American Mineralogist, Volume 59, pages 900-905, 1974
Whitmoreite,
Fe'*Fe3.,(OH),(H,O)*[PO,],,
A NewSpecies:
Its Description
andAtomicArrangement
Peur B. Moonn, ANrHoNy n\ Xevrpr, nNn ANrnoNv J. InvrNc
Department of the GeophysicalSciences,The Uniaersity of Chicago,
Chicago, Illinois 60637
Abstract
Whitmoreite, ideally Fee*Fe"-,(OH),(H,O)olPOnl,,a 10.00(2) A, b 9.73(2), c 5.471(8),
p 93.8(1)', P2'/c, Z - 2, is a new speciesderived from the hydrothermal alteration of
triphylite from the Big Chief pegmatite, Glendale, South Dakota, and from the Palermo No. l,
North Groton and Fitzgibbon, East Alstead pegmatites, New Hampshire. The mineral occurs
as brown to greenish brown acicular crystals elongated parallel to [001] and twinned by
reflection parallel to {100}. The observed forms are a{l0o}, m{ttD}, s{011}, l{021}, and
u{llz}. The hardnessis 3, the cleavage is fair parallel to {100}, and the specific gravity is
2.87(r). Crystals are biaxial (-), o r.676(3), B r.725(4), t r.745(4), b llY, c lJz, pleochroism X,Y light greenish-brown, Z dark greenish-brown. Electron probe analysis providesFe 27.8,Mn 3.0, and P 13.0.
The crystal structure analysis lR(hkl).0.14 by visually inspected filmsl reveals a new
type of Fe'*-O octahedral condensation based on open sheetsof compositio,n [Fe*r(OH)r(Oe)ul.
These are linked by [POn] tetrahedra to form slabs parallel to {100} of composition
[Fe'*,(OH),[PO4],]L; the remaining tetrahedral vertices are corner-linked to trans-lFe2*(Or),
(H,O).] octahedra. These latter octahedra are (l) partly replaced by Mn'9* and (2) partly
oxidized, and accommodatethe averagepopulation,0.3l Fd* + O.27Mn* + 0.28 Fe"* + 0.14
Hole.
A network of hydrogen bonds is proposed, which is cut by the {100} plane.
Introduction
Our study is divided into two parts, the first a
description of the new species whitmoreite. Owing
to crystal-chemical complexities and the frequent
multiple roles of water molecules in secondary
phosphate crystals, the result of a crystal structure
analysis is a necessary part of any adequate description of a new species and the second half of
this paper is devoted to that study.
Occurrences and Paragenesis
In 1971, Mr. W. L. Roberts of Rapid City, South
Dakota, provided us with specimens of an acicular
unknown mineral encrusting siderite in corroded
triphylite from the Big Chief pegmatite near Glendale, South Dakota (Middle of E Vz, NE /a, sec.
22, T.25, R.6E). Almost simultaneously, acicular
tan crystals on siderite from the Fitzgibbon pegmatite, East Alstead, New Hampshire (collected by
the late Mr. Gunnar Bjareby of Boston) were
shown to be the same compound. Finally, in 1973,
Mr. Robert Whitmore (an amateur collector of
repute) of Weare,New Hampshire,brought to our
attention attractive specimensof an acicular radial
brown mineral from the Palermo No. 1 pegmatite,
N. Groton, New Hampshire, which proved to be
the same material. The parageneticsettings at all
these localities are practically identical, and the
following discussionderived from examination of
all samples.The Palermo No. 1 pegmatite is accepted as the type locality owing to the superior
quality of the crystals.The diagnosticresults derive
from a Palermo sample.
