American MineralogistVol. 57, pp. 103-129 (1972)

THE EFFECT OF CATION SUBSTITUTIONS ON THEPHYSICAL PROPERTIES OF TRIOCTAHEDRAL

MICAS

Rosonr M. Hezrw AND DAvrD R. WoNns,l Department of Earthand PlanetarE Sciences, Massachusetts Institute of Technology

C ambridge, M assachusetts 02139

ABsrRAcr

Unit cell dimensions and refractive indices have been determined for synthetichydrous trioctahedral micas in which each of Co'*, Cu'*, Fe'* and Ni* completelyoccupies the octahedral sites. Zn- and Mn-micas with excess aluminum have also

been synthesized, but syntheses of pure Zn'*, Mn'*, Cd'*, and Pb'* micas were

not successful. Tetrahedral substitutions ,of B3*. Fe"*, and Ga,s* for Al"* and Ge*

for Sia*, and interlayer cation substitutions of Rb*, Cs*, NIT.*, and Na* for K*provide additional data on linear relationships that exist between ionic radii(Shannon and Prewitt) and unit cell edges, and between (ionic radii)" and unit

cell volumes of these micas. The influence of substitutions on the unit cell are

such that octahedral substitutions predominantly affect the a-dimension, inter-layer substitutions the c-dimension, and tetrahedral substitutions affect bothdimensions.

Tetrahedral and interlayer cation substitutions of a wide range of ionic radii

were found to form stable micas. However, octahedral cations of greater than

0.78 A average ionic radius do not form stable trioctahedral micas of the formKB"'* AISLO'. (OH),. The instability of zuch micas is shown to be due to the

misfit of smaller tetrahedral layers onto a larger octahedral layer. The composi-sition of natural biotites are explained on the basis of this model. In addition,quantitative predictions of the amount of Fes* in octahedral and tetrahedralpositions in synthetic annite were made, and have been confirmed by M6ssbauerand analytical chemistry techniques. A nomogram is constructed from which, forany given composition of a hydrous trioctahedral mica, the relative stability of

the mica may be determined.

Inrnouucrrox

Trioctahedral micas are subject to a wide variety of cation substi-tutions. Several authors have demonstrated that such substitutionshave a profound effect on both the physical properties and the stabili-ties of these layer silicates (Hatch et a1.,7957; Wones, 1963b; Klings-berg and Roy, 1957). A list of several recent studies on synthetichydrous trioctahedral micas is given in Table 1. While data are nowavailable for a dozen such mica end-members, there has been littleattempt to systematically examine changes in mica properties withcomposition. The present study is an attempt to define quantitatively

1 Present address: U. S. Geological Survey, Washington, D. C.20242

103

HAZEN AND WONES

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SUBSTITUTIOA|8 IN'I MICAS 105

the effects of a wide range of cation substitutions on the physical

properties of hydrous trioctahedral micas.

Mrca, CouPosrrIoNS Srulrno

The hydrous magnesian trioctahedral mica, phlogopite-KMggAlSigOro(OH)z, was used as the reference composition in this study' At-tempted 100 percent octahedral substitutions for Mg" included Mn2.,Co*, Ni'*, CtJz',2L2*, Cd2*, and Pb2-. Data of Wones (1963b) on the

Fe'* mica annite, and synthetic biotites on the join phlogopite-annite,have also been employed. Tetrahedral cation substitutions were Ga8*,Fe'*, and B3* for Al3*, and Gen* for Si-n; while substitutions into theinterlayer cation K. position include Rb*, Cs*, Cu*, and Ag-. In addi-tion, Na* phlogopite data of Carman (1969) and NHr* phlogopite data

of Eugster and Munoz (1966) have been used in this study. Finally, anumber of double 100 percent cation substitutions into the phlogopitestructure were studied, including ferriannite-KFer2*p.a*g'tO.o(OH)z(data of Wones, 1963a), nickelous ferriphlogopite-KNisFeSiaOro (OH) z,cobaltous ferriphlogopite-KcogOro (OH) z, and sodium-zinc phlogopite-NaZnaAlSisOto(OH)r.

ExpnnrlrnNrer, TncrrNrqun

4 h. .y-alumina was prepared by heating AICL'6H,O for t h' at 750"C' The

silica glass was cleaned both magnetically and in acid, and fired at 800"c for 2 h.

before using. Kro . 2sio, was prepared by D. R. Wones from cleaned sioe glass

and KHCO" after the method of schairer and Bowen (1955). starting materials

of five types were used:

1) Oxide Mix

2) K'Si,O" Plus oxides

3) KAIS;OB gel plus E'* oxide or hydroxide

4) KFeSLO" gel plus E'* oxide or hydroxide

5) Mica gel

All gels were prepa.red by titration of standardized nitrate solutions. The solution

mixes were dried and fired as described by shaw (1963). oxide mixes were pre-

pared by weighing and mixing dried oxides or hydroxides, and then grinding in

an agate mortar until optically homogeneous.charges were sealed with excess and deionized and distilled water, or 30 per-

cent IIpOg solution in Au or Ag*Pdr * in X * in capzuIes. In several runs oxygen

fugacities were controlled by the solid buffer technique of Eugster (1957).

Standard cold seal hydrothermal plessure apparatus was used in all runs (Tuttle,

HAZEN AND WONES

1949). Pressure measurements are believed accurate within L per cent, and theerror in temperature is within +8"c. All runs were rapidly quenched (2 min.) ina cool water bath. A partial list of synthesis experiments will be found in Table B.

accurate to within -r.0005. All X-ray diffraction and optical work was performedatroom temperature (24. -+. l.C).

UNrr Cpr,r, Penelrprnns

lM unit cell dimensions and volumes, as well as morecurar weightsand calculated densities, for synthetic hydrous trioctahedral micas of

TABLE 2 . Chemica ls used in s ta r t ing mater ia . l - p repara t ion

Chemica-Ls used in ox ide mix p repara t ion

106

Formulae

S i O 2 g l a s s

G e o 2 ( t r i g o n a l )

A I C I 3 . 6 r i 2 0

Fe 203

Bzo3

M9o

MnO

C o S O 4 . 7 H 2 0

N i O

Cuo

ZnO

cdo

N i ( o H ) 2

N H 4 ( O H )

Krico3

K ( O H )

ogro

Cu 20

M a n u f a c t u r e r ( & c r a d e ) *

c o r n l n g ( I u m p c u l l e t )

