American Mineralogist, Volume 58,pages46G470, 1973
TheCrystalStructureof Latiumite,a NewTypeof SheetSilicate
Erro CnNxrrro, A. Dlr NBcno,Grusnrrn Rossr
C.N.R. Centrodi Studioper la CristallografiaStrutturale,
cf o Istituto di Mineralogia,uia Bassi4,27100 Pauia,Italy
Abstract
The crystal structure of latiumite, Kor.Ca"(Si"rrA1r..)O,,(SO,)or(COr)n
sl a = 12.06, b
5.08, c - 10.81A, B = 106";spacegroup P2r, Z - 2, has been determinedon an Albano
specimen,using Weissenbergdata. The isotropic least-squaresrefinement led to a final R-index
of 0.08.
The main structural feature is the presence of double layers of (Si,Al) tetrahedra; the
double layers,parallel to the cleavageplane (100), are connectedto each other by Ca-atoms
and SO"- groups. The Si and Al atoms are ordered among the five symmetry independent
tetrahedra.A pseudo-glideplane results in frequent twinning on (100).
-
Introduction
Latiumite was discovered by Tilley and Henry
(1953) in some ejected blocks found in the 'peperino' of the Albano Hills near Rome. A tentative
interpretation of the chemical analysis of latiumite
(analyst J. H. Scoon) is given by the same authors
(Table 1, columns1 and 2).
The optical properties of latiumite are unusual:
the optic axial angle is variable, sectionswith lower
extinction angle being optically positive, those with
higher extinction angles optically negative; mottled
extinction is always present and zoning occurs frequently. Tilley and Henry explained these optical
features with the assumption that the mineral is a
solid solution series,but no correlation with chemical compositionwas made owing to the small number of chemical analyses.
A second Italian occurrence of latiumite was
reported (Barbieri and Fornaseri. 1970) in metamorphic ejected blocks found in a pumice deposit
near Pitigliano (Grosseto, Tuscany). The mineral
from Pitigliano has different optical properties: the
optic axial angle is constant, the optic sign is always
negative, and the refractive indexes are lower. Unfortunately Barbieri and Fornaseri gave no chemical
analysisof this latiumite.
(\", : 1.54051A) using the multiple film technique.
A total of 1350 reflections (84%) of the 1612 present
in the CuKa limiting sphere were inspected; the
intensities of 877 reffections were measured photometrically, the remainder being too weak to be
conveniently measured.
Cell parameters were re-determined from Weissenberg and oscillationphotographs:a :.12.06 + 0.01,
6 : 5 . 0 8 + 0 . 0 2 ,c : 1 0 . 8 1+ 0 . 0 1A , I : 1 0 6 . 0 " ;
these valuesare in fair agreementwith those published
by Tilley and Henry except for B (106' us 108").
The systematic absencesof 0k0 reflections with
=
k
2n * 1 restricted the choice of the space group
to P21/m or P21. In the course of the structure
analysis the correct space group proved to be P2y
The measured intensities were corrected for Lorentz and polarization effects but no absorption correction was applied. The correction suggested by
Sakurai (1962) for incomplete resolution of the
Ka doublet was applied with the replacement of
Y for d (Buerger's notation) in the interpolation
formula.
Crystal Structure Analysis
The statistical averages and distribution of the
normalized structure factors are given in Table 2
where they are compared with the theoretical values
for both a centrosymmetric and a non-centrosymExperimental
metric distribution of atoms in the unit cell (Karle
A small prismatic crystal of latiumite from Albano
et al, 1965). Since no conclusive indication as to
was used for recording the X-ray data. Weissenberg space group can be drawn from Table 2 or from a
photographs (rotation axis b) of five reciprocal piezoelectricity test, it was assumed initially that
lattice layers were recorded with CuKo radiation
latiumite was centrosymmetric. An attempt was
466
467
LATIUMITE, A NEW TYPE OF SHEET SILICATE
Tesr,B|.
ChemicalCompositionof Latiumite
TlnLB 3.
