American Mineralogist, Volume 63, pages 180-185, 1978
The crystal structureof paramelaconite,CunOs
M . O ' K r n r r E l A N DJ . - O . B o v l N
Inorganic Chemistry 2, Chemical Centre
P. O. Box 740, S-220 07 Lund, Sweden
Abstract
The structureof paramelaconite,
idealcompositionCuoOr,has beensolvedutilizingtl3
i n d e p e n d e rnet f l e c t i o nR
s , = 0 . 0 3 5T. h e s p a c e g r o uips I 4 r / a m d ; a : 5 . 8 3 7 , c : 9 . 9 3 2A . T h e
structurecontainsinterpenetrating
rods of Cu+-O (Cu* forming two colinearbondswith
oxygen)andCu'?+-O
(Cu2+formingfour bondsto oxygenatomsat thecornersofa rectangle).
The structureis simplyrelatedto thoseof cupriteand tenorite.
Introduction
Paramelaconite
is an oxideof copperintermediate
betweenCurO and CuO. It was first describedby
Koenig (1891),and more completelyby Frondel
(1941). Frondel's analysisgave the composition
CuOo,r.. He determined
the spacegroupof the crystal to be I4r/amd but did not resolvethe structure.
Authenticspecimens
are rare.2However,of the two
magnificentexamples(thoseexaminedby Frondel)
from the CopperQueenmine,Bisbee,
Arizona,oneis
in the Smithsonian
Institutionand onein the American Museumof Natural History. A fragmentfrom
the Smithsonian Institution specimen, #112878
(shownon the left in Fig. I of Frondel'spaper),was
kindly madeavailableto us by J. S. White,Associate
Curator.
Experimental
A powderpatternof a crushedfragmentwastaken
with a Guinier-Hiiggfocussingcamera,with KCI (a
: 6.2929A) as an internalstandard.This revealed
the presenceof some tenoritein addition to lines
ascribedto paramelaconite.
The paramelaconite
lines
couldbe indexedwith a tetragonalcellwith q : 5.837
and c : 9.932A (Table l). We did not observethe
ll0 reflection(not allowed in l4r/qmd) with d :
4.027A, reportedby Frondel (l9al); it is possible
I Permanent address: Chemistry Department,
Arizona State
University,Tempe, Arizona 85281
2 We have examined a number of samples purported
to be paramelaconite, all of which proved to be aggregates of cuprite and
tenorite. However specimens have been reported from Algomah
mine, Ontonagon County, Michigan by Williams (1962).
00
0003-004x/78l0t02-0180s02
that thisis a transcription
errorfor d:5.027 closeto
for l0l.
d : 5.032A calculated
The chip selectedfor structureanalysiswas an
irregular tetrahedronbounded approximatelyby
(100),(010),(001),and (ll3), and measuring
0.25X
Data
0.27 X 0.17mm alonga, b and c respectively.
werecollectedusingan automaticfour-circlediffractometer, CAD4 using graphite-monochromatized
A) and a take-offangle
MoKa radiation(I : 0.70930
of 6o. The os-20scantechniquewasusedwith Aco:
l.lo + l.0"tand.A minimumnet countof 3000for
each reflectionwas attainedwithin the maximum
measuringtime of 5 min. One octant of reciprocal
space(includingdependent
reflections
hkl, khl) outto
After every40 measurements
0 : 35" wasexamined.
werechecked.For all threestandards
threestandards
during the courseof the experimentR(: )l1o I ^l /> I ) < 0.008(1- is the meanof all observations),
lessthanthree
so no scalingwasnecessary.
Intensities
from countingstatisstandarddeviations(estimated
tics) were rejectedas unobserved.The reflections
werecorrectedfor polarisationand absorption.The
rangeof transmission
factorswas0.16-0.24(1t: 259
').
The absorptioncorrectionwas checkedby
cm
comparingthe deviation betweendependentreflections (hkl and khl) which fell from 25 percentbefore
correctionfor absorptionto lessthan 10percentafter
wereusedin
reflections
correction.ll3 independent
the subsequent
refinementof the structure.The unitfrom a leastsquares
weredetermined
cell dimensions
rangingfrom 6.4oto
refinementof twentyd-values,
25", collectedfrom the singlecrystalon the automaticdiffractometer
usingMoKa radiation.Crystallographicdata are given in Table 2.