Whitmoreite occurs as thin acicular crystals five
to ten times as long as they are thick, which range
from 0.1 to 2.0 mm in length. Crystals are grouped
as fans and sprays but occasionallyoccur as isolated individuals. A typical appearance involves
a small spheroidal core from which radiate small,
thin crystals providing the appearanceof a burr
or a floating naval mine. These crystals are almost
invariably perched upon siderite rhombohedra in
open cavities. Earlier in the paragenesisare quartz
crystals,siderite,and occasionalludlamite and the
900
WHITMOREITE, A NEW SPECIES
901
later species include strunzite, laueite, beraunite,
mitridatite, and manganicand ferric oxy-hydroxides.
About forty specimenshave been examined; although whitmoreite cannot be regarded as an
abundantmineral at any of the localities, it appears
to be dispersed in small quantity throughout the
siderite paragenesiswhich derived from the alkalileaching and late stage carbonation of parent
triphylite.
Description and Properties
Physical Properties
Whitmoreite is pale tan to deep brown to
greenish-brownin color, being not unlike and easily
confused with the far more abundant childreniteeosphorite.The luster is vitreousto subadamantine
in the darker colored crystals.The crystals possess
a rhomboidal cross-section with a chisel-shaped
termination;casualexaminationsuggestsa pseudoorthorhombic development.The hardnessis 3 and
the cleavage{100} fair. Specificgravity, established
by sink-float in methyleneiodide-toluenesolutions
is 2.87 i 0.01; the computeddensityacceptingthe
cell contentsproposedfurther on, is 2.85 g cm-3.
Crystal Morphology
Single crystal X-ray study establishesthat whitmoreite crystals are usually twinned by reflection
parallel to {100}, which imparts an orthorhombic
habit to the crystals. Careful search among many
specimensfailed to reveal a discerniblesinglet.These
crystals almost certainly grew initially as twins but
rarely reveal repeatedtwinning, so that re-entrant
angles are infrequently encountered.The crystals
are long prismaticto acicularparallelto [001]. Twocircle goniometric study on crystals from the Big
Chief and Palermo No. 1 pegmatitesrevealed the
formsa { 100}, m {llD},s{O I I }, t {O2I}, andu {II2} .
Typical developmentsare presentedin Figure 1.
X-ray Crystallography
Powder, single-crystalrotation, and Weissenberg
and precessionphotographs,the data of which were
refined by least-squareson the indexed powder
lines,providedthe followingcell criteria:a l0.OO(2)
A, b 9.73(2)A, c 5.47I(8) A, B 93"49(6)',space
group P2r/c, Z = 2. In addition, a three-dimensionaldata set was gatheredon Weissenberg
photographs.Theseresultswere used to index the powder
data in Table 1.
t,
Frc. 1. Typical development of whitmoreite crystals
twinned by reflection on {100} showing the forms a{100}'
m{rro}, s{011}, t{021}, and u{r12}. A. Plan. B. Clinographic projection.
902
MOORE, KAMPF, AND IRVING
Tenrs 1. Whitmoreite. Powder Datai
T,/IO
d (obs)
d (calc)
IO
7
7
t0 .05
7.0r
9.98
6.97
l+.99
o
7
5
3
4 . 98
4.81
Lt lt2
lr 2l
t+
5
7
rl
+
z
3
2
I
3
3 . I + 76
?
?qR
3.09r
3. 0 0 0
2.878
2.802
2.726
2.585
2.46I
2. t]00
2.3r+9
2.264
2.222
t]47
4.4q
4. 20
3.463
3.366
3.085
3.000
2.876
2.804
2.720
2.46r+
2.400
2.3+7
2.266
2.222
hkl
100
1r0
200
020
zLO
lrt
I,/IO
I
I
4
3
J
3
izr
12I
130
22L
22L
3II
230
2
3
3
3
2
Ttz
202
32L
\zz
212
0tlI
2
2
2 . L 73
2.159
2.I01
2.OO7
1.982
I.959
l-.884
I.837
I.776
hkl
2.L7C
2.158
2.IOI
33r
corrected
for
4Il
222
I .7rs
1.681
l' I. 6 r + 4
q7q
1.555
1 . 53 2
I . r+89
t. 461
l.4tt8
T11r+.0 mm camera diameter,
sphere powder mount.
rolled
for absorption.
and sample coruected
shrinkage
The persistent twinning observed for whitmoreite
can be explained on the basis of the cell geometry.
