Canodian Mineralogist
Vol. 23, pp. 21-28(1985)
DOYLEITE,A NEW POLYMORPHOF AI(OH)3,AND ITS
RELATIONSHIP
TO BAYERITE,GIBBSITEAND NORDSTRANDITE*
GEORGEY. CHAO ANDJUDITH BAKER
Departmentof Geologt, CarletonUniversity,Ottawa,Ontario KIS 586
ANN P. SABINA ANDANDREW C. ROBERTS
GeologicalSurveyof Canada,601Booth Street,Ottawa,OntarioKIA 0E8
associde
i calciteet pyrite dansdesfilonnetsd'albitite dans
la sy6nitendph6liniquedu mont St-Hilaire (Qu6bec)et d
weloganite, cryolite, calcite et quartz dans des sills de
Doyleite, a new polymorph of AI(OH):, occurswith cal- silicocarbonatitei la carridre Francon d MontrSal (Qu6cite and pyrite in albitite veinsin nephelinesyeniteat Mont
bec). Une analysepar voie humide donne: Al2O3 65.290
St. Hilaire, Quebec and in silicocarbonatitesills with
(en poids), CaO 0.48, H2O (par TGA jusqu'd 1100'C)
weloganite,cryolite, calcite,quartz and other mineralsar 35.76,total 101.44,soit Ale.eCae.el(OH):.00.
La doyleile
the Francon quarry, Montreal, Quebec.A wet-chemical est inerte dansles acidesHCI I :1, H2SOaet HNO3 a temanalysis gave: AI2O3 65,2, CaO 0.48, H2O (TGA to
p6ratureambiante.Une 6tuderadiocristallographiquesur
ll00'C) 35.76, sum l0l.M w1..0/0,
correspondingto
monocristaldu mont St-Hilaire r6vblela sym€trietriclinique;
Ale.eeCa6.s1(OH)3.ee.
The mineral is not attacked by l:1
son groupe spatialPT est d6termindpqrrsa morphologie,
HCl, H2SO4or HNO3 at room temperature.A single- a 5.A02Q),b s.t7s(r), c 4.980(2)A, c 97.50(l)', 0
crystal X-ray study showedthe mineral from Mont Sr.
1I8.60(l)', t lM.74(l)' , ponrZ = 2. Lescinqraieslesplus
Hilaire to be triclinic, spacegrolp PT from morphology, intenpesdu clich6de diffraction (m6thodedespoudres)[d
a s.N2(r),b s.175(1),
c 4.980Q)
A, a e7.s0(l),B I18.60(l), en A(r)(hkDl sonr: 4.794(100)(010),2.360_(40)(10l),
-1 104.74(1)",Z 2. Thg strongestfive X-ray powder- 1.972(3q(nD, 1.857(30xll1) et 1.842(30)(r?2).Les
diffraction lines [d in A(IX&k/)] are: 4.794(100)(010.y, cristaux, aplatis sur (010), prdsententles formes {010},
2.360(40X101),t.972(30)(221),1.857(30X111)and {l0l}, {l0l} et, danscertainscas,{100} et {001}. Ils sont
1.842(30)(122).
Crystalsaretabular on (010),showingforms
blancs, d'un blanc cr6meuxou bleudtre, allant de trans{010}, {101}, {101} and, occasionally,
{100}and {001}. parentsou translucidesd opaques,d ralure blanche,d'6clat
They are white, creamywhite or bluish white, transparent vitreux, nacr6 ou terne. Duretd 2y, d 3, densit6, 2.48
or translucentto opaquewith a white streak. Their lustre (mesurde),
2.482(calcul6e).Le clivageestpadait sur {010},
is vitreous,pearlyor dull, Mohs hardness2/z - 3, D(meas.) distinctsur { 100}.Biaxepositif, a I .545(l),0 I .553(l),r
2.48(l), D(calc.) 2.482 g/cmz. Cleavageis perfect on
1.566(l), 2V=77' (Na). Orientation de l'indicatrice
e:r coordonndes sphdriques (d, p): X(90", 4L'),
{010}, fair on {100}. Optically,the mineralis biaxial posi
tive,o 1.545(l),B 1.553(l),r 1.566(1),
2V : 77oin Na light.