180
O'KEEFFE
AND
l8l
PARAMELACONITE
BOVIN
Table l. Powder data for a mixture of paramelaconite and
tenorite
Table 2. Crystallographic data
Ce11 volune:
1 4r.' / a n d (- n o l 4 1 l
a = s.837(1) A
c = 9.932(2) A
338 A3
Ce11 content:
4 [ C u4 ,J O - ]
Space group:
Present
t/lt
Frondel
work
d(obs)
I
,llcaLc)'*'
h
3.1'74
101
110
112
2.912
2.880
200
103
5.014
',r
51
k
I
10
3.
20
2.929
12
2.757
51
2.52A
2.525
211
?a
54
2.508
2.475
2.516
2.443
202
004
59
2'7
?1
2.328
2 - 313
2.057
2.064
2 0
14
s
31
2 .04'l
r.900
1.885
2.050
1. 9 0 9
'I
. B9r
't3
3'7
22
f00
1 .869
1.112
1.542
1.587
34
95
10
1.508
1. 4 5 5
1.450
1. 4 5 9
1. : 1 5 4
92
1'7
36
1.436
1.419
1.409
39
1'7
24
1.3'77
1.305
1.267
85
7A
22
1.259
1,255
1. 2 3 8
'
not
**
^'"
t/It
d(obs)
w
vs
w
Tenorite"
't
n
Fornula
2, BBB
12
2 . ' 75 1
49
100
2.530
2 -523
04
w
,
u ( M o , ( c)
2. 3 1 2
2.050
*
Koenig (1891)
**
FrondeL (1941)
t -t)14
400
32 3
1. 4 4 9
20
1- 4 3 0
6
422
4O 4
008
1.254
1.241
indered aith
302.18
* = 5.83 s cm "
nD **= 6.04 e cm
=5.93qcmD
T.
r
259 cn-
25oC:
01
.440
in
weight:
Density,
2.490
2.464
25
B
r.866
1. 7 1 4
12
1.418
1.410
19
'7
1.375
1.304
'|
.265
6
Cmittee
ce11:
Unit
d
96
30
allooed
Joint
f
(194'l)
isotropic temperature factors and a scale factor convergedtoR:0.06.
On the basis of chemical analysis and measured
density, Frondel (1941) proposed a unit-coll content
of Cu,.Orn; accordingly,the possibility of partial occupancy by oxygen of positions 4a, 4b, and 8e was
investigated. Least-squares refinement led to the 4b
sitesbeing empty and the 8e and 4b sitescompletely
occupied, so that unit-cell content is Cu'.Orz (i.e.
CuoO.). The difference between this formula and that
determined by. analysis must surely be due to the
presence of admixed CuO in analyzed samples. The
calculated density (Table 2) is bracketed by two experimental values.
A final refinementwas carried out with anisotropic
thermal vibration factors for the copper atoms, and
scatteringfactors for Cu'+, Cu+ and O- were taken
from the International Tablesfor X-ray Crystallography (vol. IV, 1974). The secondary extinction coemcient (Coppensand Hamilton, 1970)was also refined.
T h e f u n c t i o n m i n i m i s e dw a s > l r , ( l F o l - l F " l ) ' w i t t t
w e i g h t s w - L : 6 ' ( l r . l ) + ( 0 . 0 0 4 . 1 F o 1 f I. n t h e l a s t
7
s
w
1. 2 5 1
1. 2 3 3
14 -,tanvl
I
Stqndards, 5-0661
of Pouder Diffraction
the tetragonal unit eeLL: a=5.837 dnd c=9.932 A
Solutionand refinementof the structure
Systematicabsencesconfirmed the spacegroup
Pattersonsynthesis
led
I4r/amd.A three-dimensional
directlyto placingcopper atomsin 8c and 8d and
oxygenin 4a and 8e: 0 l/4 z etc. wilh z : 0.12. A
preliminaryfull-matrixleast-squares
with
refinement
Table 3. Atom coordinates and thermal vibration parameters (B,j X lS)*
B(A2)
Cu(1)
Cu(z)
0(1)
0(2)
8c
8d
8e
4a
Estimated
foLloued
by
tenpe"atu"e
0
0
0
0
00
0
r/4
r/4
standard
the
r/2
0.1173(9)
3/8
erpops
Wykoff
facton
is
in
notation
erp(-gl.