The addition of a {100} reflection twin plane results
in nearly perfect superposition of (hkl) and (hkl) for
I : 4N, where N is an integer. Define 2t x a*.
Evidently, t : !c* sin(r/2 - p). From this equation.
2t : 0.0976 A-', which deviates about 3 percent
from ax : 0.1002 A.-'. Alternatively, accepting the
values of a* and c* from the cell data, (r/2 - p) :
3o55'. a calculated value which differs from the
observed ("/2 - p) : 3"49'by 6', which is within
the limit of experimental error. Thus, it is not possible
to separate(h, k, 4N) from (h, k, 4N) by any counter
diffractometric technique.
d (calc)
d (obs)
FiIm
cumulative analysis low by about 8 percent. This
formula, stated as oxides, computes to FeO 4.9,
MnO 4.2, FezOs 40.0, P2Ob 31.2, and HgO 19.7
percent.
Optical Properties
Whitmoreite is biaxial (-), o 1.676(3), B 1.725
(4), 1.745(4),2V
60-65o, and reveals nearparallel extinction with b llY and , llz. The
pleochroism is X, Y light greenish-brown, Z dark
greenish-brown. Th calculated mean index of refraction, (n) - L76, utilized the tables of oxide specific
refractive energies (Larsen and Berman, 1934), and
the Gladstone-Dale relationship.
Chemical Composition
Owing to the meager quantity of crystals, we
despaired of recovering enough material for wet
chemical analysis. Accordingly, it was proposed to
obtain metals by electron probe microanalysis and
derive water content and oxidation grade through
crystal structure analysis.
Several small crystals from the Palermo No. 1
pegmatite were submitted for analysis, utilizing
wyllieite as a standard. The results are Fe 27.8,
Mn 3.0, and P 13.0 percent; no other metals with
atomic number greater than oxygen were detected.
The proposed formula, discussed further on, provides Fe 31.8, Mn 3.3, and P 13.6 percent with the
Name
The mineral WnrrvronErrs is nam,ed in honor of
Mr. Robert W. Whitmore of Weare, New Hampshire, devoted collector of pegmatite minerals. Motivated by a keen interest in secondary phosphates,
he quite literally overturned the dumps of the abandoned Fletcher pegmatite, bringing to light many
fine specimens representing the complex phosphate
paragenesisof a now-classic locality.
The species and name were approved by the
International Commission on New Minerals and
New Mineral Names (IMA). The type specimen
has been deposited in the U.S. National Museum.
WHITMOREITE.
A NEW SPECIES
Whitmoreite: Its Atomic Anangement
Owing to the persistenceof twinning in whitmoreite and the relatively small size of the good
crystals,it was not possibleto secure a suitable
fragment for the three-dimensionaldata collection
by diffractometer.
Crystal structure analysis serves two important
purposesin the elucidation of species: the knowledge of the atomic arrangementwith the proposition of a precisestructuralformula; and the determination of bonding properties through interatomic
distances and angles. We decided to unravel the
whitmoreite structureby visual estimationof photographson a limited data set, sacrificingthe precision
usually obtained from the more sophisticateddiffractornetric techniques.Our results are sufficiently
accurate for unambiguous interpretation of the
structure.but the errors in bond distancesare about
:L0.03A. Consequently,we shall emphasizeonly
the salient features of the atomic arrangementin
this study.
903
and CuKB, on the two sets of films. These were
scaledand the resultsaveraged.The 402 independent
reflections were processedto obtain structure factors after Lorentz and polarizationcorrections.Since
the cross-sectionof the crystal was only 60 p x 60 p
and, sincethe scalefactor for eachlevel was varied.
we did not correct for absorption.