Atomic Coordinates and Isotropic Temperature
Factors of Latiumite*
From chenlcal analyses*
wt. i4
Atoos to 0=25
Fron structure
analysls**
lrE, Z
Atons to F29.4
sio2
28.33
23.4L
4.3
T(1)-slo.toAro.ro
Al-2o3
24,67
26.32
5.7
r(2)-Ar
.3816 (4)
Fe2O3
0,50
0.07
r(3)=sio,50A1o.5o
.3447 (4)
FeO
0,55
0 .0 9
r(4)-sio.ssAlo.r5
MnO
0.02
MgO
0.76
CaO
29.4L
Mult.**
5.32
.3497 (5)
0.00 (8)
.2bore5)
.47E4 (s)
o.0s (8)
.7Lo3(23)
0.13 (9)
.7494(27)
0(1)
o(2)
0(3)
0(4)
.6900(13)
.5165(10)
.3379(L2)
.33S9(11)
.0804(43)
,7269(46)
.0531(41)
.5388(37)
'0583(15)
.r03s(12)
.0460(14)
.1934(13)
1.21(28)
0,75(22)
0,79(25)
0.47(24)
0(5)
o(5)
0(7)
0(8)
.3414(13)
.5299(11)
.3073(L2)
,2426(12)
.0920(42)
.7277(50)
.5754(40)
,Lr73(42)
.3428(L4)
.4097(13)
.4166(14)
.s358(r3)
r.02(25)
0.9s(23)
0.8s(26)
0.80(25)
o(9)
0(1-o)
o(11)
.9407(13)
.8350(12)
.7475(12)
.5sr9<42)
.029e(40)
.5974(40)
.3981(1s) 1.34(30)
.3s40(14) 0'68(26)
.2166(13) 0.6s(24)
tat-
ca(l)
ca(2)
ca(3)
.8866 (3)
.2025 (3)
.1166 (3)
.2581(23)
.2549(22)
.7384(23)
.1913 (3)
.1450 (4)
.4srs (3)
0'33 (5)
0.82 (7)
0'22 (5)
D . = 2.88***
carc
K
s
l.7o (s) .5741(5)
r.42 (5).03s8 (s)
.2574(29)
.7833(27)
.2748(6)
,1387(6)
r.20(17)
0.44(L7)
0(12)
o(13)
o(14)
0(r5)
.8170(46)
.9119(14)
1 . 3 5 ( 1 0 ) . 1 0 5 9 ( 1 7 ) .3298<49)
.s317(50)
, 0 5 4 9( r 7 )
.0703(r6) -o.0107(48)
.0803(r7)
.045r(20)
.20r.8(2r)
.2388(19)
2,16(37)
0.49(50)
2.30(42)
1,75(38)
0.2L
30.48
0.40
Kro
7.2O
L,73
7. 2 5
HzO
O.27
so3
5.42
0.76
10.15
coz
1.60
0.40
0.14
99.98
0.02
??o
6.0
r.4
0.6
Less 0=C1 0.03
= 2.92**x
o.t7 (8)
.758L(27)
.8239 (4)
,5530 (4)
r(5)=Ar
1.11
D ,
carc
0.o7to (4)
0.7soo
.3559 (5)
.0840 (s)
Na2O
cl
B(A')
U,tb
o.3i7s (4)
*AnaLAei,s published by lilley
J.H-.
anl Hewy (7952)' amlAst
one of
ttn partial
atwlyees:
Scooh. The resuLts ate frm
but 303, C02, CL; the
pure materi,al for alt the elments
of
a uexy waLL ftaction
bther ueirq "a product containLn4
lns been subjeet to amlysis'tl
nelilite
uhich itsel'f
**Chmical
of
eomputed on the basis of tle relults
amlysis
the structure
detemimtion.
rr*D^,^ = 2.93 (From Tilley and Henry, 1952).
oDs
made to solve the crystal structurein spacegroup
P21/m by the reiterative application of Sayre's
equation using an unpublishedprogram by Long
0.60
.01
0.77
0.08 (8)
.17
* Estinat ed standard
dep iations
in paventhe 6 e s.
