2006 - New Data on Sepiolite and Attapulgite

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NEW DATA ON SEPIOLITE AND ATTAPULGITE 1

By

F R E D A . MU M P T O N A ND R U S T U M R o Y

The Pe nnsylvan ia Sta te Univers ity , U nivers ity Par k, Pen nsylvan ia

A B S T R A C T

Hyd ro the rmal s tud ies have fa i led to y ie ld syn the t ic a t tapu lg i te o r sep io l i te s in the sys -tem M gO-AI~O3-SiOr-H~O. However, the n atur al m inerals can be decomposed to yie ld mont-

mori l lono ids by mild hydro the rm al t rea tment a s low as 200 ~C and p robab ly as low as 100 ~C.These da ta ind ica te tha t they a re m etas tab le and p robab ly cou ld no t have fo rmed a t thesetempera tu res .

Dry dehyd ration a t 400 ~ and 750~ gave no evidence for the presence of "zeoli t ic wa ter"in these minera ls and fa i led to es tab l ish the ex is tence o f "anhydr id e" phases. The f ie lds tudy of re la tion ships in one sep ioli te local i ty suggests th e im portan ce of s tructu ral con trolin the formation of these minerals .

I N T R O D U C T I O N

R e c e n t l y s ev e r a l w o r k e r s h a v e i n v e s t i g a t e d v a r i o u s s u b s y s t e m s a n d j o i n s

w i t h i n th e s y st e m M g O - A 1 2 0 3 - S i O 2 - H 2 0 a t e le v a te d t e m p e r a t u r e s a n d p r es -

s u r e s ( Y o d e r , 1 9 5 2 ; R o y a n d R o y , 19 5 5 ; M u m p t o n a n d R o y , 1 9 5 6 ) . A l t h o u g ht h e s t a b i l i t y r e g i o n s f o r m o s t o f th e n a t u r a l m i n e r a l s t h a t f a ll in t h i s s y s te m h a v e

b e e n d e t e r m i n e d , t h e r e s t i l l r e m a i n s e v e r a l m i n e r a l s t h a t h a v e n o t b e e n s y n t h e-

s i ze d , 2 o r t h a t c a n n o t b e a s s i g n e d d e f i n i t e s t a b i l i t y l i m i t s . O w i n g t o t h e d i f f i -

c u l ty o r i n m a n y c a s es t o t h e i n a b i l i t y , o f s y n t h e s i z in g s u c h m i n e r a l s a s n a e r i t e ,

d i c k i t e , a n t h o p h y l l i t e , a t t a p u l g i t e , 3 a n d s e p io l i te , q u e s t i o n s r e g a r d i n g t h e o r i g i n

- - w h e t h e r s ta b l e o r m e t a s t a b l e - - o f t he s e m i n e r a l s a r e o f te n r a i s e d a n d l ef t u n -

a n s w e r e d .

T h i s p a p e r p r e s e n t s n ew d a t a a c c u m u l a t e d o n t h e a t t e m p t e d s y n t h e se s , t h e

s t a b i l i t y r e l a t io n s , a n d t h e r e a c t i o n s o f a t t a p u l g i t e a n d s e p i o li t e u n d e r b o t h d r y

a n d h y d r o t h e r m a l co n d i t i o n s . F r o m t h e s e d a t a s u g g e st i o n s r e g a r d i n g t h e o r i -

g i n o f th e s e p h a s e s c a n b e c o r r e l a t e d w i t h t h o s e in t h e l i t e r a t u r e a n d w i t h f i e l d

o b s e r v a t i o n s .

A t t a p u l g i t e a n d s e p i o l i t e a r e f i b r o u s c l a y m i n e r a l s e a s i ly c o n f u s e d w i th e a c h

o t h e r i n h a n d s p e c i m e n . F r e q u e n t l y f i e l d s p e c i m e n s o f t h e se m i n e r a l s a r e d e -

s c r i b e d a s m o u n t a i n l e a t h e r , m o u n t a i n c o r k , a n d m o u n t a i n w o o l , i n o b v i o u s

r e f e r e n c e t o t h e i r e x t e r n a l a p p e a r a n c e . H o w e v e r , s e p i o li t e a n d a t t a p u l g i t e m a y

r e a d i l y b e d i s t i n g u i s h e d f r o m e a c h o t h e r a s w e ll a s f r o m o t h e r c l a y m i n e r a l s b y

1 C ontribution no. 56-44, College of Minera l Industries , The P ennsylv ania Sta te U nivers ity ,

Univers ity Park, Pa.z Altho ugh Bow en and T uttle (1949 ) c la ime d to have synthesized sepioli te , Professor Tut-t ie informs us that the evidence was scarcely suffic ient for posit ive identif ic ation of thisphase.3 T he nam e pa lygorsk i te i s e s sen t ia l ly synonymous wi th a t tapu lg i te , and m ay have p rece -dence.