YQ,40",53"),2(343",74), avecc (0,0)et r* (0,900).L'anaOrientation of indicatrix in sphericalco-ordinates({, p):
lyse thermogravim6triquer6vdle une perte de poids de
x(90",41.),-y(2N",53.), Z(i43.,74"), with c (0,0)and)*
25.63V0entre 280 et 4l0oC, et une autre perte, graduelle,
(0,90'). TGA showeda weightlossof 25.6390between280 jusqu'A 1000"C(total 35.76V0).
Le spectred'absorption
and 410'C, and a further gradual loss to l000oC, giving infrarouge ressembled ceux de la gibbsite et de la norda total weightlossof 35.7690.The infraredabsorptionspec- strandite, quoique plus simple. On pr6dit la structure de
trum of doyleite is similar to but simpler than those of
la doylei'tei partir de cellesde la gibbsite et de la nordgibbsiteand nordstrandite.Its structureis predictedfrom
not6esdans
strandite,en sefondant sur desressemblances
the known structuresof nordstranditeand gibbsiteon the
Le polymorphisme
deuxzonessur lesclich6sde pr€cession.
basisof similaritiesin X-ray precession
photographsin two
r6sultede diffdrencesd'empilementdesfeuillets d'octaddres
zones.Polymorphism in AI(OH)3 results from different
A(OH)6. Le nom rapelle E.T. Doyle, d'Ottawa.
ways of stacking the layers of AI(OH)6 octahedra.The
mineral is named after E.T. Doyle of Ottawa, Ontarid.
(Traduit par la R6daction)
ABSTRACT
Keywords: doyleite, aluminum hydroxide, new mineral,
Mont St. Hilaire, Francon quany, Quebec,structural
relationship, bayerite, gibbsite, nordstrandite.
Mots-clds: doyleite, hydroxyde d'aluminium, mont StHilaire, carribreFrancon, Qu6bec,relationsstructurales,
bayerite, gibbsite, nordstrandite.
SoMMAIRE
INTRODUCTIoN
La doylei'te,nouvqlu polymorphede AI(OH)3, setrouve
*Publication 16-84 of the Ottawa-Carleton Centre for
GeoscienceStudies.
2l
The formerly unidentified mineral UK45 from
Mont St. Hilaire, Quebec (Chao & Baker 1979) has
been established as a new polymorph of aluminum
hydroxide on the basis of X-ray diffraction, chemical and electron-microprobe analyses and optical
22
THE CANADIAN MINERALOGIST
studies. The unknown no. 11 from the Francon
quarry in Montreal, Quebec,reported by Sabina
(1979),has also beenshownto be the samemineral
as UK45 according to results of X-ray powderdiffraction and electron-microprobeanalyses.The
mineral is named doyleite after Mr. E.J. Doyle of
Ottawa, Ontario who found the Mont St. Hilaire
material. The mineral and its name have been
approvedby the Commissionon New Minerals and
from Mont
Mineral Names,I.M.A. Type specimens
St. Hilaire are depositedin tho collectionsat the
National Museum of Natural Sciences,Ottawa,
Ontario (NMNS 48932) and at the Royal Ontario
Museum, Toronto, Ontario (M41025). Specimens
from the Francon quarry are preservedat the Geological Survey of Canada, Ottawa, Ontario.
OccunnsNcs
The mineral occursat Mont St. Hilaire asrosettes
of platy crystals (Fie. l) lining a wg in a vein in
nephetnesyenite.The matrix rock, albitite, is almost
wholly composedof albite with lessthan 590 siderite and minor amountsof pyrite, molybdenite,zircon and fluorite. Within the vug, the only associated
minerals are calcite and a small amount of pyrite.