Solution and Refinement ol thc Structure
The three-dimensionalPatterson synthesis, P
(ursw), led to unambiguousinterpretationof the
two octahedral,Fe(l) and Fe(2), and one tetrahedral P cations.Fourier synthesiswith these three
atomsas input resolvedthe positionsof all the unique
remaining seven non-hydrogenatoms in the structure.
Least squaresrefinementon the lgr\,r370 computer
proceededfrom a local version of the familiar Onnrs
program of Busing,Martin, and Levy (1962).Fullmatrix scalefactors (one for eachlevel);multiplier for
Fe(l); and atomic coordinate and isotropic thermal
vibration parametersfor all non-hydrogenatomsconExperimental
yqrged to R(hkt)
tt
llF(obs)l
lF(calc)lll
0.14 for the 402 reflections. We
A small 0.06 x 0.06 x 0.2 mm twinned crystal t
lf(oboll
was mounted parallel to the c-axis and two sets of employedthe scatteringcurvesfor Fe'*, P" and O1Weissenbergfilms of the hkl to hk3 levels were proposedby Cromer and Mann (1968).The results
collected utilizing unfiltered copper radiation. The are listed in Table 2, and the structure factors are
films were exposed for 48 hours at 45 kV and presentedin Table 3. A final difference synethsis
15 mA, the film pairs separatedby an attenuating failed to revealany additional atoms in the structure.
foil of aluminum. Individual intensities were gathered visually with a linear spot scale graded from Topology and Geometry of the Structure
one to ten. Care was taken to selectonly those inWhitmoreite possessesa new type of Fe3*-O
tensitiesbelongingto the sameindividual.For each octahedral condensation,the essential features of
reflection,we obtainedfour readings,including CuKc which are shown in Figure 2. Each Fe3*-O octaTenr,s 2. Whitmoreite. Atomic Coordinates and Isotropic Thermal Vibration Parameterst
n(i2)
Atom
Te(r) = 0.58(Fe,Mn)2+ + o.28Fe3+
Fe(2) = 1.gFer+
. 3 0 2 7( 8 )
.3e3(2)
. 3 s e( 2 )
.rs8 (2)
.30'+(2)
P
o (r)
o (2)
o (3)
o (q)
qq6r2\
oll
o!.J(])
o!\' (2)
lEstlmated
0.0000
. 4 6 0 3( s )
errors
refer
to the last
digit.
o.o0o
.3qr(1)
r.e (3)
2 . 7( 2 )
. 4 2 s 6( 8 )
. 4 7 7( 2 )
.48r_(2)
. 4 8 2( 2 )
.262(2)
.325(2)
.r2r+(4)
. s7e(r+)
.275(4)
. 3 1 7( 4 )
o.7 (2)
1.6 (s)
2 .1 (s)
2.s(s)
2.e(s)
. 2 3 s( 2 )
. 0 7 6( 4 )
r _ . 6( s )
. 2 e s( r + )
. 1 8 8( r + )
3.I(6)
3.3(6)
- . I02 (2)
. 1 8 3( 2 )
(2)
. 13r+
.0r+7(2)
standard
0.0000
.1373(s)
MOORE, KAMPF, AND IRVING
904
Tesr-E,3. Whitmoreite. Structure Factors (h, t, F"b", F".r")
10.1
21.!
3 1 .q
27.6
22.C
26.9
21.!
f3.7
25.3
2s.q
51.9
2J.0
Il.6
r3.8
59.9
q3.6
r5.q
!.1
tt.2
2 r.0
u;.I
27.0
2i.0
qa . 0
J0.l
l3-I
22.)
lLr.t
I ).i
I ).q
l,).1
18.J
tt.7
2 2, ?
!.J
q!.0
2r.0
t:.0
t8,N
1.2
5t.L
2?.7
28-q
2b.q
!.3
9.1
9.?
9.1
8.!