1 3 6



FRED A. MUMPTON AND RUSTUM ROY 137

powder x-ray diffra ction patterns (Longc hambo n, 1937; Bradley, 1940). The

general str ucture of attapulgite is well established (Bradley, 1940) ; it consists

of a two- dimensi onal layer s tructure more closely related to the chainli ke struc-

tures of the amphiboles than are other clay minerals. The structure of sepiolite

has been suggested by Migeon (1936), Longchambon (1937), and Nagy and

Bradley (1955) , to be simila r to that of attapulgite.

TABLE 1. - ANALYSES OF SEPIOLITES AND ATTAPULGITES

1 2 3 4 5 5 7 8 9 10 11

SiO2 54.83 49.30 52.50 55.34 55.25 51.17 46.67 53.96 54.71 54.04 55.03

A1203 0.28 1.95 0.60 1.81 9.67 13.73 9.84 8. 56 13.48 9.83 10.24Fe~O3 0.45 2.99 0.43 2.32 1.55 0.93 3.10 2.10 3.52 3.53FeO - - 0.70 - 0.19 0.31 1.22 0.19 - 0.19 -MgO 24.51 18.20 21.31 22.95 8 .92 6.40 8.94 10.07 5.44 9.07 10.49CaO 0.55 5. 15 0. 47 0. 24 1.65 2.89 8.36 2.01 2.79 1.69 -K~O 0.03 - - - 0.10 - - 0.03 - 0.08 0.47Na_~O 0.35 - - - 0.76 - - 0.39 - 0.57 -

H~O- 8.18 20.50 21.27 8. 60 9.48 10.29 8.29 9. 79 8. 65 10. 00 9.73H.~O+ 10.74 10.20 10.03 13.24 15.84 11.51 12.63 10.93 10.13CO2 - 4.10 . . . . . . . . .T i O ~ . . . . 0.44 - - 0.24 - 0.32 -Total 99.92 99.20 99.84 99.57 99.81 99.58 100.09 99.85 99.80 100.24 99.62

1. Sepiolite, Yavapai County, Arizona (Kauffman, 1943).2. Sepiolite, Salinelles (Gard), France (Migeon, 1936).3. Sepiolite, Ampandandrava, Madagascar (Caill6re, 1951).4. Sepiolite, Durango, New Mexico (Shannon, 1929).5. Attapulgite, Quincy, Florida (Kerr and others, 1949).6. Palygorskite, Nizhni Novgorod, U.S.S.R. (Cai116re, 1936).7. Palygorskite, Siberia, U.S.S.R. (Caill~re, 1936).8. Attapulgite, Attapulgus, Georgia (Kerr and others, 1949).9. Palygorskite, Taodeni, Sahara, Algeria (Caill~re, 1936).

10. Attapulgite, Attapulgus, Georgia (Kerr and others, 1949).11. Attapulgite, Attapulgus, Georgia (Bradley, 1940).

Several chemical analyses from the literature are listed in Table 1 and are

included to show two impor tant points. First, it is apparent fr om these analy-

ses that sepiolites are hydr ous ma gne siu m silicates which cont ain small amount s

of alumina, while attapulgites contain substantial quantities of a lumina. In

nature there does not seem to be any evidence for a continuous solid solution

series between the two, although this might be expected from the postulated sim-

ilarit y of their structures. One cannot, however, arrive at any final conclusions

from analyses of the mount ai n leather miner als because of (1) the relative

paucity of analyses, and (2) the difficulty involved in obt ain ing pure samplesfree from admixed quartz, calcite, and other clay minerals. The second, and

more impor tant point to be made from the analyses is the fact that CaO is always

reported in attapulgites and sepiolites. While this may be due to the freque ntly

present lime-containing impurities such as calcite, montmorillonite , or amphi-



138 N E w DATA ON SEPIOLITE AND ATTAPULGITE

bo les , i t is more t han poss ib l e t ha t CaO i s an es sen t ia l cons t i t uen t o f t hese min -

era l s themselves .