F i s h e r

l '{a I-Linkrodt

t f sner

u . 1 . S a K e r

F i sher

K & K

Ma I 1 ink rod t

M a t h e s o n , C o l e m a n & B e l 1

Ma I - I ink rod t

Baker & Adamson

Baker & Ad - , rson

K & K

J . T , S a K e r

, f . T . B a k e r

J . T . B a k e r

K & K

F i siler

Lot Number

7 9 4 0

7 8 6 6 0 4

I 5 9 6 l X

7 62942

3 9 3 1 5

7 8 7 6 9 9

- t 0 8 6 8

C B 9 I 8 N X 3 4 5

x 4 0 5 8 8

8 3 5 4

A.24 4x3 6 4J

1 6 2 I 4

2 4 0 3 7

2 1 , 5 3 7

J _ 4 8 9 0

r 7 6 9 2

SUBSTITUTIONS IN MICAS

m ^ D t F t . ^ h + i n r r a . l

Addi t iona l chemica ls used in ge l p repara t rons

107

Formuale

" L u d o x " * *

A9 Meta l

Cu l4etal

z n M e t a I

P b M e t a l

c a M e t a I

KNO3

N a N O 3

RbNo3

C s N O 3

M s ( N o r ) ,

14n (No, ) 2

A I ( N * o - ) ̂

c r ( N O 3 ) 3

. 6 t i 2 0

. 9 H 2 0

'9H20

Lot Number

7 r 0 9 6

N - 0 2 3

4 0 6 7 I

n . d .

3 0 I 5 8

? ? ? 7 q

1 8 0 8 8

7 824

37 0L2

27 35'1

26829

7 95204

M a n u f a c t u r e r ( & G r a d e ) *

D u p o n t ( H i q h S i I i c a )

F i s h e r

Baker & Adamson

Merck

F i s h e r ( 8 / I 0 0 0 " f o i l )

J . T . B a k e r ( 9 9 . 9 9 9 u )

J . T . B a k e r

J . T . B a k e r

K & K

K & K

Ma I l ink rod t

M a l l i n k r o d t ( 5 0 g s o l u t i o n )

Ivla II inkrodt

MaI I ink rod t

*AI - [ chemfca ls reagent g rade un less no ted '

* * D u p o n t L u d o x w a s a n a l y z e d b y F ' F r e y ' S o l i d s a f t e r

i n c r u d e b y w e i g h t s i o 2 = 9 9 ' 0 8 a n d N a ' o = r ' 0 ? '

d r y i n g a n d f i r i n g a t 3 0 0 " C

this and other studies are listed in Table 4. AII parameters were refinedusing at least twenty equally-weighted X-ray powder reflections, ex-cept for Rb* and Cs* micas for which only three broad peaks wereobserved. smith and Yoder (1956) have shown that trioctahedralmicas often possess an ideal pseudo-trigonal unit cell, defi.ned by a* =

b,*/(8)r' and door : cm'sin F*. Of the micas examined, only sodiumand boron phlogopites depart appreciably from these ideal relations.

Crowley and Roy (1960) have demonstrated that pressure of forma-tion does not signifi.cantly affect unit cell parameters of phlogopite.

Similarly, synthetic micas exarnined in this study showed no systema-tic variations of cell parameters with temperature or pressure of cry-stallization. However, Eugster and Wright (1966) have noted that thephysical properties of boron phlogopite appear to vary with tem-perature and pressure of formation. Also, Carman (1969) has clearlydocumented the tendency of sodium phlogopite to hydrate below 80'C.

r08 HAZEN AND WONES

Thus, sodium and boron phlogopite once again depart from the idealcase. It should be noted that sodium and boron phlogopites have thesmallest cell dimensions of all micas studied.

Oprrcer, Dererndices of refraction for synthetic hydrous trioctahedral micas of this

and other studies are found in Table 5. Due to the psued.o-trigonalhabit of these micas, "t = F, and thus two refractive indices are definitive.Other optical parameters considered include birefringenc e B : ,y - aand the observed mean refractive index n : t/iV : (2t * a)/8.While synthetic crystallites seldom exceeded 20 p in size, thus making

aABrE l . V ica Svnth

u icas o f the fon R+Mg3Als iOtO(oH)2s u b s t i t D t i n g f o n i c l 'J+fr !- ladrus (Ao ) Fun +

K 1 . 3 8 x # Le b * I 4 9 x * r o s

I t i 9 8c s ' I ? o t i * L o d

x + 9 9A 9 1 . 1 5 l { * 4 6

M # 9 0

c u * 0 . 9 6 t i k r 2 2

\ g + 2 o , 7 2 a u * lu^+2 o g3 lr*13

2

8 0 0

7 A Ar 0 0

7 4 03 0 0

3 1 05 0 0

6 3 0

Dura t ion s ta ! t in9(hours) Mater ia ls Produc ts

7 0 g e l l 0 0 t p h l o g o p i t e

f40 Se1 tu -ph togop i re , Fors te r i te , ! tuAIS i2O6

3 4 0 g e } d o . p l u s g l a s s

140 geL Cs-ph logop i te , Fors te r i te , E csA ls i2o6

349 ge l lo rs te l i te , csAts i to6 & g lass

4 8 g e l S l t v e r U e t a t E g ] a s s

72 YgAIS i3 S i l ver Meta l , ch lo r i te & g tassqer paus

A92o

96 Ox ide U ix Cu2O, Ta lc & unknown phase

Micas o f the fom (R3+2Ats i3o ]o(oH)2

co+2 o 745 :r+tt4

s R + 1 2

s R + 3 4 -

r , i t2 o 69 :4!76

1r+15

c u + 2 o ? 3 l r t 2 9

11+49

\t j71

z ^ ' 0 . 7 5 i l # 8

M + 1 7

10 ge t 10Oc Ph logop i te

95 Ox ide Mix & o-Mn2o i ; l -h2ot e sahad inex 2 s i 2 o 5 g e l

2 1 6 X e d u c e d M n O r M n ( O H ) , & g l a s sox ide U ix

120 " Tephro i te , xa ls iL i te & Leuc i te

1 2 0 S . 1 M n i o t ) z 6 l a n g a n o p h y l l j t e

72 t ' ] -Mn2o3 & Sdn id ine

96 Reduced ge l Braunr re 6 san id ine

I fs ge l

4 8 c o ( o l ) 2 + 1 0 0 8 c o b a l t o u s p h l o g o p i t e

4 8 c o ( o H ) 2 + 1 0 0 i C o b a l t o u s p h l o s o p i t e

48 sR) ]? Coo, co Ol iv ine r leuc i te

145 ox ide l l i x 100S Nicke lous Ph logop i te+ x2s i2o5 9e I

48 N i (oH) 2+ I00S N lcke lous Ph logop i te

I 2 0 g e l 8 0 3 C u p r i c P h l o g o p i t e , g l a s s a n d m i n o run ident i f ied phase

9 6 g e l 5 0 c c u p r i c P h l o g o p i t e , g l a s s a n dun ident i f ied phase

215 ge l cupr ic Ph logop i te , Cu-Py loxene &Suscov i te

I45 ox ide n ix w i l l .en i te , {a ls i l i te , & teuc i terx2s1205

2I5 or ide n ix V i l len i le , X ica E minor Leuc i teE K r S i 2 0 q

M + I 8

] r l r 9i l+3 2-\1* 62I r + 8 5

8 0 04 5 0

2 8 0

326

6 0 31 2 55 4 0

1 5 0

^ i { i cas o f the fo rn xR3+zAts i3o to(oH)2

vrgL3 500 336 "

, , i=z i ln (oE) 2 & Manganophy l l i te

i r X 9 2 3 5 O O 3 3 6 S . I T e p h l o i t e , K a l s i l i t e e l e u c i t e

r i l173 600 96 r4no prus Tephro i re / (a ts i t i te & leuc i te

7 5 0

7 1 0

8 8 0

5 0 0

6 0 0

7 0 3

260

6 0 0

280

1 .2 ,l .4 ,

S h a n n o n a n d P r e w i t t ( 1 9 ? 0 ) .