The doyleitecrystalsare in placescoatedwith a thin
film of dark brown amorphousmaterial, probably
iron oxide. Some doyleite rosetteshave a core of
albite. Underlying the doyleite rosettesthere is a narrow (l-5 mm) but distinct reaction-zone,suggesting
that doyleitewas depositedfrom a later generation
of fluids after the emplacementof the vein.
At the Francon quarry doyleite occurssparingly
in vugsin silicocarbonatitesills intruding Ordovician
limestones.The mineral is finely granular, forming
pulverulent to compact globules, bolryoidal and
smooth porcelainlike crustsand sheetscommonly
on weloganite,calcite,quartzand lesscommonlyon
cryolite and strontianitecrystals.In somecases,the
original calciteor cryolite crystalshavebeenpartly
or completelyleachedout, leavingshellsof doyleite.
The mineral is generallyadmixed with unknown No.
3 (Sabina1979),believedto be an aluminumhydroxide with an X-ray powder pattern similar to that of
gibbsite.Other associatedmineralsare albite, dresserite, dawsonite,fluorite and analcime.
CnvstalrocnePnv
Eight crystalsand crystal fragmentsfrom Mont
St. Hilaire were studied by single-crystalX-ray
diffraction using a precessioncamerawith various
zone-axesof the crystalsas the precessionaxis. The
photographs show doyleite to be triclinic, space
group Pl or PT. The centrosyrnmetricspace-group
is suggestedby the morphology of crystals. The
reducedcell wasestablishedin a computersearchof
the shortesttranslation vectorsin direct space.The
cell parametersobtained werethen refined by a leastsquaresmethod using Gandolfi X-ray-diffraction
data. The refined cell-parametersand X-ray powder
data of doyleitefrom Mont St. Hilaire and Francon
are comparedwith those of other polymorphs of
A(OH)3 in Tables I and 2. The reduced cells of
doyleite and nordstrandite are usgd in Table I to
accentuatethe differencesin cell geometry of the
polymorphs.
of a perfect{010} cleavage
ofthe presence
Because
the conventional Debye-ScherrerX-ray powderdiffraction pattern shows a strong preferredorientation effect that causesvariations in relative
intensitiesof the 0k0 lines.The 020reflection,which
has a low to medium intensity on the single-crystal
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photographs,is either absentor too weak to be measured on the Gandolfi photographs but is always
presenton the Debye-Scherrer
photographs;its relative intensity varies from 5 to 20.
The crystals of doyleite from Mont St. Hilaire
(Fig. l) aretabular on (010)and boundedby {l0l}
and {101} pinacoids,giving rise to a nearly square
outline. On somecrystalsthe {100} and {001} pinacoids are also present,modifying the shapeof the
platesto different degreesdependingon the prominence of these forms. A centre of symmetry is
apparent.
The material from the Francon quarry is very fine
grained. The scanning-electronmicroscopeshowsthe
Fro. 2. Doyleite from the Francon quarry, Montreal
Island, Quebec.Scalebar l0 pm.
crystalsto be platy with pointed terminations@ig.
2), resemblingthe common habit of nordstrandite
(Chao & Baker 1982).
PHYSICALAND OPTTcALPnopsnttrs
Doyleite from Mont St. Hilaire is colorlessand
transparentto translucent,with a vitreousto pearly
lustre and a white streak. The mineral from the Francon quarry is white, creamywhite or bluish white,
translucentto opaquewith a dull lustre. The Mohs
hardnessis about 2Vzto 3. The density of doyleite
from Mont St. Hilaire, determinedby flotation in
a heavyliquid, is 2,48(l) g/cm3, in good agreement
with the calculated density of 2.482 g,/cm3.The
crystalplatesare slightly flexiblebut not elastic.The
mineral is not fluorescentin long- or short-wave
ultraviolet light. It is not solublein l:1 HCI, HrSOa
or HNO3 at room temperature. In addition to a
perfect {010} cleavage,a much lessdistinct {100}
cleavagehas been observedon some crystals.