N A T U R A L O C C U R RE N C ES

S ep io l it e and a t t apu lg i t e occu r i n so i ls , s ed im en ta ry " c l ay dep os i t s ," and a l-

t e r a t io n p r o d u c t s o f c e rt a i n b a s ic i g n e o u s r oc k s , a n d t h e y a r e n o t u n c o m m o n

a s m i n o r c o n s t it u e n ts o f m a n y s e d i m e n t a r y r o ck s . T h e l it e r a tu r e , h o w e v e r , p r e -

sen ts an am biguou s p i c tu re o f t he genes is o f t hese minera l s . The i r p resence i s

o f t en repo r t ed , bu t d e t a i l ed desc r ip t i ons o f t he i r r e l a t i on t o ac com pan y ing min -

e ra l s a re f r equen t ly mi s s ing . Al tho ugh bo th minera l s a re foun d in s imi l a r en-

v i ronm en t s , t he p resence o f bo th i n t he s am e depos i t i s no t comm on .La ppa ren t (1936) s t a te s t ha t s ep io li te i s fo rm ed by t he ac t i on o f ma gnes ium -

r i ch S o lu ti ons upon s i li ceous gels i n t he p resence o f l ime . Lo ngc ham bon

(1935) a t t r i bu t es t he o r ig in o f pa lygorsk i t e to t he a l t e ra t i on o f py roxenes an d

amp hibo l es , wh i le K er r (1937) sugges t s t ha t t he a t t apu lg i t e f rom Geo rg i a was

fo rm ed by the a l t e ra t i on o f mo n tm or i l l on i t e minera l s . Ca ill~ re and H 6n in

(1949) have sa id t ha t ce r t a in s ep io li te s a re s econd ary p roduc t s r e su l t i ng f rom

the we a the r ing o f enc los ing se rpen t ine bod i es . S ep io li te , r e sembl ing meta -

co l l o ida l a sbes tos , has been repo r t ed b y S e rdyuc hen ko (1949) t o occu r i n s ili-

c i f i ed s e rpen t in i t e s accom pan ied b y ve in le t s o f quar t z , opa l , an d ca l c i t e , rep l ac -

ing o lde r ca rb ona t e hos t rock . Geras imov , Grushko , and C h i rv insky (1949)s t a t e t ha t pa lygo rsk i t e has been foun d as a f i b ro us ve in m inera l i n ce l l u l a r l ime-

s tones and do lomi t es . Bo th f i b rous and l am el l a r s ep io li te were r epo r t ed f ro m

so lu t ion cav it ie s i n a M adag asca r l imes tone (LaC ro ix , 1940) . In a r ecen t paper ,

He ys t ek and S chm id t (1953) sugges t t ha t i n t he p rog res s ive we a the r ing o f abasa l t , i t a l t e rs f i r s t t o mon tmo r i l l on i t e and t he n t o a t t apu lg it e . The a m oun t

o f a t t apu lg i t e i n any one wea the r ing zone o f t h i s basa l t can be co r re l a t ed

r o u g h l y w i t h t h e q u a n t i t y o f c a r b o n a t e p r e se n t .

F ro m these r epo r ts a fu r the r q ues t i on ma y he ra i s ed : i f t he s ep io l it e and a t t a -

pu lg i t e g ra ins i n ce r t a in s ed imen t s a re no t de t r i t a l , why shou ld Mg 2~, SiO42-,

e t c. , have com bined to fo rm sep io l it e (o r a t t apu lg i t e ) r a the r t h an a mo n tmo r i l -

l on i t e o r t a l c? Th i s p rob l em i s accen tua t ed by t he i nab i l i t y t o syn thes i ze s ep io -

l i t e or a t tapulg i te .

E X P E R I M E N T A L

A l t h o u g h t h e a u t h o r s ( M u m p t o n a n d R o y , 1 95 6 ) p r e v i o u s ly e n c o u n te r e d

ne i t he r s ep io l it e no r a t t apu lg i t e in t he m on tm or i l lon i t e - sapon i t e po r t i on o f t he

sys t em MgO -AlzO3-S iOz- -H20 ( see F ig . 1 ) , syn the t i c gel m ix tu re s were spe-

c i f i ca l ly p repa red wi th the ap p rox im ate com pos i t i ons o f an average sep io l it ea n d a n a v e r a g e a t t a p u l g it e ( m i n u s C a O ) . T h e o x i d e r a t io s i n t h e se tw o a m o r -

phous s t a r t i ng ge ls a re :

A tta pu lgi te ge l, 69.0 SIO 2:9.2 A1_~O3:21.8 M gO

Se piol i te gel , 59.6 SIO2:2.3 AlzOa :38.1 M gO



FRED A. MUM PTON AND RUSTUM Ro Y

QUARTZ

13 9

T A L CORDIERITE

HYDRALSITE

S E R P E N T I N E

A M E S I T E

DLINOCHLORE

B R U C I T E S P I N E L D I A S P O R E

FIGURE ] . - Co mp atibility tetrahedro n for the sy stem MgO-AI~Oa--SiO~H~O (projected onthe anhydrous base) at 300~ and 1000 atm ., showing stable assemblage of phases. S and.4 represent th e com positions of the sep iolite and attapu lgite ge ls studied. Othe r solid dotsrepresent com positions studied earlier. The w hite circular areas are single-phase mon tmor-illonoid areas.