**The nultipliers
shoMd
uhich in the cou?se of the refinanent
tt@n ore stanlad
ualues
snaller
the
ezpeeted
deuiqtions
fron
udLue af 2,
and Lnue the theoretical
deuiation
are onitted
*rrThe panmetere
of this aton a?e those 4f the center of the
These patmetets
0(14) and 0(75).
by 0(12),
triangle
fomed
to tar!
in the eourse of the refirenent.
not alloued
aere
sive structure-factorcalculationsand three-dimenrevealedthe atomsthat were
sionalFourier syntheses
The set of signswith the highestconsistencywas
E
map
and confirmedthe structhe
not detectedon
usedto computean E map. The highestpeaksaF
the 'heavy' atoms were
positions
all
of
ture. The
peared in the sectionswith y nearly equal to I/4
consistentwith spacegtoup P2t/m, thus explaining
and3/4; a numberof smallerpeaks,doubledby the
the initial successof the E map obtainedwith the
mirror plane, produced unreasonablyshort intercentrosymmetricassumPtion.
atomic distances.These difficultiesled to the conrefinement
Five cyclesof full matrix least-squares
that the
siderationof spacegroupP21.By assuming
factors
lowtemperature
isotropic
with
individual
peaksat y = l/4 and ), - 3/4 corresponded
to the
'heavy'atomsSi, Ca, K, and by suitablyinterpreting ered the R-index to 0.081 for the 877 measured
reflections.An attempt to use anisotropictemperathe peaks doubled by the mirror, it was posprobably becauseof
ture factors was unsuccessful,
sible to constructa structuralmodel in P21.Succesthe unfavorableratio of number of variables to
Test"n 2. Statistical Av_erages.andDistribution of E for
number of observations.Consequently,the refinement was stoppedat the last isotropiccycle.A secExperimental
CenErlc
Acentric
ondary extinction correction (Zachariasen,1963),
<lEl>
0.846
0. 886
introducedin the last two cyclesof the refinement
0.798
(g = 1.53 x 10-G),reducedR from 0.094to 0.081.
.lr'- rl'
0 , 73 6
0.886
0.969
Refinementwas carriedout using a locally modi. l e 'I '
1.0
1.0
1.0
'l
version of the program oRFLSby Busing et a/
fied
E>1
33.5 7"
32.0 %
36.8
(1962).
The scatteringfactors were for neutral
L,8 %
E> 2
5.0 "/.
from Hansonet al (1964).
taken
atoms,
E>3
0.3 7"
0 . 0 Lz
0.0 "t
(r96s).
).q
/6
468
CANNILLO, DAL
Tesrn 5.
r(1)-o(l)
o(2)
0(l)
o(4)
nean
r(2)-o(4)
0(r)
o(6)
0 (7 )
Interatomic Distancesof Latiumite*
1.65(2);
1,62('t\
1.66(2)
1,62(1)
1.64
1 . ? t ( 1)
1.76(2)
1 . ? l ( 1)
1. ' t 4 ( 2 )
mean 1.74
r(l)-o(r)
0(6)
o(?)
0(8)
nea
1.69(2)
1.66(1)
i.69(2)
1.69(2\
'1
. 68
c a ( r) - o ( r) z , s z ( z ) i
o(s) 2,62(2\
o(10)
o(11)
o(12)
o(13\
o(14)
o(15)
2.13(2)
2.47(2)
2.60(2)
2.62(2)
z.j4(2\
2.53(2)
nean
2.5 j
ca(2)-o(3)
0(4)
o (t )
a(l2)
a(13)
o(14)
o(15)
2.4o(1)
2.r1(2\
2.46(2)
2.48(2)
2,5r(2)
2.38(2)
2,50(2)
5 - O ( 12 )
0(11)
o(14)
o(15)
mean 1.63
aeaE
1.78(2)
1 . ? 8 ( 1)
1.72(2)
1.75(2)
1,74
nen
K - o ( 1)
a(2)
o (2 ) '
0(5)
o(6)
o(6),
o(?)