A11 runs a t P = 2 kbar t i2o un less no ted '

P = L . 0 k b a ! C H r ' .P = 0 . 2 k b a r H 2 O .

SUBSTITUTIOIVS IN MICAS 109

c d -

Subst icu t ing Ion icca t ion lad ius (A ' )

P b + z 1 . r B get Pb4 S iO6 E un lnown Phase

SeI X2Pb4s igo2t , san id lne & Pb3o4

Du!a t ion SLar t rng

Run * T( 'C !3 ' ) (hours ) Mate l ia ls Produc ts

M*61 725 7z ge l w i l len i te ' (a ls i l i te & leu ' iLe

M*94 530 so ge l w i l len i te ' H ica & l€uc i te

! * l 0 l 5 o o 2 9 o g e l w i l l e m i t e ' M i c a & L e u c i t e

M{9 600 145 ox ide n ix cd-o l i v ine & leuc ice

E K25 i2o5

M+22 385 360 Reduced cd-o l i v ine & san id ine

ox ide n ix

0 . 3 9

0 . 1 2

c " + 3 o . 4 7

r e + 3 o , 4 9

c . + l ( r v ) n . d .

s i + 4

M * s 7 5 5 0 2 9 O

M * 6 5 4 r 0 1 7 0

u + 4 4 7 0 0

14172 410

M s L 8 0 0

u * 6 3 7 2 5

M i c a s o f t h e f o r n K M g 3 R + 3 s i 3 o t o ( o H ) 2

M*I 8Oo 7o ge l 1009 Ph logoPi te

M*30 603 I2o ox ide Mtx qo3 soron Ph losoPi t€ ' s rass

& R25 i2o5

M+108 120 f2o ox ide Mix 95& Boron Ph logoPi te

& (2s i2o5

u+45 310 4s geL 40& Gal l tw Ph logop i te ' e2o3 '

unknown Phase E g lass

M* lo9 720 120 Se l lOOt Ga l l iun Ph logop i te

M* IOO 5Oo 265 Ox ide Mix 1008 Fer t i -Ph logoPi te

& (2s i2o5

14+107 72o 120 ox ide { i x 1008 re r r i -Ph logopr te

t ( ' s i 2 o 5

u* l r t 590 2r5 o* i6 " u r i toOE Fer r i -Ph logoPi te

& (2si2o5

96 gel cr2o3, Forster i le E unknown phase

3l gel ct2o3, Forstei i te 6 slass

EicEs of the fornr xus,alna+4oto(on),

7o ge l loo t Ph logop i te

75 ox ide Mi { 100? Ge-Ph logop i tao . 2 60 . 4 0

0 . 7 2 M * 1 0 0 5 0 0

u + 1 0 7 1 2 0

' u + t 1 L 6 9 0

M * 1 2 1 7 0 0

u icas o f the fo rn (R3+2fes i3o to(o t r )2

2 6 5 O x i d e M i x& R 2 S i 2 o 5

120 ox ide $ ixE KZSi2O5

215 ox ide u ix& x 2 s i 2 o 5

loos Fer r i -PhIogop i te

100? F€r r i -Ph logoPi te

lOOS Fer r i -Ph logoPr !e

lOOs N icke lous Fet f , i_Ph lcgoPi !eN i + 2 0 , 6 9

co+Z o-;a5

Ni (o i l ) , &(FeS i -b ^

u i l 1 2 7 7 0 0 2 4

2Il determination difficult, all observed 2v - 0o. Micas are colorlessexcept for those containing cations of the transition metal series.Intense pleochroism was observed only in iron-bearing trioctahedralmicas, whereas faint pleochroism was noted in cobalt and copperphlogopites.

A useful, but seldom used, optical property is the specific refractiveenergy K, defined by K : fr - L/p where 11 is the mean refra,ctiveindex and p the density. Gladstone and Dale (1864) demonstrated that Kfor liquids may be calculated from the formula: K : hr(P'/100) +kr(Pr/100) * etc., where kr, hr, etc. are the specific refractive energiesof the components of the liquids and P1, P", etc. are the weight per-

centages of these components. H. W. Jatre (f956) applied the mle of

Gladstone and Dale to minerals, treating oxides as components of the

minerals. Ja,ffe obtained reasonable agreement between observed and

c o ( o H ) , & l o o s c o b a l l o u s l e r r i

I-i" '.-"'

+l

HAZEN AND WONESl l 0

r3 @ 4n @ 66 6

H d " 3 '0 0 & 4l ^ t r ^

m l

1 6 l - @ i N @ 3 d @ Nd > l r r e o d < 4 n o

o-U{ N N N o o o o o o

- N< N n @ N O O N i s i @ 9 i @+r +r +l +t +r +t +l +t +t +t +t +t +t +t +l +l

s 9 < 4 N $ < @ { @ o $ @ o v o @ @ r - -h 4 6 + < 4 4 4 4 4 n . 4 4 d O n n o D o O

o o r d o oE l o o o r 6 6 6 6 6 O 6 - , O O O O 6 O 6 6 O o

@ l 6 o o 6 O O O O q 6 6 C O 6 O 6 6 6 O O O oi l d n

6 4 n i r N N N < < O 4 N d @ m N 6o o o o o 4 4 0 0 0 0 0 0 t o o o o o o oo o o o o o o o o o o o o o o o o o o o o

^ l + r + r + r + l + t + t + r + t + t + j + t + l + l + l + t + t + t + t + t + t + lo . l d g < g o o r @ i $ @ r s i N m N r r4 l i d n 6 < 6 o + $ @ @ r i i o i 4 d 6 i 6 o- l o o o o I $ @ O O N N d m O N O O O N o N N

E l o o o 6 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0o l d i d d d d d d d d d i d n d i d d d d d

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n l r r r 6 < o @ N O O N i d @ r i N O o N O < F d. o l 6 6 6 r O i i o o 6 6 - , o 6 i i o o o o o o a> l s < s 3 Q 4 n n n s s q s { h n n 4 4 n n 4 4

N N Q v o N H o N N 6 N H d N i o oo o d o o N N O O O O O O O O O O O O o o

, o o o o o o o o o o o o o o o o o o o o oo_l +l +l +l +r +l +t +t +t +t +l +t +t +t +t +r +t +l +t +t +l +l< l $ @ < o s o o N n @ < r @ c i N o s n N- l O O O O N < o $ I r r , O o $ $ m $ I r @ t

- I N N N N N N O N N d i r d N N O M N N N N N Otr I

A l o o o 6 q o q o o 6 o c q q q o 6 o 6 o 6 6

i d @ @ H d 4 o i i l d @ N h r oo o d o o H H o o o o o o d o o o o o o d

. o o o o o o o o o o o o o o o o o o o o o

o | +r +l +l +t +t +l +l +t +r +t +t +t +t +l +t +t +t +t +t +l +l4 1 4 < 3 4 i o H o r s o i r 6 o o o @ o- l d d d @ i < r I s o o . o o o 6 o o < < n r

_ l m o m N m o o o o o N r c t o l m s o o o o m o ot r l ' ' . | .