T h e s e g e l s w e r e h e a t e d u n d e r h i g h w a t e r p r e s s u r e i n " t e s t t u b e " p r e s s u r e v e s -

s e l s f o r p e r i o d s v a r y i n g f r o m e i g h t h o u r s t o t h r e e w e e k s . T h e d e t ai ls o f th e h y -

d r o t h e r m a l m e t h o d s a n d e q u i p m e n t h a v e b e e n d e s c r i b e d b y R o y a n d O s b o r n

( 1 9 5 2 ) , a n d R o y , R o y , an d O s b o r n ( 1 9 5 3 ) .

I n a s e r ie s o f a b o u t 1 0 0 r u n s t h e s e g e ls y ie l d e d o n l y s a p o n i t e a n d m o n t m o r i l -

l o n it e f r o m a b o u t 2 0 0 ~ u n d e r w a t e r p r e s s u r e s o f f r o m 1 0 ,0 0 0 t o 2 5 ,0 0 0 p s i i n

r u n s v a r y i n g f r o m a f e w h o u r s t o t h r e e w e e k s i n d u r a t i o n . A b o v e 3 5 0 ~ t al c ,

s il ic a , a n d c h l o r i te p h a s e s w e r e f o u n d t o b e s ta b l e. T h e s e p r o d u c t s c o r r e s p o n d

t o t h o s e f r o m o t h e r g e ls i n t h is c o m p o s i t i o n a l r e g i o n ( F i g . 1 ) . A t 1 0 0 ~ a n da t m o s p h e r i c p r e s s u r e t h e a u t h o r s p r e v i o u s l y h a v e s h o w n t h a t g e l s o f m o n t m o r i l -

l o n i t e c o m p o s i t i o n , o n r e f l u x i n g w i t h w a t e r f o r m o r e t h a n s i x m o n t h s , y i e l d

m o n t m o r i l lo n i t e . T h e a t t a p u l g i te a n d s e p io l it e g e ls w e r e h e a t e d t o a b o u t 3 0 0 ~

u n d e r 2 0 , 0 0 0 p s i w a t e r p r e s s u r e a n d q u e n c h e d a f t e r o n l y 8 a n d 2 4 h o u r s i n



1 4 0 NEW DATA ON SEPIOLITE AND ATTAPULGITE

TABLE 2. - - ATTAPULGITE AND SEPIOLITE SPECIMENS

No. Mineral Locality

1H-43 Attapulgite Attapulgus, Geo rgia1H-46-1 Attapu lgite Qu incy, FloridaK Attapulgite Ko reaC Sepiolite Cornw all, Pennsylvan iaS.L.U. Sepiolite Gou verneur, New Y ork

290719 Sepiolite Jehoi, M ongolia250884 Attapulgite Mt. Co ok , Vene zuela2100400 Attapulgite M etaline, W ashington

1 A.P.I. Reference Clay Collection.2 U .S. National Mu seum sample numbers.

h o p e s o f m e t a s t a b l y f o r m i n g t h es e m i n e ra l s, b u t o n l y m o n t m o r i l lo n o i d p h a s e s

r e s u l t e d .

S i n c e a l l e f f o r t s to c r y s ta l l iz e a t t a p u l g i t e a n d s e p i o l it e f r o m s y n t h e t i c s t a r t i n g

m a t e r i a l s f a i l e d , o n e p o s s i b l e c o n c l u s i o n i s t h a t t h e s e m i n e r a l s a r e n o t s t a b l e

p h a s e s i n t h i s s y s t e m i n t h e p r e s e n c e o f e x c e s s w a t e r . O f c o u r s e , i f li m e i s a n

e s s e n t ia l c o n s t i t u e n t o f t h e s e m i n e r a l s , t h e i r e q u i l i b r i u m r e l a t i o n s a r e t h e r e b y

r e m o v e d f r o m th e sy s te m M g O - A 1 2 0 3 - S i O 2 - H 2 0 . F u r th e r w o r k o n r e l ev a n t

p o r t io n s o f t h e q u i n a r y s y s te m C a O - M g O - A 1 2 0 3 - S i O z - - H 2 0 is c o n t e m p l a te d .S e v e r a l n a t u r a l s p e c i m e n s h a v e a l s o b e e n s t u d i e d u n d e r h y d r o t h e r m a l c o n -

d i t i o n s i n o r d e r t o i n v e s t i g a t e f u r t h e r t h e s t a b i l i t y r e l a t i o n s o f t h e s e m i n e r a l s ,

a n d t h e s e a r e d e s c r ib e d i n T a b l e 2 . T h e r e s u lt s i n d i c a t e d i n F i g u r e 2 s h o w t h a t