o(8)
o(10)
0(11)
neu
3.r6(z)
2.98(2t
3.24(2)
3.21(2)
2.93(2)
1.18(2)
3.19(z)
3.1r(2)
3.23(2)
2.91(2t
1.12
2,47
c-o
ca(l)-o(?)
o(8)
o (9 )
o(9)'
o(10)
0(14)
a(15)
1.46(2\i
1.50(2)
1.45(z)
1.48(2)
mean 1.47
nea
r ( 4 ) - 0 ( 8 ) 1 . 6 5 ( 1)
0(9) 1.58(2)
0(10)1.63(2)
o(11)1.6t(2)
r ( 5 ) - o ( 1)
0(2)
o(l)
0(11)
NEGRO, AND
1 . J?x*
2.49(1)
2,47(2)
2.25(2)
2.50(2)
2.28(2)
2.80(2)
2.55(2)
2.48
xEstinated
stsdard
deviatj.ons
in parentheses.
i*lhis
value
correspond.s
to the di.stuce
of the center
fron
the vertices
of the trimgle
fomed by 0(12),0(14)
md O(15).
Final atomic parameters are given in Table 3.
The observed and calculated structure factors are
compared in Table 4.1 Bond distances and angles
are listed in Tables 5 and 6.
Description and Discussion of the Structure
Latiumite is a sheet silicate, as Tilley and Henry
had supposed. Corrugated double layers of tetrahedra connected by Ca atoms represent the main
structural feature of this mineral. The SO+r- groups
act as 'bridges' between calcium atoms linked to
different double layers.
The aluminosilicate layer. Each single layer (Fig.
1) is formed by rings of six and eight tetrahedra;
the adjacent layer is superposedon the first by screw
rotation in such a way that the eight-memberedring
of one sheet is connected with a six-membered ring
of the other. In this way four of the five independent
tetrahedra share all their oxygen atoms, while the
remaining tetrahedron, Z(4), has only two shared
oxygens. Note that if the Z(4) tetrahdra were elimi'To obtain a copy of Table 4, order NAPS
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ROSSI
Tesrn 6.
o ( 1) - r ( 1 ) - o ( 2 )
0(l)
0(4)
o(2)-r(1)-o(l)
0(4)
0 ( 3 ) - r ( 1) - 0 ( 4 )
Tetrahedral Bond Angles of Latiumite*
1 1 2 . 8( 8 ) o
1 0 ? . 9( 9 )
1 0 8 . 7( 9 )
109.9(10)
108.2(7)
1 0 9 . 3( 8 )
0 ( 4 ) - r ( 2 ) - 0 ( 5 ) 1 0 6 . 9( 8 )
1 0 9 . 4( ? )
o(6)
o(7)
1 0 6 . 3( 8 )
o ( 5 ) - r ( 2 ) - o ( 6 ) 11 o . 2 ( 1
i )
o(7) r11.2(8)
0(6)-r(2)-0(7)'112.5 (9)
o ( 5 ) - r ( 3 ) - o ( 5 ) 1 1 2 . 1( 9 )
1 0 7 . 8( 8 )
o(7)
1 0 4 . 9( 9 )
o(8)
o(5)-r(3)-0(?) 114.2(11)
o ( 8 ) 1 0 ? . 4( 8 )
o ( 7 ) - r ( 3 ) - o ( 8 ) 1 0 9 . ?( 8 )
0 ( 8 ) - r ( 4) - 0 ( 9 )
10 1 . 0 ( 9 )
o ( 1 0 ) 1 1 0 . 9( 9 )
0 ( 1 1) 1 0 6 . 9 ( 8 )
o ( 9 ) - r ( 4 ) - o ( 1 0 ) 1 1 6 . 2( 9 )
o ( 1 1 ) 1 0 8 . 2( 9 )
o ( 1 0 ) - r ( 4 ) - o ( 1) 11 1 0 . 9 ( 9 )
xEstimated. stmdard
d.eviations
o ( 1) - r ( 5 ) - o ( 2 ) 1 1 1 . 8 ( 1 O ) o
0(3) r08.4(8)
0(11)
1 1 4 . 2( 8 )
o ( 2 ) - r ( 5 ) - o ( 3 ) 1 1 0 . 0( 8 )
0(11)
107,' (1)
o ( r ) - r ( 5 ) - o ( 1 1 1) 0 4 . 6 ( 8 )
r ( 1) - o ( 1) - r ( 5 )
r ( 1) - o ( 2 ) - r ( 5 )
r ( 1) - o ( 3 ) - r ( 5 )
r ( 1) - 0 ( 4 ) - r ( 2 )
r(2)-0(5)-r(3)
r ( 2) - o (6 ) - r ( i )
r(2)-0(?)-T(l)
r(3)-o(8)-r(4)
r ( 4 ) - o ( 1)1- T ( 5 )