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1 1 1SUBSTITATIOI{S /N MICAS

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e l o o o o o o o o o o o o o

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h {o E o

o s 4 & b q !! ^ ^ o . i o

! ! d H d t 6b b a m ! E a

. b 5 0 r b o r? l o q i 6 e ! q ! t o

_ 9 t H O q q i

6 6 1 - o "

f f b f .t l q ! d o a o @ q o b 6 J 6 o i o r f i

t o l o o E o o o o i i E 6 o o o q d d o o N dc H l i q € ! i ; E F i d . d N H b d . d i a I E d i? o l + o o o + + o o + + d + * 5 * d * . d + o +q E I E 3 > U T E B B I E V T E H E X E E = B E E

o

3 F 3o Q ot q

4 0 4

o Q o! !i l n IX N X

q !B O

E

o!ts

o

o

o

!

< d d 6 r dF d N N No O O . o O r o $ +

. " O . ' O . o oo o o .

+ + + + + q + + q t + +

o d o H r o. i @

E O d F F

d d a i E 4 4 4

b o o 6 6 6 0 < 6 t ss 6 N N N m < 4

o 4 n 6 t o € 9 r r

d i d d i d d i d d

i d N i N o i o o o

N i O < N N N Nd i o o o o

r i 6 6 6 h o o 6 n N o o o 6 @ N N 9 @ O Or o o 6 @ t s o o

o 4 h n 4 a F @ n o 6 n

H i i l i i i i 4 d d d i d i i i l i i i H i i i

q r r y o o N N N N s N N 6 N i o n n so o o o i d o o o o o o o o o oo o o o o o o o o o o o o o

o o @ o i o e n 6 0o a d @ < s n .

6 O 6 6 n 6 6 6 9 € . h 4 6 6 E S s h t s r r

d l i i d i i i i i i d H i d i E d i i i _

+ 6 0o i i - o t - o t

' o t- o 0 t h t h t E l

N N N N N i + + N N t N+ + + + + + 6 l o l + + | +

I O O O 4 l 9 l k l m o3t 8t Et 6t fll 3t tl

F I. : l{ l n € d o r d i no . l i i i N @ d a o' d t c t o o> < t . ,o l o o o o o o o oo l + + + + + + | |

, n i o i o o @ No t r r Fq l n n ho t . . .

a l i i i i d i a i

, F i o s n 6 r bo t m o s

i ! t o oo t .

6 l o o o

+ + +d t 4 t o lz t E t o l

o

! l a l. i t o lo t i lo t 4 lq oE I o Io t E lO I V I

SUBSTITUTIOT{S lN MICAS

calculated fi in this manner. However, it is interesting to note thatthe calculated d for hydrous silicates considered in Jaffe's study dis-played consistent positive deviations from observed a. Deviationsranged from a low of -.001 to as high as +0.064 for the twenty-fivehydrous-silicates discussed.

Similarly, synthetic hydrous micas of this study display consistentlypositive deviations of fi,.u1o. from do6".. Only annites display a negativedeviation, and positive deviations as high as *0.087 are noted. Itwould thus appear that the value cited for k(HzO) by Larsen andBerman (1934) of 0.034 cannot, be applied directly to water in thesilicate minerals. A significantly smaller value for /c(IIrO) is impliedby the above data. Another source of error in the calculated K forsilicates may result from erroneous ft values for transition metals.Ja,tre (1956) notes that lc(Fe,Og) varies from 0.290 in silicates to 0.404in oxides. It thus appears that k for transition metals may be loweredconsiderably in a silicate environment. However, /c values for copper,cobalt, nickel, etc. are known only for the oxide environment. Thismay, in part, explain the anomalously high values for d calculated. itseems that further refinement of /c values are needed before the rule ofGladstone and Dale may be effectively applied to silicate minerals.

Souncns or Ennon

Optical examination revealed that the majority of trioctahedralmicas synthesized represent g9* percent reaction from starting ma-terials, and are thus assumed to be of ideal composition. Howevet,rubidium and cesium phlogopites represented only =2A-25 percent ofthe reactants in those runs. These micas are thought to approximateideal composition on the basis of the observed trioctahedral X-raypatterns and the predicted unit cell parameters. Due to difficulties instandardizing gallium in nitrate solution, the gallium phlogopite gelmay be slightly difficient in Ga3*, explaining why a maximum reactionof only 95 percent was obtained. Another possible source of error inthe assumed compositions was revealed through Miissbauer studies ofiron-bearing phlogopites. Wones, Burns, and Carroll (1971) haveshown a minimum of 10 percent Fe3* in all annites, and from 5 to 15percent Fez* in ferriphlogopites. Thus, one might also expect multiplevalence states in Ni, Co, and Cu-bearing micas. Seifert and Schreyer(1971) have demonstrated the presence of Mg2* in tetrahedral coordi-nation in Mg-rich synthetic trioctahedral micas. However, the assump-tion is made that all .R'9*-cations in this study are in octahedral coordi-nation unless noted otherwise.

In the investigation by Frondel and Ito (1966), and in this study,

113

tt4 HAZEN AND WONES

end-member zinc phlogopite KZnaAlSi3Olo(OH)z was not achieved.In all experiments in which mica ruas produced, 225 percent willemite-ZnzSiOn with minor leucite andfor glass were also present. While themica is clearly zinc-bearing, having cell parameters and indices of re-fraction higher than phlogopite, the excess willemite is evidence of lessthan three Znz* aloms per mica formula unit. Neumann (1949) hasdocumented the great preference of zinc for tetrahedral coordination.Thus, one possible explanation for such a zinc-poor mica is that thezinc enters the tetrahedral layer, while aluminum f.lls the three octa-hedral sites; f.e., KLlss'(Znz2*, Si2a*)3O1e(OH)r. A structural study ofthe natural zinc mica hendricksite from Franklin, New Jersey, wouldaid in an understanding of zinc's role in the layer silicates.