e v e n a t t e m p e r a t u r e s a s l o w a s 2 0 0 ~ u n d e r 2 0 , 0 0 0 p s i w a t e r p r e ss u r e , w el l-

c r y s t a l l i z e d a t t a p u l g i t e s a n d s e p i o l i t e s b r e a k d o w n i n t o w e l l - c r y s t a l l i z e d "ex-

p a n d i n g " s a p o n i te a n d m o n t m o r i l l o n i te s t ru c t u re s . A t t e m p e r a t u r e s h i g h e r

t h a n a b o u t 3 5 0 ~ q u a r t z , t a lc , a n d c h l o r it e p h a s e s a p p e a r . O n t h e o t h e r h a n d

a t t a p u l g it e ( U S N M 1 0 0 4 0 0 ) a n d se p i o li te ( S . L . U . ) r e m a i n e d u n a l t e r e d a f te r

t h r e e m o n t h s t r e a t m e n t i n b o i l i n g w a t e r a t a t m o s p h e r i c p r e ss u r e s . X - r a y p o w -

d e r m e t h o d s i n d i c a t e t h a t a t t a p u l g i t e s a n d s e p i o l i t e s r e m a i n a p p a r e n t l y u n a f -

f e c te d b y h y d r o t h e r m a l tr e a t m e n t b e l o w 2 0 0 ~ f o r as l o n g a s t h r e e w e e k s, b u t

e l e c tr o n m i c r o g r a p h s s h o w s m a l l b u t n o t i c e a b l e a r e a s o f f u z z in e s s o n th e e d g e s

o f t h e f ib e r s w h i c h w e r e n o t a p p a r e n t i n t h e u n t r e a t e d s a m p l e s.

T h e r e su l ts o f d r y , s t a ti c h e a t 1 t r e a t m e n t s f o r p e r i o d s o f 2 4 h o u r s a r e i n d i-

c a t e d in F i g u r e 3 . S e p i o li te a n d a t t a p u l g i te r e m a i n e d a l m o s t u n a f f e c t e d u p t o

a b o u t 4 0 0 ~ w h e r e a ll b u t a f e w o f t h e s t r o n g e s t d i f f r a c t i o n p e a k s d i s a p p e a r e d .

T h e i n te n s it ie s o f t h e se r e m a i n i n g p e a k s w e r e g r e a t l y d i m i n i s h e d . A t a b o u t

1 After this paper was completed the work of Brauner a nd Preisinger (19 56) came to ourattention. It should be noted that the suggestion tha t reversibly remov able zeolitic water isevolved only up to 250~ wou ld explain bo th earlier references (loc. cit.) to "zeolitic" waterand our inability to find any such water at 400~ These authors have presented the mo stdetailed crystal structure w ork on sepiolite as yet attempted. Th ey hav e also indicated th atsepiolite occurs in several serpentine deposits and ha ve stressed the structural relationshipsbetween the parent serpentine minerals and the sepiolite derived therefrom.



FRED A . MUM PTON AND RUSTUM R oY 141

S E P IO L IT E 2 0 0 ~ s o p o m l e 3 5 0 ~ t a l c + ?

A T T A P U L G I T E ~ m o ntm o rillo nite 3 5 0 ~ s i li c a + t a l co r p y r o p h y l l i te+ c h t o r i t e

FIGURE2 . - Results of hydrothermal treatments at 20,000 psi water pressure for periodsfrom one to three weeks.

SEPIOLITE 400~ f e w l i n e s l e f t 70 0~ "X- ray amorphous"

I 1 5 0 ~c r i s t o b a l i te + e n s t o t i t e

ATTAPULGITE 400~ few l ines le f t 7 0 0 "C "X- ray amorphous"

)lS---O~ cris?obolite + cordierite

FIG UR E 3 . - - R e s u l t s of dry, static heating of sepiolite and attapulgite for 24-hour periods.

7 0 0 ~ t o 9 0 0 ~ t h e sa m p l e s a p p e a r e d a l m o s t x - r a y a m o r p h o u s e x c e p t f o r t h e p e r -

s i s te nc e o f a c a l c i t e pe a k a t ~ 3 . 02A . A t 1150~ c r i s t oba l i t e a nd e ns t a t i t e w e r e

f o r m e d f r o m t h e s e p io l it e , a n d c r i s to b a l i t e a n d c o r d i e r i t e f r o m t h e a t t a p u lg i t e.

N o t r a c e o f t h e "s e p i o l it e I I " o r t h e " a t t a p u l g i t e I I " o f M i g e o n ( 1 9 3 6 ) a n dL o n g c h a m b o n ( 1 9 3 7 ) ( s u p p o s ed l y f o r m e d a b o v e 4 ~)0 ~ w a s f o u n d .