22.S
t!.t
a.s
1I.2
2)"2
1.8
70.0
;q.t
9.1
2 3 .b
!1.2
7. 2
? 7- t
22.t
86"2
61.8
8-0
21"1
2!.i
tq.7
2/ .8
8I.9
5i.J
6.3
2,".\
21.5
30.7
28.6
J0.2
2 8 .q
29.1
l? -0
10.5
2t.q
7A.2
rr. l
9.8
L2.A
l!.0
?a.2
q].q
q0.q
2r.i
68.q
tq,6
!.0
16 .l
r9.6
t8.q
15.0
Ja.3
12.4
10.!
tt.t
2?.7
!.7
\7.t
2q.0
J!.L
I1.l
2L.O
!"3
52.1
1?.j
ql.7
20.7
23.r
Ll.t
1r.a
!.0
I8.2
2A.3
t0.l
16"l
I0.q
1r.I
l,r.r:
t2.s
?q.t
\.2
?2,1
c3.7
100.2
?r.2
lf.7
5q.t
20.4
q3-2
t2.8
5:.0
10.8
2t
"7
16"6
33.?
Ltq.b
7q.i
86.8
18.6
tf.9
3q.5
r0.q
Lt.7
28.3
6?.5
q6.3
48.C
64.2
10"?
45.3
12.+
51.7
fg.i
q2.8
47.2
30.0
2t.I
I0.2
II.O
26.9
36.7
13.6
13.8
Il.t
5C.6
12.5
56.5
\2.2
31.8
?2.?
t 3.5
ll.8
5l.t
[1.]
3.t
25.2
J6.6
3q-b
20.7
0.9
q.r
18.6
93.3
20.1
?9.8
56.0
22.2
\2.a
9.q
q6.q
25.8
22.6
18.1
q0.3
t?2.)
13.5
93.9
f9.0
3.9
11.8
17.5
0.2
22.\
6q.9
q3.0
q6,6
62.8
q.t
q0.?
6,9
+\.1
f0.5
16.0
86.I
26.5
2?.7
5.6
6.I
2q.1
J2.?
7.f
16. q
I.8
50.7
26,q
5!.5
36.I
28.8
I!.0
8.1
5.5
q6.0
57.3
35.9
3t.3
L3.7
13.8
13.8
q3.r
-l
-2
-3
-l
z0.e
6.q
f06,2
63.5
59.8
9.t
2s.0
21.q
Is,9
?2.q
I9.8
6.5
19.7
20.q
\7 .q
21.1
5.f
q.l
56.8
36.2
?9.6
22.7
5.7
\.7
tl.1
29.5
2q.l
I.2
129.8
6 9, 5
7E.a
6.8
3q.6
qt.6
31.9
59.3
\?.7
73.0
45.6
2f.9
Il.?
10-0
10.8
20.q
L2.1
23.\
t7.t
3I.7
L5.7
59.2
2I.8
65.6
f5.r
tt.o
2.c
+.9
?2.0
16.1
38.q
t1.0
31.0
18.C
73.0
2\.3
3q.5
lr.7
L2.2
f8"1
13.1
f3.7
21.6
78.3
38.7
29.5
f3.5
35.0
1"2
IZ.4
15.8
?.1
8.3
30.8
80.8
37.5
2A.?