Synthesis of end-member manganese phlogopite-KMnaAISisOro(OH)r was also unsuccessful. Frondel and Ito (1966) report thattephroite-MnzSio+ is present as a major phase in all mica-bearingruns, while in the present study pyrochroite-Mn(OH)2 accompaniesthe mica phase. Thus, while the unit cell parameters of the mica aregreater than those of phlogopite, there are fewer than three manganeseatoms per mica formula unit. Burns (1970, p.43) has demonstratedfrom absorption spectra evidence that the distorted octahedral site ofthe phlogopite structure may stabilize manganese in the plus-threevalence state. Furthermore, natural manganophyllites invariably con-tain aluminum in more than 10 percent of the octahedral sites. There-fore, the manganese-poor mica synthesized in this study may representa solid solution between the components KMn32-AlSiBO10(OH)g *KMnz'.AlSiBOlo(OH)2 + KAlrAlSieOro(OH)2. Further study on nat-ural manganophyllites is needed to define the extent of Mn3*/Mn2*substitution in the mica's distoried octahedral sites.

Rnr,erroNs BETwEEN Cpr,r, PenauEf,ERS AND Iorvrc Renrr

There exist several systematic relations between unit cell parametersand ionic radii of substituting cations. For example, the cell dimensionsil*, b^, and c^ are each proportional to the Shannon and Prewitt (re-vised 1970) ionic radii of cations substituting into the tetrahedral,octahedral or interlayer positions. This relation is clearly demonstratedby Figure 1of. b^ vs. octahedral cation radii. The single exception tothis rule is that of c- vs. interlayer six-coordinated cation radii (Fig.2). The distinct negative curvature has been explained by Prewitt(personal communieation) as the result of increasing effective coordi-nation number of the interlayer cation with increasing ionic radius ofthis eation. For a given eation, an increase in eoordination number isaccompanied by an increase in effective ionic radius. Assuming the

SUBSTITUTIONS IN MICAS

bm in A"

Frc. l. Monoclinic b- unit cell dimension vs. ionic radius of the octahedral

E'9* cation for micas of the form K8"'* AlSLOro(OH)r. Black dots represent bio-

tites on the join phlogopite-annite synthesized by Wones (1963b).

relation C* vs. effective interlayer cation radius is linear, then therelation C* vs. six-coordinated cation radius should demonstrate theobserved negative curvature. As expected, unit cell volumes are lin-early related to the cube of the substituting cations' radii for octahe-dral and tetrahedral substitutions, and display a slight negative curYa-ture in the interlayer case (Figs. 3 and 4).

It is of interest to consider how b. (the cell dimension within themica layers) varies with respect to d661 (the dimension perpendicularto the layers) for each type of cation substitution. A plot of'b- vs'

.sN+E

o

E

Izo

b, o lon ic Rodius R+2

116 HAZEN AND WONES

Frc. 2. Monoclinic c^ unit cell dimension vs. ionic radius of the interlayer .R*cation for micas of the forrn ,E.Mg"AISLO* (OH),.

door (Fig. 5) demonstrates that octahedral, tetrahedral, and interlayercation substitutions have differing effects on the size and shape of theunit cell. For example, octahedral substitutions have a profound in-fluence on bm, while d661 remains virtually constant. The near-verticalslope of Lhe R2. line is a result of this fact. It should be noted thatthese observations agree with the theoretical predictions of rakedaand Morimoto (1970). On the other hand, interlayer cation substitu-tions alter the thickness, door, of the layers, while having a muchsmaller effect on b*. R"* and .En' tetrahedral substitutions influenceboth b- and dee1.

SuesrrrurroNs AND Srerrr,rry

Interlayer and tetrahedral cation substitutions demonstrate that awide range of ionic radii are possible in these positions. Interlayer

Qr .eo

z

zo

o1 .20

Lrl

JEUFz

C Eugstor a Munoz 0966)

O Co rmon , J .H . ( 1969 ,

O This srudy

C m i n A

SUBSTITUTIONS IN MICAS LI7

cations vary from sod.ium (ionic radius = 0.98 A) to cesium (1'70)'

Tetrahedral cations from boron (0.12) to trivalent iron (0.49) form

stable micas. However, octahedral cations seem far more restricted

in their ability to substitute into the phlogopite structure' No 'R2*

cation of radius greater than ferrous iron (0.78), including lead (1.18)

cadmium (0.9.5) and manganese (0.83) , was found to form a stable

mica. Furthermore, Eugster and wones (1962) have demonstrated that

the Fe2* mica, annite, is far less st'able than phlogopite. Thus, it ap-

pears that the stability of trioctahedral micas may be in part' a func-

tion of the octahedral cation's radius.It is well known that in phlogopite the ideal AISis tetrahedral layer

is larger than the Mgs layer (Radoslovich and Norrish, 1962) ' If the

trioctahedral mica is to be stable, then these two layers must coincide,

either by expansion of the octahedral layer in the plane of a* and b^

or by contraction of the tetrahedral layer within this plane. Radoslo-

vich and Norrish suggest four ways to accomplish this:

&

olrJ@D(,

qlE

=oE

C'2o

4 9 0

rr uNlr cEtt- vot-ume (A!)

Frc. 3. Monoclinic unit cell volume vs. the aube of the octahedral Rs* cationradius for micas of the form KE"'*AISLOt(OH),.

5K)

OCTAHEDRAL CATION SUBSTITUTIONS

K RtzAtSisoro (OH)2

. IYONES (1963 )

l 18 HAZEN AND WONES

Is

ft

olrJ@f(J

=oTE

ozo

o-O.9

olrJo39o.eIE

o(r o.3()zI

Fc*lTETRAHEDRAL CATION

Go.!ASUBSTITUTIONS

KMs3 f3Si3oto(OH )2

Al+3

B+3{tO .r05 gOO OOSIM UNIT GELL volumE (45)

Fro. 4. Monoclinic unit cell volume vs. the cube of the interlayer R* cationradius for micas of the form ,R*Mg"AlSLOrc(OE;n, *4 vs. the cube of thetetrahedral .Re' cation radius for micas of the form KMgs-Rr*SLOro(OH)r.

INTERLAYER CATION SUBSTITUTIO

R+Mgs AtSisOrc (OH12

Q eugrrer A Munoz (t9O6)

Q Cormon. J . H . ( t969)

Q rt ir sruay

SUBSTITUTIONS IN MICAS

1) altering bond lengths of the ideal layers,2) tetrahedral layer tilting or corrugation,3) octahedral layer flattening, or4) tetrahedral layer rotation.