O B S E R V E D F I E L D R E L A T I O N S O F A S E P I O L I T E F R O M B A L M A T ,

N E W Y O R K

I n A u g u s t 1 9 56 , a n o p p o r t u n i t y p r e s e n t e d i t se l f f o r t h e e x a m i n a t i o n o f a

s e p io l it e l o c al it y . W i t h t h e k i n d p e r m i s s i o n o f t h e G o u v e r n e u r T a l c C o m p a n y

t he oc c u r r e nc e o f s e p i o l i t e i n a t a l c - t r e m o l i t e body a t Ba l m a t , S t . L a w r e nc e

C o u n t y , N e w Y o r k , w a s s tu d i e d . T h e m i n e r a l o c c u r s a s s p o n g y c o a t in g s o n

m o s t o f th e f r a c t u r e , c l e a v ag e , a n d j o i n t s u r f a c e s a s w e ll a s o n m a n y " b e d d i n g

s l i p s " be tw e e n m a s s i ve t r e m o l i t e b l oc ks i n s e ve r a l d r i f t s o f t he m i ne . W he n t h i s

w a t e r - s o a k e d m a t e r i a l i s d r i e d t h e c h a r a c t e r i s t i c l e a t h e r y t e x t u r e b e c o m e s a p -

p a r e n t . T h e r e s ee m s t o b e n o r e l a t i o n b e t w e e n th e c o n c e n t r a t i o n o f t a lc a n d

t h a t o f th e s e p io l it e . S e p i o l it e a p p e a r s t o h a v e b e e n d e p o s i t e d f r o m g r o u n d

w a t e r a n d i s obv i ous l y l a te r t ha n e i t he r t he t a l c o r t he t re m o l i t e . A pos s i b l e

e x p l a n a t i o n i s t h a t t r e m o l i t e h a s b e e n a t t a c k e d b y g r o u n d w a t e r , b r e a k i n g d o w n

i n t o a l m o s t c o l l o i d a l s i z e p a r t i c l e s w h i c h a r e t r a n s p o r t e d b y a n d r e d e p o s i t e d

f r o m the g r ou nd w a t e r a l ong jo i n t s , f r a c t u r e s , e t c. T he s e c o l l o i da l pa r t i c l e s r e -

t a i n a s t r u c t u r a l m e m o r y i n h e r i te d f r o m th e p a r e n t a m p h i b o l e , t r e m o l i te . L o w -t e m p e r a t u r e c r y s t a l li z a ti o n a r o u n d t h e se n u c l e i c a n r e a s o n a b l y l e a d t o s e p io l it e.

T h e p r e s e n c e o f a b u n d a n t l im e a t t h is l o c a l it y w a s c o n f i r m e d , b u t t h e q u e s t io n

o f it s e f f e c t s ti ll r e m a i ns t o be so l ve d . S e p i o l i t e ( S . L . U . ) f r o m t h i s m i ne w a s

r e a d i l y c o n v e r t e d t o s a p o n i t e a t a b o u t 2 2 5 ~ u n d e r h y d r o t h e r m a l c o n d i ti o n s .



1 4 2 N E W D A T A ON SEPIOLITE AND ATTAPULGITE

S U M M A R Y A N D C O N C L U S I O N S

F r o m a n an a l y s i s o f t h e e x p e r i m e n t a l d a t a o b t a in e d f r o m b o t h n a t u r a l s a m -p l e s a n d s y n t h e t i c g e l m i x t u r e s , s e p i o l it e a n d a t t a p u l g i t e a p p e a r t o b e m e t a s t a -

b l e p h a s e s w i th r e s p e c t t o s a p o n i t e a n d m o n t m o r i l l o n i t e , a t l e as t in t h e s y s t e m

M g O - A 1 2 O s - S iO 2 - - H 2 0 . U n d e r h y d r o t h e r m a l t r e a t m e n t n a t u r a l s a m p l e s a n d

g e l m i x t u r e s y i e ld e x p a n d i n g m o n t m o r i l l o n o i d s a b o v e 2 0 0 ~ w i t h n o i n d ic a -

t io n o f t h e f o r m a t i o n o f s e p io l it e o r a t ta p u l g i t e b e l o w . A t l o w e r t e m p e r a t u r e s