Optically, doyleiteis biaxial with a 1.545(l),B
1.553(1),
r 1.566(l),2V : 77" (meas.),76.8o(calc.)
in Na light. The orientation of the indicatrix, with
respectto [001] and (010),is shownin Figure 3 and
is defined by the spherical co-ordinates (S,g)
X(90",41"), Y(240", 53"), 2(343",74') with c(0,0)
and b*(0,90"). In white light the mineral shows
moderatelystrong dispersion,r > v.
CHEMICAL COMPOSITION
A hand-pickedsampleof doyleitefrom Mont St.
Hilaire was leachedwith weak HCI to removethe
iron-oxide coating on somegrainsand analyzedby
conventionalwet-chemicalmethodsfor major ele-
24
THE CANADIAN MINERALOGIST
T A B L E3 .
Al 203
5i0r
Ca0lilg0
Fe0
Na20
Hzo
Total
64.8
0.01
0.16
0.08
35.76
63.7
0.03
0.14
0.09
Jl. /o
100.81 99.72
C O M P O S I T IOOFND O Y L E I T E
63.f
0 .t 2
65.2
0.48
0.21
0.06
Jt. /o
Ja. /o
59.6
3.22
nta
0.96
0.08
0.35
35.56
65.36
34.64
99.25 101.44 100.00 100.00
analyses by P. Jones. H20 by TGA.
4 . f , l o n tS t . H i l a l r e , Q u e b e c . l { e t - c h e m i c a la n a l y s i s b y B o n d a r Cleqa& Co. Ltd. Hro bv TGA.
5 . r r a n c 6 i q u a r r y , I ' l o n t r E a l ,Q u e b e c , A v e r a g eo f f o u r
e l e c t r o n - n i c r o p r o b ea n a l y s e sb y I . B o n a r d i , G S C .
C o f f e c t e d a g a i n s t g i b b s l t e l n t e r n a l s t a n d a r d . H 2 0b y
di fference.
6 . C a l c u l a t e d f o r t h e o r e t l c a l A 1( 0 H ) 3 .
Mont St. Hitaire show that the dehydrationbegins
at about 200'C:,the maximum rate of dehydration
occursbetween280' and 4l0oc, with a weightloss
Frc. 3, Opticalodentationof doyleite.
of 25.63t/oat 425oC. Thereafter, the dehydration
continues at a much slower rate, leveling off at
at I100'C is 35.7690.
1000'C.The total weight-loss
ments. The water content was determinedby ther- On cooling from 425"C to room temperaturethe
mal gravimetric analysis to l100oc. The results partly dehydratedmineral regainssomeof the lost
water, giving a net weight-lossof 1890, approxi(Table3, no. 4) correspondto Alo.eeca0.or(OH)3.00.
The Mont St. Hilaire material was also analyzedby mately one half of the water in the mineral. X-ray
electron microprobe using a seriesof ten-second diffraction showsthe partly dehydratedmaterial to
be essentiallyamorphous,with faint dilfuse linesof
counts,a defocusedbeam,and natual gibbsite(Al),
anorthite (Ca), albite (Na, Si) and olivine (Fe, Mg) 7-Al2O3,indicating a completedestruction of the
of the formaas standards.K and Ti werelooked for but werenot doyleitestructureand commencement
detected.The Francon material was analyzedby elec- tion of 7-Al2O3.The final product of dehydration
tron microprobeusinga broad beamand a moving- quenchedfrom ll00oC is 1-Al2O3in three casesbut
sampletechniquewith syntheticcorundum (Al) and it is corundum with a trace of an unidentifiedphase
kaersutite(Si, Ca, Mg, Fe, and Na) as standards. in another. The sampleusedin the latter analysismay
Resultsof four analyses,correctedagainstthat of have been slightly impure.
The infrared absorption spectrumof doyleitefrom
a natural gibbsiteinternal standard,wereaveraged.