The altering of bond lengths is energetically far more difficult than

altering bond angles. Thus, while such distortions have been noted in

pure fluorpolylithionite KAILi2Si4OroFz (Takeda and Burnham, 1969),

bond stretching or contraction is assumed to be a minor effect in Alsia

or Fe3*Sis tetrahedra. Tetrahedral tilting or corrugation is also well

documented by Takeda and Burnham in their mica with partially

ordered Alliz octahedral layer. However, they believe that tilting of

tetrahedra will be minimized when all octahedral positions are filled

by the same cation.Donnay, Donnay, and T'akeda (1964) have demonstrated that the

d o o r = C t n . s i n p n l ( A )

Frc. 5. Monoclinic interlayer spacing d- vs. monoclinic b* unit cell dimension.

The four lines represent micas of the forms -B*Mg"AlSi*oto(oH)r, KB"',*AlSi,o'n-

( OH),, KMg"R$Si" (OH) ",

and KM g"Alft #*O'.(OH),.

119

E

E!

R*2'R+4

Fo+2

, l R + 3

tto

A . Won.t (1963)

Q Eugsrc. I Munoz (1966)

Q Cormon (1969

120 HAZEN AND WONES

octahedral layer may conform to the larger tetrahedral layer byoctahedral layer flattening (see Fig. 6). rn this way bond rengths arepreserved while bond angles are altered. The amount of compressionmay be represented by the angle g, which has the value E4o4{ in anideal octahedron. If the assumptions are made that:

1) there is no tetrahedral tilting or corrugation (i.e., basal oxygensin each tetrahedral sheet are coplanar),

2) (001) projections of tetrahedra are equilateral triangles, and3) a* - b i lG)v" ,

then g is a simple function of the mean octahedral bond length d,o andcell dimension b*: sin r2 = b*/3(3)%'do. The mean octahedral bondlength for Mg-(O, OH) and Fe,*-(O, OH) and tr'e2*-(O, OH) aregiven by Donnay, Donnay, and Takeda (19G4) as 2.07 A and 2.12 Lrespectively. Mean bond lengths for other octahedral cations may becalculated by interpolation or by adding cation radius to that of

OCTAHEDRAL LAYER COMPRESSION

V = Arc sin (b'/36.do )

h . 3 .AB

do r ltlO

oo lProirctiont

ldeol Oclohedron:V =S4o44'

F lo t tened

Y t , '11 ,''-11.,'M'....

Frc. 6. Expansion of the octahedral 001 projection by octahedral layer compres-slon.

Y Arlr

Prolaciioot

.t > 54?44

SUBSTITATIOITS IN MICAS

oxygen (1.38 A) . Thus, knowing b*, we can calculate g, for eachoctahedral layer substitution. In Figure 7, g is plotted vs. octahedralcation radius. As ionic radius increases, the value of ,7 is noted to de-crease slightly. Thus, larger octahedral cations require less site flatten-ing to conform to the AlSig tetrahedral layer. While octahedral layerflattening is a real effect in hydrous trioctahedral micas, this structuralparameter does not explain the instability of 100 percent octahedralsubstitutions of cations larger than Fez*.

tzl

o.78Fe*2

a

a

r Woneg (1963)

o.74

60"

V = A, rc s in ( [ 'n /3 , /T .do l

Tlc. 7. Octahedral layer compression angle 'y' vs. ionic radius of the octahedralrB'* cation in micas of the form K.Eg'z*AISLOD(OH),' Black dots represent biotiteson the join phlogopite-annite synthesized by Wones (1963),

o

.=AI+(E

oIE

9zo

o.70

722 HAZEN AND WONES

Tetrahedral layer rotation is a fourth means of fitting the non-equivalent octahedral and tetrahedral layers (see Fig. 8). Donnay,Donnay, and Takeda (1964) have shown that by rotating each tetra-hedron through an angle o about an axis perpendicular to the (001)plane, the effective size of the tetrahedral sheet is reduced. Structurestudies by Steinfink (1962) and others reveal values for c may begreater than 10o in natural micas. Thus, in phlogopite the strain be-tween octahedral and tetrahedral layers may be released primarilythrough tetrahedral layer rotation.

If the conditions assumed by Donnay, Donnay, and Takeda (1964)for octahedral Iayer flattening are correct, then o is defined by themean tetrahedral bond length d; and the cell dimension b*: cos o =b^/4'(2)v,.dt. The mean tetrahedral bond length for the AlSi3 layeris known to be 1.643 :t .002 A from studies of muscovite (Giiven, 1967and Burnham and Radoslovich, 1964), biotite (Franzini, 1963), andfluorphlogopite (McCauley, 1968). With this value of d1, and the

TETRAHEDRAL LAYER ROTATION OI

o : Arc cos l t ^ /4 , /T .d r l

Frc.8. Contraction of the tetrahedral 001 projection by tetrahedral layer rotation.

I Fe*zIa

a

SUBSTITUTIONS IN MICAS

o.7

{ o.z

or = Arc cos(b. /4€ 'd1)Frc. 9. Tetrahedral layer rotation angle a vs. ionic radius of the octahedral .Rn'

cation for micas of the forn K.EJ-AISLO-(OH)g. Black doLs represent biotiteson the join phlogopite-annite synthesized by Wones (1963b).

known values oL b*, a plot of R2* ionic radius vs. a has been con-

structed for micas of the form KRa'*AlSisOlo(OH)2 (see Fig.9). Asthe octahedral cation radius increases to 0.76 A, a approaches thecritical value of 0o. For octahdral cations of ionic radius greater than=0.76 A, the tetrahedral layer cannot expand further by rotation. Itmight therefore be expected that hydrous trioctahedral micas with anAlSig tetrahedral layer would not be stable for an octahedral layercation'of radius greater than about 0.76 A.

t23

.sN+E

ct

E

( J n

= - 'o

I?L HAZEN AND WONES

Ocresnonel Cerrox DrsrnrsurroN rx Neruner, Mrcls

Foster (1960) has plotted the octahedral cation content for over 200natural phlogopites, biotites, and siderophyllites (Fie. 10). As the Fe2.content of these micas increases, so does the octahedral aluminumcontent. Trivalent aluminum in -82* sites requires a corresponding sub-stitution of aluminum for silicon in the tetrahedral layer. Thus, alu-minum has the dual effect of increasing the size of the tetrahedrallayer, while decreasing the effective octahedral cation radius. Themaximum observed effective octahedral ionic radius, for the mostiron-rich, aluminum-poor specimens, is 0.74 A. Similarly, mangano-phyllites are known with almost 20 percent MnO substituting for MgO(Jakob, L925), resulting in an effective octahedral ionic radius of 0.74A. Thus, while octahedral cations in natural micas of the form K-8,.AlSiBOlo(OH)s approach the critical ionic radius of 0.76 A, they arenot observed to exceed this value.

EXPLANA- I ION

Phtogopitc5

M8 biolitct

Mc- tc { r b io i i t6 !

S i ( l c rn fby l l i l es . i , J

F o s t e r , 1 9 5 0

F c i z { + m r r )

Fto, 10. The composition of the octahedral layer of more than 200 natural phlogo-pites, biotites, siderophyllites, and lepidomelanes from Foster (1960).