Btt
Bss
'22
6 6( 6 )
qqrct
Btz
z 1( z )
e3(6)
38(s)
o
Bts
o
3(1)
Bzs
-23(4)
r(3)
0.8(2)
0.7(3)
parentheses
refer
for
the
equipotnt
h2 -
g*
u'
-
g,
to
the
of
Lt
Last
digit,
14../and.
-
,i,
The atoms designated
The forn of
hk - 2B1s hL -
the
anisotropie
zgzs kL).
az'e
182
O'KEEFFE AND BOVIN PARAMELACONITE
cycle all atom parameterschangedby lessthan 0.02
standard deviations. The extinction coefficient was
4.2(6).10' and the final agreementindicesR, (: [)w;
(lF.l - lF,l)"/2r,lFol"l'''):0.039,
R : 0.035ands
= ([)w, (lF,l - lF"l)'/(m- n))''' = 3.9.Thepositional and thermal parametersare given in Table 3,
and observed and calculated structure amplitudes
compared in Table 4. Distancesand bond anglesare
presentedin Table 5.
Discussionof the structure
The chemical formula of paramelaconite is
Cu+rCu!+Or.It is clear from the interatomic distances
and angles (Table 5) that Cu(l) is cuprous copper
Table 4. Observed and calculated structure amplitudes
h
?0
40
60
2?
42
62
44
64
84
66
DE
2E
18
54
34
14
E3
3?
1?
30
10
60
71
31
11
02
t,?
E2
t3
66
35
23
63
7?
32
?'l
61
30
10
00
20
t0
E2
42
22
E1
64
44
04
66
46
26
06
16
56
E3
k
tFol
0
0
n
0
0
0
n
0
0
0
0
2
2
2
z
2
z
?
)
2
)
3
3
3
1
3
3
I
I
4
4
4
4
4
4
4
l.
4
4
4
4
4
4
5
5
5
11 6. 1 3
592.56
4A,?4
5?5,07
59.0s
?71,56
122,34
33.4E
?02,77
1 8 3, 3 4
249.25
?1,84
25.?o
16.4E
24.78
?2,83
18.51
16.16
14.94
23.59
3 0 ,E 2
323,?3
14,80
15.35
47,23
730.40
46?.95
19 t . 6 2
27,15
2rtr,79
16.6E
3E.02
2?.?3
2?,39
34rE9
37.76
26.09
3 ?, 4 7
41.0E
6 2 6, 4 4
10 5 . 5 0
167r66
24,3?
56,0E
653.12
J4 4 . 0 1
26.?6
2 9 1. 3 E
395,5?
211.95
29'4?
324tt0
? 8 .5 0
?0.79
2 1, 5 4 .
1 8. 4 2
tFcl
14E.55
6 0 7, 7 ?
46,?3
552.1E
64,93
2 74 , 6 5
414,66
34.3E
19 9 . 5 1
t 66.86
244,6E
2 5 .E 0
24,55
16.13
2 4r ? 6
26,54
23.55
16.32
26'15
25.30
33,24
33?,70
13.05
53.09
47,L4
7?6,94
465,t9
201.37
27,8E
252,63
1?.38
34,95
2E,96
? 0 .E 0
34.96
36.66
2 E .1 6
3 ' l. 0 7
42,35
6 0 1. ? E
10 u . 0 7
1 7 7, ? o
?6.7E
56.02
659.19
14 4 . 0 E
3 0 .2 0
293,1E
107,77
2 0 E .19
3 0 .1 9
3 2 7, 0 8
3 7, 3 9
2 3 ,5 8
?2.44
16.34
h
k
4t5
215
606
116
0?6
646
?46
356
2E6
1E7
14?
347
54?
5?7
217
017
.307
507
60E
70E
004
31E
6?E
228
648
44E
24E
04E
08E
169
t49
039
?19
6
0
2
0
3
3
4
6
4
2
6
I
3
2
5
2
6
1
2
1
4
0
2
0
0
0
2
2
4
4
5
?
4
3
3
0
2
1
1
0
2
0
2
0
5
0
1
0
tFol
10
10
10
10
10
11
11
11
11
11
1?