No other elementswith Z > 1l were found. The Mont St. Hilaire is comparedwith that of nordstranwater contentof the Franconmineralwasnot deter- dite and gibbsitein Figure 4. The spectrumof doymined owing to the small amount of pure material leite is characterizedby its simplicity in the OHavailable. The electron-microprobedata are com- stretching(3300-3700cm-r), OH-bending(700-1100
pared with the resultsof the wet-chemicalanalysis cm-r) and AlO-stretching (200-600 cm-r) regions.
The differenceis attributable to the fact that there
in Table 3.
The Gladstone-Dale calculations (Mandarino is only one crystallographically independent
1979),usingthe resultsof the wet-chemicalanalysis AI(OH)6 octahedron in the doyleite structure,
whereas there are two in the nordstrandite and
normalizedto 10090, gave Kp/Kg:0.223/0.253
: 0.881.The large discrepancybetweenKr and K6 gibbsite structures.
could not be accountedfor by experimentalerrors
Srnucrunel RpLattoNstltP to
of indices
in the chemicalanalysisor measurements
Ornnn A(OH)3 MtNPnars
possible
that
strucIt
is
density.
of refraction and
tural configurationssuch as packing and hydrogen
a perfect cleavage,which is
Doyleite possesses
bonding may play an important role in this case.
common to the other AI(OH), minerals, for
instance,{001} in gibbsiteand {110} in nordstranTHSRMAI- ANALYSES AND
dite (Chao & Baker 1982).Although cleavagein
INFRARED ABSoRPTIoN SPncrnurra
natural bayerite from Hartrurim, Israel (Gross &
The TGA and DTG analysesof doyleite from Heller 1964)wasnot reported,Debye-Scherrerpho-
25
DOYLEITE, A NEW POLYMORPH OF A(OH)3
.9
.9
E
c
o
F
38 36 34 32 30 28 26 24 22 20 19 l8 17 16 1s 1/ 13 12 r',r 10 9
Wovenumber cm{x100
8
7
6
5
Frc. 4. Infrared absorption spectraof doyleite (a), nordstrandite(b) and gibbsite (c).
tographs of synthetic bayerite show a strong
preferred-orientationeffect for 00/ reflections,suggestingthat a perfect {001} cleavageis alsopresent.
photographof
Furthermore,the Glevelb-precession
doyleite is nearly identical to the 0-level tll0lprecessionphotograph of nordstrandite, and both
are very similar to the c-precessionphotograph of
gibbsite.Therefore,thereis little doubt that doyleite
also has a layered structure with the layers of
A(OH)6 octahedra essentiallysimilar to those in
gibbsite (Saalfeld & Wedde 1974), nordstrandite
(Saalfeld& Jarchow 1968)and bayerite(Yamaguchi
& Sakamoto1958,Rothbaueret a|.1967). Hence,
the structural relationship of doyleite to other
AI(OH)3 mineralscan be deducedfrom the geometry of its unit cell in relation to the cellsof other polymorphs: This is shownin termsof the structuralcell
of gibbsitein Figure5, wherethe pseudotrigonalcell
of bayerite(Montoro l942,Yasngtchi & Sakamoto
1958)is shown by dashedlines and the true monoclinic cell (Rothbaueret al. 1967)is approximated
by the gibbsitecell with q and b interchanged.The
doyleitecellis shownby dottedlines.The nordstrandite cell is approximatedby that of gibbsitewith a
and b of gibbsite correspondingto [T0] and -c,
respectively.Based on the near-identity of the ,precessionphotographof doyleiteand the [110]precessionphotograph of nordstrandite,the x and
e atomic co-ordinatesof doyleite can be predicted
from the atomic co-ordinatesof nordstrandite(Rothbauerel al. 1967)to two decimalplaceswith confidence.
