ / i.live sc ie nc e .c o m/ imag e s/ i/ 000/ 062/ 884/ iF F /

  • lde ast-Z

irc o n.jpg ? 1393022478

  • Zircons contain trace amounts of uranium and

thorium and can be dated using several modern analytical techniques.

  • Because zircons can survive geologic processes

like erosion, transport, even high‐ , p , g grade metamorphism, they contain a rich and varied record of geological processes.

  • Currently, zircons are typically dated by uranium‐

lead (U‐Pb) techniques

  • Zircons from Jack Hills in the Narryer Gneiss

Terrane Yilgarn Craton Western Australia have Terrane, Yilgarn Craton, Western Australia, have yielded U‐Pb ages up to 4.404 billion years, interpreted to be the age of crystallization, making them the oldest minerals so far dated on Earth.

slide-8
SLIDE 8

3/25/2015 8

  • Co lo r: Va rie s
  • Symme try: T

e tra g o na l

Zirc o n ZrSiO 4

Symme try: T e tra g o na l

  • Cle a va g e : Po o r
  • F

ra c ture : Co nc ho ida l

  • Ha rdne ss: 7.5
  • Ge msto ne : Zirc o n

I mag e so urc e http:/ / www.jo hnb e tts-fine mine rals.c o m/ jhb nyc / mine ralmuse um/ 49518de t.jpg

Re me mb e r this?

  • The crystal structure of zircon

is tetragonal crystal system.

  • The natural color of zircon varies between

colorless yellow‐golden red brown blue and colorless, yellow golden, red, brown, blue, and green.

Alumino silic a te Al

2SiO 5 Po lymo rphs

SiO 4

4- te tra he dro n

Al-O Oc ta he dro n

4

Mo difie d fro m: http:/ / rub y.c o lo rado .e du/ ~smyth/ min/ alumino s.html

K ya nite

T ric linic

Anda lusite

Ortho rho mbic

Silima nite

Ortho rho mbic

  • Kyanite, andalusite, and silimanite are

polymorphs, which mean they have the same chemical formula but have distinctly different

  • structures. Kyanite is tricilnic while Andalusite

y and Silimanite are orthorhombic.

  • Andalusite is the least dense of this group,

having been formed under the lowest pressure, whereas kyanite is the most dense d f i d h hi h due to formation under the highest pressure

  • conditions. This is consistent with the closely

packed structure of kyanite.

slide-9
SLIDE 9

3/25/2015 9

Alumino silic a te Al

2SiO 5 Po lymo rphs

I mag e so urc e http:/ / www.mine raltivadar.hu/ Mine ral/ kyanite -b razil-DS C07490.jpg

  • Changing in pressure and temperature

conditions affects changing in structures and Al‐coordination. Kyanite is a high pressure phase of aluminosilicate while Silimanite is a p high temperature. Andalusite is a low pressure phase at variable temperatures.

  • Hig h pre ssure pha se
  • F
  • und in me ta mo rphic ro c ks e .g .

K ya nite Al

2SiO 5

F

  • und in me ta mo rphic ro c ks e .g .

sc hist, g ne iss a nd g ra nite pe g ma tite

  • Symme try: T

ric linic

  • Cle a va g e : Pe rfe c t o n {100}
  • Co lo r: usua lly b lue due to F

e , T i

  • Ha rdne ss: 4-5

I mag e so urc e http:/ / www.mine raltivadar.hu/ Mine ral/ kyanite -b razil-DS C07490.jpg

  • Kyanite is a metamorphic mineral that occours

in schists, gneisses and granite pegamatites.

  • Kyanite occurs as bladed and tabular triclinic

crystals. y

slide-10
SLIDE 10

3/25/2015 10

  • L
  • w pre ssure pha se
  • F
  • und in me ta mo rphic ro c ks e .g .

Anda lusite Al

2SiO 5

F

  • und in me ta mo rphic ro c ks e .g .

ho rnfe ls

  • Symme try: Ortho rho mb ic
  • Cle a va g e : Pe rfe c t o n {110}
  • Co lo r: White , pink, vio le t, g ra y, o ra ng e
  • Ha rdne ss: 7.5

I mag e so urc e http:/ / www.mindat.o rg / pho to s/ 0457416001251465223.jpg

  • Andalusite is a common metamorphic mineral

which forms under low pressure and low to high temperatures. The minerals kyanite, andalusite, and silimanite, each occurring , , g under different temperature‐pressure regimes and are therefore rarely found together in the same rock.

  • Because of this the three minerals are a useful

l h l id if h tool to help identify the pressure‐temperature paths of the host rock in which they are found. An example rock includes hornfels.

  • Hig h te mpe ra ture pha se
  • F
  • und in me ta mo rphic ro c ks e .g .

Silima nite Al

2SiO 5

F

  • und in me ta mo rphic ro c ks e .g .

sc hist, g ne iss a nd g ra nulite

  • Symme try: Ortho rho mb ic
  • Cle a va g e : Pe rfe c t o n {010}
  • Co lo r: Gra y, white , ye llo w, b ro wn
  • Ha rdne ss: 6-7

I mag e so urc e http:/ / mindatnh.o rg / g alle ry%20pho to s/ S illimanite %201.jpg

  • Silimanite is an index mineral, indicating high

temperature but variable pressure. Example rocks include gneiss, schist, and granulite.