12 2 . 5( 1O )
159.5(10)
125.3(9)
12 6 . 6 ( 1 o )
12 0 . 7 (1O )
15 4 . 1 (10 )
1 2 0 . 8( 9 )
13 2. 9 ( 12 )
13 2 . r ( 1 2 )
o(12)-s-o(13) 111.o(11)
o(14) 111.2(13)
0(15) 106.3(12)
o(11)-s-o(r4) 110.2(11)
0(15) 106.3(12)
o(14)-s-o(15) 107.1(11)
in parentheses.
natedand if
and T(5) were joined together,
"(3) identical to the aluminosilicate
the sheet becomes
layer in hexagonalCaAlzSizOe(Takeuchiand Donnay,1959).
The double layer can also be visualizedas rings
of five tetrahedrarepeatedby the screw axis (Fig.
2). Theseringsare nearlyparallelto (010), and the
resulting double layer is parallel to (100), which
is a planeof perfectcleavage.
On the basisof the relationshipbetween7-O distancesand Al contentsgiven by Smith and Bailey
(1963), it has been possibleto determinethe distribution of Si and Al in the five independenttetrahedra (Table 3).
The calcium-sulfate layer. Three independent
csing
Flc. 1 Single tetrahedral layer projected along [100].
LATIUMITE,
A NEW TYPE OF SHEET SILICATE
unit. Ca(1)
calciumatomsoccurin the asymmetric
is surroundedby eight oxygenatoms,while Ca(2)
and Ca(3) have sevenfoldcoordination.Some of
the oxygenatomslinked to Ca belongto the aluminosilicate layer, others belong to the SO1'- groups,
Ca(3) connectstwo silicatedoublelayersdirectly,
whileCa(1) and Ca(2) performthe samefunction
indirectly with the SO12-groups acting as bridges
betweenCa atomslinked to difterentdouble layers
(Fig.2), The Ca atomsand the sulfateions form a
positively-charged
layer which is sandintermediate
wichedbetweenthe negatively-charged
silicatelayers.
the
atoms
were
allowedto
The multipliersof
Ca
refinementbut did not
vary during the least-squares
greaterthan
showany deviationfrom full occupancy
one standarddeviation,
The meanS-O bond lengthin the SO+tetrahedron
(1.4'7 A) is in good agreementwith the values
reported recently for several sulphate structures.
The multipliersof S and O(13) are smallerthan
the theoreticalvaluesby severalstandarddeviations
(Table 3), while the remainingoxygenatomsof the
SO1tetrahedron
havea full occupancy.
This observation suggests
a partialsubstitution
of CO,r2for SO+3-,
which agreeswith the chemicalanalysis.The three
oxygenatomsshowingfull occupancyshouldbelong
to both the SO+2-and COr'- groups.An attemptto
find the carbon atom on the electrondensitymap,
near the centerof the triangleformed by O(12),
O(14) and O(15), provedunsuccessful,
probably
becauseof its low atomicnumberand overlapping
of the sulfurpeak.The partialoccupancy
of O(13)
only slightlydisturbsthe coordination
of Ca(1) and
Ca(2\.
Potassiumatoms occur in cavitiesbetweentwo
superposed
five-membered
ringsof tetrahedrain the
silicatedoublelayer.The K-O distances
rangefrom
2.91 to 3.24 A rnd the potassiumoccupancyis
about 85 percent.