5.7
31.8
3?.6
13.6
29.7
3f.2
6.2
13.8
13.8
13.7
22.A
6.r
If.7
I9.7
2.8
L=
2
hedron has four of its six vertices linked to other
equivalent octahedra. One pair of these constitutes
a s h a r e de d g e O ( 1 ) - O ( l ) t a n d t h e r e m a i n i n gt w o
corner-link via the (OH)- ligands. The two (OH)ligands occur on adjacent vertices so that they can
be regarded in cls-configuration with respect to an
octahedron. It is noted that the (OH)- linkages
define a stepJike corner-chain parallel to [001],
which is roughly the distance of two octahedral
edges. These chains share O(1)-O(1)t edges with
equivalent chains to form an open sheet parallel to
{100}. Above and below this sheet,the [PO,r]tetrahedra share three of their four vertices with the
octahedra to form a slab with formal composition
[Fe3.2(OH)2[PO.]rl' . Denoting oxygens associated
with the [PO+] tetrahedra as Op, the octahedral
component can be written [Fe3-2(OH)2(Op)o].The
slabs are bridged by the Fe(1)-O insular octahedra,
ideally written [Fe'.(Or)2(HrO)n], where Op are
59-t
17.6
c9.4
L2.6
100.5
99.3
52.0
I2.3
rr.9
38.q
?5-1
q0.9
rr,2
32.6
I0.1
1l"r
c1.2
2r.3
26.q
I1.7
42.1
23.9
63.3
?0.9
ll.q
!?.I
lc.8
53.5
q2.8
]q.s
22.3
q3.5
I5.q
tf.7
38.7
29.9
6 4 .q
33.2
88.q
28.r
58.5
[.c
3 9" 9
12.3
lr.7
36.6
77.I
61.0
28.6
t6.f
qt.q
l2.l
L2.?
28.1
2C . 5
Il.2
52.0
?9.C
17.3
2 1. \
23.6
68.!
tq.7
q[.!
Il.9
10s.1
100.1
50.7
t8.I
tr,9
38.1
24.2
a3.2
5.8
l0.l
2.I
7. a
a 7. 9
L7.1
19.5
8.0
92.1
2?.2
57.2
19.9
7. 6
5.6
32.9
q5.6
38.7
]f.6
25.1
37.6
IA.7
8.2
31.q
2 7. 1
59.5
10.0
88.1
21.7
51.5
2.9
30.q
3.2
25.0
lq.3
7q.5
60.7
?).2
r3.q
32.5
1.0
9 ,8
2 1. 2
18.8
tt.9
5t.6
21.2
8.2
26.q
15.0
Il.8
26.8
L7.2
r2.3
r2.2
12.3
17.q
12.3
ZL.3
r!.r
0.8
s.9
17.q
U.I
r2.3
6r.q
20.!
1 1. 7
t9.l
16.7
t9.r
48.7
16,0
74.2
8.t
22.3
45.3
i2.q
4.7
31.8
2t.7
23.1
2q.0
48.2
r0.l
2q,8
rr.8
27
"C
J6.8
6q,0
62.5
59.8
19.7
q5.9
tl.8
23.8
2\.2
r2.2
? 7. 5
12.I
I2.3
+ 2. 2
to.r
\1.1
15.5
85 . 3
?4.7
23.3
?r.)
q5.l
18.q
! l.q
q.2
?9.2
qr.8
3 7. 7
t.q
t0.9
lt.0
18.5
20.5
7?.?
t.l
?9.r
q.9
3f.5
18.5
61.f
65.0
55.8
!0.I
47.9
lq.1
26.0
20.9
1,8
2\.7
t.2
10.7
4q.5
38.0
q0.6
19.0
24.q
18.f
51.3
8r.q
16.8
15.q
q8.C
12.5
32.I
zL.t
36.5
29.1
32.7
64 . I
35.r
r2.3
2I.6
33,!
15.3
50.1
I3.8
\7 .7
11.3
52.q
12.q
12.C
I0.0
9.7
3q.C
22.6
)O.?
21.t
27.?
6C . 0
27.C
1.0
15.9
3a.2
II.q
q7,q
!.8
57.\
l. q
q7.l
3.1
4.7
8,6
l7 .7
r(,.0
I 5.!