Similarly, the OJevelI l0l]-precessionphotograph
of doyleite is nearly identical to the 0level cprecessionphotograph of nordstrandite and the
photographofgibbsite. Thusthe
0Jevelb-precession
projection of the doyleitestructurealong [l01] must
be almost identical to that of nordstranditealong c
and that of gibbsitealong b. Therefore,they atomic
co-ordinatesof doyleite can be determined. The
structure of doyleite so derivedis shown in Figure
6, whereit is comparedwith that of bayerite,gibbsiteand nordstrandite.To facilitate comparison,all
structuresare shown with respectto a gibbsite-like
cell, with the projectionsmade along the rxes correspondingto d of gibbsite.
The polymorphism in A(OH)3 is a result of
different ways of stacking octahedral layers, as
shownin Figure 6. In bayerite,eachlayer is stacked
directlyabovethe layerbelow. In gibbsite,the stacking is similar to that in bayerite, but every second
layer is turned upsidedown, creatingz-glide planes
and 21 axesbetweenthe layers. In nordstqandite,
layersare displacedby 1.70A along
the successive
-b of gibbsite, whereas!n doyleite the successive
layersare shifted by 1.95A along D of gibbsite.The
26
THE CANADIAN MINERALOGIST
bs-5.oA
r\
C' / _ _ _ _ _
t'
(d
Gn--------->
Frc. 5. Idealizedstructure of gibbsite projected on (001), showing geometricrelations of the cellsof gibbsite(solid lines),bayerite(dashedlines), doyleite(dotted
lines)and nordstrandite.Subscripts:g for gibbsite,d for doyleiteand n for nordstrandite.The oxygenatomsareat heightsof 0.1I (shadedlargecircles)and -0.1 I
(unshaded).
shifts of the layersin the directionscorrgsponding hedral layers are possible; for example, displacelayersalong a or - a of gibbsite
to a of gibbsiteare r^elativelysmall, 0.53 A in nord- ment of successsive
or mixed doyleite-nordstrandite,doyleite-bayerite
strandite and 0.32 A in doyleite.
Theoretically, other schemesof stacking the octa- and nordstrandite-bayerite layers are possible.
27
DOYLEITE, A NEw POLYMORPH oF A(OH)3
7\il
(o
(o
-l\,
ffi\t;
(\l
1
tllllH
(f)
!---
\
=
l'-
III|
oi
o
tl
ll
o
ol
II
o
II
i\z
I
I
/\1
*8=5.06
A*
7\t ffit
t
I
I
I
I
I
o)
o)
I
I
o'
_, t,
(b)
ffi \il,
tl
tR-
*b=5.028 A*
(a)
:_5\
I
\
I
I
I
I
I
I
I
N
I
ll
@
I
,o
'//k -;
I
I
I
I
::--
I
F
ol
@
I
I
tt
t
t//,
-\
* c = 5 . O 74
(c)
- [ i 0 i ] =5 . 0 9 6
(d)
Frc. 6, Idealized structuresof (a) bayerite, O) gibbsite, (c) nordstrandite and (d) doyleite viewed along a' of the gibbsitelike cellswhich are relatedto the respectiveadoptedcells(Table l) by 010/100/002,lM/010/001, I 10,/001/ll0 and
tOltTOIttZt. Shadedoctahedraare approximatelyat heights of 2/6 and 4/6, unshaded,l/6 and 5/6.
"Triclinic hydrargillite" (Saalfeld1960),which has
largevaluesof a and b, could perhapsbe explained
by such mixed layers in an ordered arrangement.
ACKNOWLEDGEMENTS
The authorsthank Drs. R.C. Erd and E.E. Foord
for critically readingthe manuscript, P. Jonesand
M. Bonardi for electron-microprobeanalyses,D.A.
Walker for a SEM photomicrograph (Fig. 2) and
ProfessorH. Saalfeldfor providing precessionphotographs of his "triclinic hydrargillite" for comparison. This study is supportedby NSERC grant
A5113to G.Y. Chao.
28
THE CANADIAN MINERALOGIST
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&-
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YaueoucHr,
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Received May 30, 1984, revised manuscript accepted
July 10, 1984.