The chemicalformula. The chemicalformula
resultingfrom the crystalstructureanalysiscan be
written rs follows:
K , rs ; C a , 3 ( S1i z; A l 2g ; O 1 1()S O + ) o, ( C O r ) n . 1 ,Z = 2 .
The chemical analysis,computed on the basisof this
formula (Table 1, column 4 and 5) differs from that
given by Tilley and Henry (Table 1, column 2 and
3) mainly in regard to its lower SiO2 content, and
its higher SO3 content. Unfortunately the available
material was insufficient to carry out a new chemical
analysis.
A fairly satisfactory balance of electrostatic
Frc. 2. The crystalstructnreof latiumiteprojectedon (010).
valences (Table 7) can be computed using the
method of Donnay and Allman (1970) and the
chemical formula obtained from the structure analy s i s .O n l y O ( 1 0 ) , O ( 1 4 ) a n d O ( 1 5 ) h a v e d e v i a tions greater than 10 percent from the formal value
of two positive chargesreaching each oxygen atom.
The unbalancedoxygens are involved in Ca-O distances which are well below, for O(10), or above,
f o r O ( 1 4 ) a n d O ( 1 5 ) , t h e C a - O a v e r a g ed i s t a n c e s
of their respectivecoordinationpolyhedra.There are
severalcases,for example,buergeriteand omphacite
(Martin and Donnay, 7972), where similar efiects
occur. The unbalancingof some oxygen atoms seems
to be due to the fact that with the Donnay and Allman approach the bond strengths of the shorter
bonds are underestimatedand those of the longer
ones are overestimated.
Tilley and Henry supposedthat latiumite was a
solid solution series.If so, its generalformula can be
written, on the basis of this structure determination,
a s K ( C a , N a ) : r ( A l , S i ) . . ' O (r S
' O + , C O , r ) .T h e m i n e r a l
analyzed in this work is hence an Al-rich member
of the series.An amount greaterthan three Al atoms
per formula unit would imply the replacementof Ca
by some trivalent cation or of K by Ba. On the other
hand a complete replacementof Al by Si and of Ca
by Na would not be possiblewithout changesin the
structure because some oxygen atoms would be
heavily unbalanced.Some such substitutionscould
possibly take place, but only additional occurrences
of latiumite will establish the limits of the solid
solution series.
470
CANNILLO,
DAL
NEGRO, AND ROSS/
Tesr.B 7.
(A)
kngths
and
Valences (V.U.)
Bond
T(1) T(2) T(r) T(4) !(5) ca(1) ca(2) ca(t)
Acknowledgments
The authors are much indebted to professor C. M.
Gramaccioli who made possible this investigation by pro.
viding us with the fine specimen of latiumite from Albano.
References
Bennrenr,M., ANDM. FonNespnr(1970) Un nuovo ritrova_
mento di latiumite. Rendiconti della S.I.M.p. 26, 427_
431.
BusrNg W. R., K. Menrrw, eNo H. A. Lew (1962) onrrs,
A Fortran crystallographic least-squares program. U.,S.
Nat. Tech. Inform. ,Seru., ORNL-IM-3OS.
DoNNAy, G., lNn R. AurvreN (1970) How to recognize
O-, OH-, and H*O in crystal structures determined by
X-rays. Amer. Mineral. 55. 1003-1015.
HeNsoN, H. P., F. HnnrvrlN, J. D. Lse, .lNo S. SrrrulN
(1964) urs atomic scattering factors. Acta Crystallogr.
17, 1040_7044.
Kenrn, I. L., K. S. DnecoNprrr, eNn S. A. BnswNen (19d5)
K
>cv
s
c
1.55
0. c1
1. 7 8 2 . 5 7
o.70 0.24
3,15
0.06
1.91
o(2)
1.62
0.98
1.72
o.?8
2.98
0.14
3.24
0.o3
1.91
1.65
0,91
1.72
O.?8
2.40
0.33
o(4) 1,621.1j
0.98 0.75
2.r1
0.28
0(5)
1 . 1 61 . 6 9
o.7l o.85
2.46
0.10
0(6)
t.1t 1.66
0.16 0,92
0(7)
1.141.58
0.75 0.85
1. 6 9 1. 6 5
0.86 o.92
0(8)
Twinning ol latiumite. Latiumite often shows
singleo,r repeatedtwinning with twin plane (100).