ST] BSTITA TIONS /.If MIC AS

Tun CouposrrroN or Axxrrn

synthetic annite was noted to be the only hydrous trioctahedralmica of the form KEs'.AlSi3Oto (OH), which appears to have an aver-age octahedral ionic radius greater than the critical value of 0'76 A.Eugster and Wones (1962) have demonstrated that trivalent iron(octahedral ionic radius : 0.63 A) may substitute for octahedral diva-lent iron (0.78 A) in annite as expressed by the oxyannite reaction:

KFes' *A1Si.O ro (OH), e K(Fe' *Fe,t *)Alsiro,, * Hr.

An annite with =12 mole percent octahedral Feg* ('i,.e., =18 mole per-

cent oxyannite) has an average octahedral cation radius of 0.76 A,and it was thus predicted that even the most reduced synthetic annitesmay have appreciable oxyannite content. Subsequent study by Wones,Burns, and Carroll (1971) employing Mijssbauer and analytical chem-istry techniques have confirmed that at least 10 mole percent of octa-hedral iron in all synthetic annites is in the trivalent state. It thereforeappears that octahedral cation size restrictions, resulting from the

misfit between octahed.ral and tetrahedral mica layers, ffi&Y have aprofound effect on the valency of iron in annite.

From Figure 9 it can be seen that for synthetic biotites of high iron

content, tetrahedral rotation (i.e., ")

is zero. Therefore, from Donnay,Donnay, and Takeda (1963):

cos d : | : b^/4.(2)"" d,

for these micas. However, Wones (1963b) has shown that values for

b* increase with increasing Fe content, in these high-iron biotites. It

must therefore be assumed that dr is also increasing in order to main-

tain the relation b,o/ifi = 4(2)'/' for these micas' One possible way to

increase the mean tetrahedral bond length d, is by substitution of Fes*

for Al'* in the tetrahedral layer. Since b* fot annite : 9.348 A, then

dt = 9.348/4(2)v" = 1.652 A. Donnay, Donnay, and Takeda (1964)

have suggested a value of 1.68 A for dr of the Fesi3 tetrahedral layer,

as opposed to the smaller 1.643 a mean tetrahedral bond length for an

AlSig sheet. Therefore, dt = 1.652 implies a cornposition of (Fes'23*,

Ale.s3-)Si3 (i.e., =7 percent total iron is trivalent and in tetrahedralsites) for annites' tetrahedral layer. Indeed, Miissbauer studies by

Burns (see'Wones, Burns, and Carroll, 1971) confirm that 6'5 percent

total Fe is tetrahedral Fe8*!

Pnmrcrrom oF TRrocrAuponer, Mrce Sresrurrv

It has been shown lhat b* is proportional to the octahedral cationradius (Fig. 1). But we know that cos c is proportional to b*/ilt.

126 HAZEN AND WONES

Therefore, cos c is propodional to octahedral ionic radius/d6. Thislinear relation is demonstrated in Figure 11, a plot of cos o vs. -R2*ionic radii for varying mean tetrahedral bond length d;. The line foran AlSi3 tetrahedral layer (d5: 1.643) has been developed previously(Fig. 9). Donnay, Donnay, and Takeda (1964) suggest a value of di= 1.68 A for the FeSi3 tetrahedral layer, and this value has been usedio obtain a second line on Figure 11 defined by Nir-, Mgzt, Coz*, andFe2* ferri-phlogopites. By noting that these two lines are parallel, and.by calculating additional mean tetrahedral bond lengths from data of

+(r

ot

ozo

b^ /4 ' /2.d, (= cos o)

Frc. 11. Cosine of the tetrahedral layer rotation angle a vs. octahedralcation radius for micas of the form Kn,b(AISis)O,o(OH)* [dt = I.MB]K.&"'t(FeSL)Oro(OH)o [dr : 1.68.]

n",and

. won.r (1963)

(Fe+.Sir)

d r

TETRAHEDRA= 1 .68 Co+2 0

(Arsir) TETRAHEDRA

d r = 1 . 6 4 3

^ o 3 0

E

a

o - -

Meon Tetrohedrol -Bond Length .

d 1 i n A

t 7 8 1 7 0t 7 4 t . 72

o 9 4n ..4

Frc. 12. A nomogram for cos a vs. octehedral -82* cation radius vs. mean tetrahed-ra,l bond length for aII hydrous, potassic, trioctahedral micas'

Shannon and Prewitt (rev. 1970), additional lines can be drawn for

the BSis, GaSi3, and AlGe3 tetrahedral layers. The resulting nomogram

is found in Figure 12. The intersection of any line with cos o = 1.00

defines the critical octahedral cation radius for a hydrous trioctahedral

mica with a mean tetrahedral bond length corresponding to that line.

Thus, if the composition of a hydrous trioctahedral mica is known,

systematic relations between composition and ionic radii enable us to

predict unit cell dimensions, structural parameters' and even the

stability of the mica.

Acxwowr,pocuoNrs

The authors wish to express their deep appreciation to Dr' Charles W. Burn-ham and Dr. Iliroshi Takeda for their careful reviews of this study. Their manycomments and suggestions have greatly improved the quality of this work' Manythanks are also due to Dr. Ja.mes Munoz and Dr. Charles T. Prewitt for theirstimulating discussions and helpful advice.

Messrs. Robert Charles, Joseph Chernovsky, Yves Pelletier, and Dr. David

SU BSTITU TIONS 1A/ MIC AE

0.96 0 9s

b ^ / 4 ' E d r 1 = c o s o )

r27

too

128 IIAZEN AND WONES

Hewitt aided in many aspects of laboratory techniques and maintenance. Manyhours of labor were saved through their suggestions and aid. Finally, we wish tothank Mrs. Betsy McCrory for her careful help in preparation of the manuscript.

This investigation was supported by National Science Foundation grantsGA1109 and GA13092 to Dr. David R. Wones.

Rerpnuwcus

BunNrrenr, C. W., eNl E. W'. Reoosr,ovrcn (1964) Crystal structures of coexistingmuscovite and paragonite. Carnegie Inst. Wash. Yearbook 63, 232-236.

BunNs, R. G. (1970) Mineralogical Applications ol Crgstal Field Tlteorg. Cam-bridge University Press, Cambridge, England, 224 p.

Cenuex, J. H. (1969) The Studa oJ the System NaAlSiO+-MgnSiOt-SiO,-H"Ofrom 200 to 6000 bars and, 800'C to ilA1"C and lts Petralogic A'yplicati,ons.Ph.D. Thesis, Penn. State Univ.290 p.

Cnowr,rv, M. S., eNo R. Rov (1960) The effect of formation pressure on sheetstructures-a possible case of AI-Si ordering. Geochi,m. Cosmoch'im: Acta 18,94-100.