( 1 0 0 ~ m o n t m o r i l l o n i t e c a n b e s y n t h es i z ed , w h i l e n a t u r a l se p i o li te a n d a tt a -

p u l g i te a r e n o t r a p i d l y d e s t r o y e d . T h u s , i t c a n b e d e m o n s t r a t e d u n e q u i v o c a l l y

t h a t a b o v e 2 0 0 ~ m o n t m o r i l l o n i t e a n d s a p o n i t e a r e m o r e s ta b l e t h a n s e p io l it e

o r a t t a p u l g i t e ; t h i s i s m o s t p r o b a b l y t r u e e v e n a t 1 0 0 ~ F u r t h e r m o r e , i t i s u n -

l i k e ly t h a t t h e s e s t a b i l i ty r e l a t io n s w i l l b e r e v e r s e d b e t w e e n 1 0 0 ~ a n d r o o m

t e m p e r a t u r e . T h e p o s s i b i l i t y r e m a i n s t o b e i n v e st ig a t e d , h o w e v e r , t h a t t h e

p r e s e n c e o f C a O m a y a l t e r t h e s t a b i l i t y r e l a t io n s , a l t h o u g h i t i s t o b e n o t e d t h a t

t h e n a t u r a l s a m p l e s , c o n t a i n i n g a n y C a O t h e s t r u c t u re " n e e d s , " w e r e c o n v e r t e d

t o m o n t m o r i l lo n i t e s b y h y d r o t h e r m a l t r ea t m e n t .

W h e r e t h e y a r e a s s o c i a t e d w i t h w e a t h e r e d p y r o x e n e s a n d a m p h i b o l e s , a t t a -

p u l g i te a n d s e p io l it e a r e t h e r e f o r e q u i t e l i k e ly t o h a v e b e e n f o r m e d b y t h e

g r o u n d - w a t e r a l t e ra t i o n o f t h e se c h a i n s t r u c t u r e m i n e r a l s a t lo w t e m p e r a t u r e s .

T h e r e a s o n f o r t h e f o r m a t i o n o f a m o u n t a i n l e a t h e r m i n e r a l r a t h e r t h a n m o n t -

m o r i l lo n i t e o r t a lc m a y b e a s c r i b e d to s t r u c t u ra l c o n t r o l f r o m t h e p a r e n t a m p h i -b o l e o r p y r o x e n e . T h e o r i g i n o f e i t h e r s e p i o l it e o r a t t a p u l g i t e i n s e d i m e n t s a n d

s o i ls i s s t i ll i n d o u b t , a l t h o u g h t h e r o l e o f s t r u c t u r a l c o n t r o l ( a n d t h e p r e s e n c e

o f l im e ) m u s t b e a n i m p o r t a n t f a c t o r . I t w o u l d a p p e a r t o b e h i g h l y u n l i k e ly t h a t

a m o n t m o r i l l o n o i d w o u l d b e c o n v e r t e d t o a t t a p u l g i te o r s e p io l it e .

A C K N O W L E D G M E N T S

I t i s a p l e a su r e t o a c k n o w l e d g e t h e s u p p o r t o f t h is r e s e a r c h b y t h e A m e r i c a n

P e t r o l e u m I n s t i t u t e t h r o u g h a g r a n t - in - a i d . T h e a u t h o r s a r e i n d e b t e d to t h e

G o u v e r n e u r T a l c C o m p a n y f o r t h e i r c o o p e r a t i o n i n t h e f i e ld i n v e s t i g a t io n o f

s e p io l it e . T h a n k s a r e a ls o d u e to D r . G e o r g e S w i t z e r o f t h e U . S . N a t i o n a l M u -

s e u m f o r n u m e r o u s s a m p l e s o f b o t h s e p i o li te a n d a t ta p u l g i t e .

R E F E R E N C E S

Bowen, N. L. , and Tut t le , O. F. , 1949, The sys tem MgO-SiOz-H.~O: Geol . Soc . Amer . , Bul l .60 , p . 439 460 .

Bradley, W. F. , 1940, Th e s t ructura l scheme of a t tapulg i te : Am er . Min. , v . 25 , p . 405-410.Brauner , K. , and Pre i s inge r , A. , 1956 , Th e s t ruc tu re and o r ig in o f sep io l i te : Tsch e rm aks

mineralog, u. petrog. Mitte. (Vienna), v. 6, p. 120-140.Cai l l6re , S. , 1936, Som e asbest i form and papy raceo us s i lica tes not be longing to the ant i -

gor i te group: Bul l . Soe . Franc . Min. , v . 59 , p . 352-374.Cai l l~re , S., 1951, Sep iol i te : in X -ray identi fica tion and crys ta l s t ructures of c lay mine ra ls ,

Mineralogical Society, London, p. 224-233.Cai l l~re , S., 1951a, Pa lygo rski te-a t ta pulg i te : in X-ray ident if ica t ion and crys ta l s t ruc tures

of c lay m inera ls , M inera logica l Socie ty , London, p . 234-243.



F R E D A . M U M P T O N A ND R U S T U M R o Y 1 4 3

Cai l l~ re , S ., and H6 nin , S . , 1949 , Occ ur rence o f sep io l i te in the L iza rd se rp en t ine : Na tu re ,v. 163, p. 962.