Twinning can be explained from a structural point
of view in the following way: a pseudo-mirrorplane
(103) is presentin each five-memberedring (Fig.
3 ) and also governs the Ca atorns directly bonded
to the ring; the combination of this pseudo-mirror
plane with the 2, screw axis results in a pseudo.n
glide-plane (100) which becomes the twin glideplane. Morphologically it appearsas a twin mirror
plane. The portion of the structure common to the
two individuals of the twin has Pmn2l pseudo.symmetry. The formation of the twin produces only
small distortions in the calcium-sulphatesubstructure.
Bond
0 ( 1)
0(l)
Fro. 3. Structural interpretation of twinning in latiumite.
The two individuals of the twin are related by the pseudoglide plane n.
Estimated
0(9)
1.58
1.O5
2,62
O.23
0( 10)
1, 6 1
0.95
2,1-r
0.35
o(1i)
1, 6 5 1. 7 5 2 , 4 1
o.92 0,74 0.28
2.O2
2.O2
J.21
0.04
1.93
2.9J
0 .1 8
t. 18
0.05
2,49 l. 19
0.28 0 . 0 5
1.94
2,41 l . 1 5
0.28 0 .d 5
2.12
1.91
2,25
0.38
2.ro
o,?7
2.24 3 . 2 3
O ,l ? 0 . 0 4
2.91
0.20
1. 9 3
1.12
2.14
0(12)
2.60 2,44
o,zJ O,29
1.45
1.08 00442.O0
o(11)*
2,62 2,5'
0.15 0.19
1.50
0.98
o(14)
2.54 2.18 2.8O
o,25 O,32 O.11
1.45
t , 1 1 O . 42 . 2 5
o(15)
2.rf 2.5O 2.5a
0.26 o,29 O.2'
1.48
1.01 0.4 2.21
zJtv
>Cv
,Av
1' l l
(1.90)
3 . 8 o 3 , o O1 . 5 0 3 . 8 5 l . o 0 2 . 0 0 2 . 0 0 2 . 0 0 0 . 8 5 4 . 2 0 1 . 2 2 9 , 4 0
= v4lence
= valences
of
bondlE
of
bond6
reechinE
endatlnq
eni.on.
fron
cation
6lmed
der
in
parentheaeE
the
bonded
anlons.
*
has
aton
lhis
extrapoleted
tl-'v
an
ocdlancy
to
frll
of 0,7i
occupilcy,
tlre
velue
is
the
The crystal and molecular structure of the serotonincreatinine sulphate complex. Acta Crystallogr. 19, 713716.
LoNc, R. E. (1965) The crystal and molecular stucture ol
cyclopropancarboxamide, Ph.D. Thesis, University of
California, Los Angeles.
MrnrrN, R. F., .rxo G. Douxey (1972) Hydroxyl in the
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Seruur, T. (1962) A nuclear quadrupole resonance and
X-ray study of the crystal structure of tetrachloro-hydroquinone. Acta Crystallogr. 15, 443447,
Surnr, L V., eNo S. W. BerrBy (1963) Second review of
Al-O and Si-O tetrahedral distances. Acta Crystallogr.
16,801-811.
Tereucul, Y., eNo G. DoNNly (1959) The crystal structure of hexagonal CaAlsSiOe, Acta Crystallogr. 12, 465474.
Trur-nv, C. 8., lNo N. F. M. HeNny (1953) Latiumite
(sulphatic potassium-calcium-aluminumsilicate), a new
mineral from Albano, Latium, ltaly. Mineral. Mag, 30,
39-45.
Ze,cuennseN,W. H. (1963) The secondaryextinction correction. Acta Crystallogr. 16, 1139-1144.
Manuscript receioed, August 8, 1972; rccepted
for publication, Ianuary 9, 1973'.