DpVnrrs R. C., eNr R. Roy (1958) The influence of ionic zubstitution on thestability of micas and chlorites. Econ, Geo1.53,958-965.

DoNrrrev, G., J. D. H. DoNNay, ewr H. Ternre (19&t) Trioctahedral one-layermicas. II. Prediction of the structure from composition and cell dimensions.Acta Crystallogr. t7, 137l-1381.

EnrsoN, T. A. (1916) Precipitation of nickel and cobalt hydroxide. U.S. Pat.#1,1€1,484. [Chem. Abstr. ro,725 (1916)].

Eucsrnn, H. P. (1957) Heterogeneous reactions involving oxidation and reduc-tion at high pressures and temperaturx. J. Chem. Phys.26,7160.

-, ewn J. Muwoz (1966) Ammonium micas: Possible sources of atmosphericammonia and nitrogen. Sci,ence 151, 683-686.

aNo D. R. Wowns (1962) Stability relations of the ferruginous biotite,annite. J. Petrologg 3, 82:-725.

exn T. L. Wnrcnt (f96.0) Synthetic hydrous boron micas. U.S. GeoI. Suru.Pro l. P ap. 4oO, B.44l-B'442.

EveNs, H. T., Jn., D. E. Appr,nuAN, AND D. S. HaNnwnnr<nn (1963) The lastsquares refinement o{ crystal unit cells with powder diffraction data by anatrtomatic computer indexing method (absft) Amer. Crgst'al,lngr. Assoc.,Cambridge, Mass., Ann. Meet., Progra;m. p.4243.

Fosrnn, M. D. (1960) Interpretation of the composition of Trioctahedral micas.U.S. Geol. Suru. Prol. Pap.354-8, 1146.

FneNzrNr, M. (1963) On the crystal structure of biotite. Z. Kristallngr. 1t9,297-309.

Fnowonr,, C., ewo J. Iro (1966) Ilendricksite, a new species of mica. Am,er. Min-eral 5r,1107-lr2B.

Gr,eosrowu, J. H., axn T. P. Der,o (1864) Researches on the refraction, dispersion,and sensitiveness of liquids. Phil. Trans. Roy. Soc. Lonclon 153, 337-348.

G0vnw, N. (1967) The crystal structure of 2Mr phengite and 2Mr muscovite.C ame gic Inst. W osh Y earb o oh. 66, 487 492.

Ilatcn, R. A., R. A. Hurrprrnny, W. Errrr,, aNo J. E. Counr,ono (1957) Syntheticmica investigations. IX. Review of progress from lg47-1955. U. S. Bur. Mines,Rep. Inu. 5337.

Jarru, I{. W. (1956) Application of the rule of Gladstone and Dale to minerals.Amer. Mineral. 41,757-777 .

SUBSTITI]TIONS IN MICAS I29

Jeroa, J. (1925) Beitrage zur chemischen konstitution der glimmer' I' Mit-

teilung: die schwedischen manganophylle. Z. Kri'stalbgr. 61' 155'

Kr,rr.rcsnnnc, C., axo R. Rov (195?) Synthesis, stability and polytypism <if nickel

and gallium phlogopite. Amer. Mineral 42,629-634.Lensuw, E. S., aNn H. BnnuaN (1934) The microscopic determination of the

nonopaque minerals. U.8. GeoI. Swu. Bu'11.848' 266 p.

McCeur,nv, J. W. (1968) Crystal Stnrctures of tlte Mioas KMg'AISi'OnFt ond

BaLiMgeALSisO'Fr. Ph.D. Thesis, Penn. State Univ', 180 p.

NnuuenN, E. (1949) Notes on the mineralogy and geochemistry of zinc. Mineral.

Mag. 28,575-581.Raoosr,ovrcr, E. W., arvo K. Nonnrsn (1962) The cell dimensions and symmetry

of layer lattice silicates. L Some structural considerations. Amer. Mi,neral.

47,599-616.Scnernrn, J. F., ello N. L. BowoN (1955) The system K,O-AlrO"-SiOr. Amer' J'

sci. 253,681-746.Snrrunr, F., eNo W. Scnnpvnn (19?1) Synthesis and siability of micas in the sys-

tem K2O-MgO-SiO,-H,O and their relation to phlogopite. Contri'b' Min-

eral. Petrologg 30, 196-215.SneNNoN, R. D., aNo C. T. Pnowrm (1970) Revised values of efiective ionic

ndli. Acta C rgstallogr. 26, 1046-1048.Suew, I[. (1963) The four-phase curve sanidine-quartz-liquid-gas between 500

and 4000 bars. Amer. Mineral.48, 883-896.Surru, J. V., enn II. S. Yonrn (1965) Experimental and theoretical studies of the

mica polymorphs. M ineral. M ag. 31, 205-235.StnrwFtNr, H. (1962) Crystal structure of a trioctahedral mica: pliogopil"e' Amer'

Mineral.47, 886-896.SrusrcoN, V.. awn R. Rov (1962) Boron substitution in synthetic micas and clays.

Amer. M'iner aI. 47, 1166-1173.Tarnoe, II., aNo C. W. BunNueIvr (1969) Fluor-polylithionite: A lithium mica

with nea,rly hexagonal (SirOE)' ing. MineraL J. 6, 102-109.awo N. Motruoro (1970) Crystal chemistry of rock-forming silicates' II'

Structural changes in solid solutions. J. Crgstallogr- Soc. Jap. tz,23l-248, lin

JapaneseJ.Tunrr,n, o. F. (1949) Two pressure vessels for silicate-water studies. GeoI- Soc.

A'mer. BuIl. 60, 1727-1729.Wrsp, W. S., eNo H. P. Eucstpn (1964) Celadonite: Synthesis, thermal stability

andoccurrence. Amer. M'ineral. 49, 1031-1083.WoNns, D. R. (1963a) Phase equilibria of "ferriannite," KFe"*'Fe$SLO-(OH),

Amer. J. Sci. 26t, 581-596.- (1963b) Physical properties of synthetic biotites on the join phlogopite-

annihe. Amer. M iner aI. 48, 1300-1321.- (1967) A low pressure investigation of the stability of phlogopite. Geo-

ch.i,m. C osmochi'm. Acta 31, 224&-2253.R. BunNs, eNo B. Cannor,r, (1971) Stability and properties of annite.

( abs.) ?raas. Am er. G eophg s. U ninn 52, 369-37 0.ello I[. P. Eucsrpn (1965) Stability of biotite: Experiment, theory and

application. Amer. M'ineral. 50, 122Vt272.Yoonn, H. S., alro H. P. Eucsrnn (1954) Phlogopite svnthesis and stability range'

Geochi,m. C osmoch,i'm. Acta 6, 157-185.

Maruncript receiued, Mag 10, 1971; accepted Jor publication, Ju;ne 22, 1971'