\r.1
12.3
48.5
21.r
tr,O
I1,2
20.0
50.7
r2. I
28.0
rz.t
11.9
20.8
12.2
lZ.q
12.5
t0.l
l5. a
68.t
31.0
25-O
tz.q
cc.z
II.7
rZ.q
2\.7
27.3
6.6
63.5
27.\
Il.8
24.6
?2.2
c1.3
q7.8
35.2
74.8
9.3
5q.8
i0.7
20.0
ql.8
25.1
I0.8
u.q
12,0
2r.\
2,r.s
rt.l
!2.r
17.0
12.q
tZ.l
tt.,l
2\.2
12.q
2;.0
?r.a
zrt.,)
2L.7
2!.S
2t.4
17-rr
tl,6
t.r
10.8
t?.r
\!.1
!q.l
t!. q
rt.1
i.l
20.q
q!.3
12.7
Zi.l
u.l
?.J
16.6
9.q
1.5
6.I
2;.I
11.6
7l.t
27.\
r7.9
[.5
ql.o
t7.2
1.9
2\"1
2r.q
q.I
7q.q
28.7
20.9
13. l
2q.3
q9.9
62.3
q8.0
77.4
t0.9
65.0
1.9
23.6
19.6
2q.6
3.1
?.;
0.8
10.0
lo.2
l.q
qq.8
I;.!
10"2
l0.ll
lq.7
ll.2
lLr.s
l(.2
2J.j
lr.r
Jl, l
Jl.o
lt.i
17.l
the tetrahedral oxygens not associated with the
sheets.
Refinement of the crystal structure showed that
the Fe(1) site is only partly occupied. The interatomic distance averages indicate that this partial
occupancy results from the presence of some iron
in a higher valence state. We propose the distribut i o n F e ( 1 ) = 0 . 5 8 ( F e , M n ) ' ? .+ 0 . 2 8 F e s . + 0 . 1 . 4
Hole. Noting further that all water molecules are
ligands in the structure, the ideal end-member formula for whitmoreite is
""2*p"s*r(OH)e(H:O)r
Fe(l) site is partly
[PO+lz. In real crystals, the
replaced by Mn2* and Fe3*, the latter resulting in
disordered vacancies.
Interatomic Distqnces
Errors in interatomic distances are estimated to
be I 0.03 A for Me-O bonds and I 0.04 A for
O-O' edges. Polyhedral interatomic distances and
WHITMOREITE, A NEW SPECIES
their averages are listed in Table 4. We note that
the Fe(1)-O average,2.'1.4
A, is close to the 2.13 A
value calculated for (Fe2*e31Mn2',o.erFet*o
zs)-O using
the ionic radii from the tables of Shannon and
Prewitt (1969). As expected, the 2.66 A distance
for the shared edge, O(1)-O(1)t, is the shortest
for the Fe3*-O octahedron.
Hydrogen Bonds
905
Tlnrp 4. Whitmoreite. Polyhedral Interatomic Distancest
Fe (1)
2 Fe(r)-o(3)r
n -ow(2)
2
n -ow(l)
2
average
2
2
2
2
o(3) 1-ow(2) lar
0h111)-OVir2)
oi:'1i-66i1iiii
o(3)a-ow(2)
Fe(2)
z.os.E
2,11
2.26
2.r4
2.85
2
qq
3.02
3.05
3.L2
3. 2 0
Fe(z) -o(+)
n
-oH'
-oH
"
"
"
- o( 2 )
- o ( 1 )li .
- o ( 1 )1 1
"
average
o(r)i -o11;ii
-oHl
oH
o(2)1 -o(ri)
0 (l+) -oHt .
oH ,,-o(2)i
o (1)i--0 (?) '
o(r)'-oH]
oH - -o(4)
o(1)l -o(4) .
0(I):-.-o(2)'
o(I)::-oHi
o (I) "-or
average
1.96
1.99
2.0I
2.o5
2.0s
2.r5
2.0+
2.66*
2.76
2.78
2.79
2.88
2.88
2.89
2.94
2.s6
2.e8
3.O2
3.o7
The (OH)-, OW(1), and OW(2) molecules are 2 o ( 3 ) r - o w ( r. ). .