Geras imov , N. P . , Grushko , T . E . , and C h i rv insky , P . N. , 1949 , M inera l pa lygorsk i tovo ig rupp y iz so l ikamskogo gor izon ta kungursk ogo ya rusa v zapadnom Pre dura le : Vsesoyuz .Miner. Obshch., Zap., v. 78, no. 2, p. 95-100.

Heys tek , H. , and Sch mid t , E . R. , 1953 , The m inera logy o f the a t tapu lg i te -m ontm or i l lon i tedepos i t in the Sp r ingb ok F la t s , T ra nsva a l : Geo l . Soe . S . Afr ica , T rans . , v . 56 , p . 99 -119.

K a u f f m a n , A . J . J r . , 1 94 3 , F ib r o u s s e p io l i te f ro m Y a v a p a i Co u n ty, A r i z o n a : A m e r . M in . ,v. 28, p. 512-520.

K err , P . F . , 1937, At tapu lgu s c la y: Am er. Min. , v. 22, p . 534-550.Ke r r , P . F . , and o the rs , 1949 , An a ly t ica l da ta on re fe rence c lay min era ls : in Refe re nce c lay

minera ls , A. P . I . Res . P ro jec t 49 , P re l im. Rep t . 7 , 161 p .LaCro ix , A. , 1940 , Les t rans fo rmat ions min&alog iques seconda i res obse rv~es dans le s g i se -

men ts de ph logop i te de l ' ex t reme -sud de Mada gasca r : Com pt . Rend . Acad . Sc i ., v . 210,p. 353-357.

L a p p a r e n t , J a c q u e s , d e , 1 9 3 6 , L e s m i l i e u x g S n & a te u rs d e l a m o n tm o r iU o n i t e e t d e l as~p iol i te : Com pt. Rend . Acad . Sci . Paris , v . 203, p . 553-555.L o n g c h a m b o n , H e n r i , 1 9 3 5 , S u r l e s c o n s t i t u a n ts m in & a lo g iq u e s e s s e n t i el s d e s a r g i le s , e n

par t ic u l ie r des te r res ~ fou lon : Com pt . Rend . Acad . Sc i . Pa r i s , v . 201, p . 483-486 .L o n g c h a m b o n , H e n r i , 1 9 3 7, Ca r a c t& i s t i q u e d e l a s ~ p io li te d ' A m p a n d a n d r a v a e t l a f o r m u le

des s6pio l i tes : Bull . Soc. Franc. M in. , v . 60, p . 232-276.M igeon , G. , 1936, Se piol i tes : Bull . Soc. Fran c. M in. , v . 59, p . 6-134.Mu mp ton , F . A. , and Roy , Rus tum, 1956 , The in f luence o f ion ic subs t i tu t ion on the hydro-

the rmal s tab i l i ty o f montmor i l lono ids (ex t . abs . ) : in Clays and c lay minera ls , Na t . Acad .Sc i . - -N a t . Res . C ounc i l pub . 456 , p . 337-339.

Nagy , Bar tho lomew, and Brad ley , W. F . , 1955 , The s t ruc tu ra l scheme o f sep io l i te : Am er .Min. , v . 40, p . 885~92.

Roy , D. M. , and Roy , Rus tum, 1955 , Syn thes is and s tab i l i ty o f minera ls in the sys tem MgO-

AhO~-SiO~-H~O: Am er. Min. , v , 40, p . 147-178.Roy , D. M. , Roy , Rus tum, a nd Osborn , E . F . , 1953 , The sys tem MgO -ALO a-H~O and in f lu -ence o f ca rbona te and n i t ra te ions on the phase eq u i l ib r ia : Am er . J . Sc i ., v . 251, p. 337-361.

Roy , Rus tum , and Osborn , E . F ., 1952 , Som e s imple a ids in the hydro the rm al inves t iga t ionof mine ral sys tem s: Econ. G eol. , v . 47, p. 717-721.

Serdyuch enko , D. P . , 1949, Sep io l i te f rom nor th e rn Cau casus : Dok lady A cad . Nauk S .S .S .R. ,v. 69, p. 577-580.

Shanno n , E . V. , 1929 , Tsche rmig i te , am mo nio ja ros i te , epsomi te , ce les t i te , and p a l igorsk i tef rom sou the rn U tah : U.S . Na t . M us . P roc . , v . 74 , a r t . 13, 12 p.

Yod er , H. S . J r . , 1952 , Th e M gO-AI~Oa-S iO~-H_.O sys tem and the re la ted metam orph icfac ies: Am er. J . Sci . , Bow en voI ., p . 569-627.

2006 - New Data on Sepiolite and Attapulgite

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