2 o!,t(z)-otll(r)aal
potential donors of hydrogen bonds. Since the
? n?
average
Fe(1)-O octahedron is insular with respect to other
octahedra, it has sufficient geometrical freedom to
admit hydrogen bonds.
1 P-o(1)
1 n-o(3)
I.s4
We propose the hydrogen bonds summarized in
I il-o(z)
1,s6
I "-o(4)
1.61
Table 4. The corresponding angles are O(3 )2.88
average
r.56
O w ( 1) - O ( 2 ) , 1 0 O o , a n d O W ( 2 ) ' - O W ( 2 ) - O ( 4 ) ,
Hydrogen
Bonds
2. 5 0
I o(r) -o(3)
93'. The network of OW. . . O bonds connect the
1 o(2) -0(3)
2. 5 0
Fe(1) (Op)p(HrO)a octahedron to the octahedral r o ( 1 ) - o ( 2 )
2 ql
oli(2) ..,or\r(2)t 3.03
I o(1) -o(4)
2.54
0w(2) ...o(4)
2.?2
slabs and are cut by the {100} plane. In this model,
I o(3) -0(4)
2.6r
o H l r - .. , . o ( 2 )
2.76
1 o (2) -0 (q)
2.62
0 w( r ) ' . . . o ( 3 )
2.8e
OW(2) both donates and receives bonds; other
0w(1) ...o(2)
2.er
average
2.55
possible geometries result either in very long distances-OW(2)t. . . O(3), 3.69 A-or
unreason- *Sha"ed. edge between Fe3* atoms.
a b l e a n g l e s - O ( 3 ) - O W ( 2 ) - O ( 4 ) , 5 2 ' . A c c o r d i n g ti =
*, ),/2-y, J./2+2, ii = -x, 1,/2+y, V2-2, iii = -x, -y,
-z referred to coordinates in Tab1e 2.
to this model, O(1) receives no hydrogen bonds;
O(3) and O(4) each receivesone bond; and O(2)
receives two bonds. This is consistent with the elec- Only O( 1) is oversaturatedsince it bonds to two
trostatic valence balance of cations about anions. Fe3.cationsand one P5. cation.
Acknowledgments
We appreciate donation of specimens by Mr. W. L.
Roberts of Rapid City, South Dakota, and Mr. F. F. Fogg
of Penacook, New Hampshire. Construction of the crystal
drawings was undertakenby Mr. D. H. Lund.
This study was supported by the NSF GA-40543 grant
and a Sloan Foundation Grant-in-Aid BR-1489 awarded
to P.B.M.
Ftc. 2. Polyhedral diagram of the whitmoreite crystal
structure down the z*-axis. The Fe'n-O octahedral sheet is
stippled, and the linking [PO.] tetrahedra above and below
the sheet are unshaded.The Fe(l)-O octahedron between
the sheetsis omitted.
References
BusrNc, W. A., K. O. MennN, AND H. A. Lrvv (1962)
Onrrs, a Fortran crystallographicleast-squaresprogram.
U.S. Not. Tech. Infnrm.,Seru. Onxr-rrvr-305.
Cnourn, D. T., eNo J. B. MINN (1968) X-ray scattering
factors computed from numerical Hartree-Fock wavefunctions. Acta. Crystallogr. L24, 321-324.
LARSEN,E. S., lNo H. Brr.r'reN (1934) The microscopic
determination of the nonopaque minerals. 2nd ed. U.S.
G e o l .S n u . B u l l . 8 4 E , 3 1 .
Moons, P. B. (1973) Pegmatite phosphates: mineralogy
and crystal chemistry. Mineral. Rec. 4, 103-130.
SHexwoN, R. D., eNo C. T. Pnnwlrr (1969) Effective
ionic radii in oxides and fluorides. Acta Crystallogr.
825, 925-946.
Manuscript receiued, April 4, 1974; accepted
lor publication, May 16, 1974.