12
12
12
12
13
13
13
13
13
14
14
t5
15
13 . 7 9
33.07
282,?9
30.14
569.93
2 2 0 .O 5
3E8.82
21.66
176.27
2 6. 8 0
35.59
2 t ,, 5 7
30.52
1 7, O ' l
22,76
14,52
23,92
35.46
3 2 .t 9
5?.99
560.98
14.6E
205,88
376.99
2 5 .! 3
304.87
t7 ,21
401.63
t 90.40
19.2E
22.69
1E . 4 6
16.50
22E.01
363.82
' t 7, 5 6
182,49
?E4,06
t4,27
40.59
? ' 1, E 2
23.99
t4,ZZ
?19,14
2 7. 3 2
265.12
305.79
18 7 . 9 6
23,23
25,16
23.49
1E . 3 0
20.09
??1,76
?21,7E
2 ' lt ? l
3E.35
tFct
12,76
?2,e7
2E3.45
31,79
5 4 3 .E 0
???,37
3 7 7, 7 0
13.35
rE1.67
29.0E
36.45
2 2, ' l ' l
33,44
I 5.E4
15,74
43.6E
2 2 .0 6
36,12
29.4E
52,50
565,72
12.E5
2 0 9 .13
360.29
24,47
297,37
3 7 . ' l1
3EE.5E
1 9 7, ' l E
16,44
Z5r1E
?6,1?
1?,49
2?0.23
55E.70
24,19
18 1, 1 1
274,56
3a,?5
4 1, 6 1
14.61
27.86
3 1. 6 !
219.31
29,59
277,90
3 0 1. ? 5
1?E,94
?7,52
?6.17
?E,49
22,61
16.9E
23E.00
? 3 7 .E 3
23,92
3E.6!
r83
O'KEEFFE AND BOVIN, PARAMELACONITE
T a b l e 5 . l n t e r a t o m i c d i s t a n c e s( A ) a n d a n g l e s( ' )
Angles
Distances
The Cu'-oxygen rod.
Cu(1) - 0(1)
o(1) - 0(1)
1 . 8 6 7( 6 )
(2x)
73s(r1)
0(1)
cu(1)
c u (t )
0 (] t
-
0(1)
Cu(1)
180.0
102.8(4)
The cu2*-oxygen rod.
cu(2) - 0(2)
cu(2) - 0(1)
0(r) - 0(2)
0(1) - 0(2)
(2xl
(2x)
(2x)
(2x)
r.e16(1)
1.e66(6)
2.sse(s)
2.920(1)
0(I) - cu(2) - 0(11
o(2)-cu(2)-0(21
0(1) - cu(2) - 0(2)
0(1) - cu(2) - 0(2)
180.0
r80.0
e7.s(2)
82.s(z)
1.867(6)
1.966(6)
2.919(1)
3 . 2 2 e( r )
Cu(1)-0(1)-Cu(1)
cu(r)-0(1)-cu(2)
Cu[2)-0(1)-Cu(2)
r02.8(4)
1.916(1)
2.e1e(1)
3 . 2 2 9( r )
Cu(2)-0(2)-cu(2)
cu(2)-o(z)-Cu(z)
Cu(2)-0(2)-cu(21
ee.2(1)
1r4.8(1)
ee.2(1)
The 0(1) - Cu tetrahedron.
0(I) - cu(1)
o(1) - cu(2)
cu(1) - cu(2)
Cu(1)- Cu(2)
( 2x)
(2x)
(2x)
(2x)
114.7(1)
es.8i4)
The O(2) - Cu tetrahedron.
0(2) - cu(2)
Cu(2)- cu(2)
Cu(2)- Cu(2)
*Standard
(4x)
deoiations
are
gioen
in
paz'entheses
The CuoO, structure. Open circles are oxygen atoms and filled circles are copper atoms. See also Fig 3.
184
O'KEEFFE AND BOVIN' PARAMELACONITE
Fig 2. Stereo view down the a axis of the structure of paramelaconite, Cuoog
and Cu(2)is cupriccopper.ThusCu(1)hastwo O(l)
nearestneighborsforming colinearbondsof length
1.87A, as found in cuprite,CurO (in whichthe bond
lengthis l 85A). LikewiseCu(2),surrounded
by four
oxygenatomsin a plane(almostat the cornersof a
square),is clearly Cu'+-the bond lengths 11.92
A(2X), 1.97A(2x)l and anglesbeingvery closeto
thoseobservedin tenorite,CuO [bond lengths1.95
A(2X), 1.96A(2X), Asbrinkand Norrby, 19701.
In
fact, the structureof paramelaconite
is simply and
elegantlyrelatedto the structures
both of cupriteand
of tenorite.
The structureis illustratedin FisuresI and 2. It is
composed of two kinds of rods of atoms running
through the structure parallel to [00] and [010]. The
two kinds of rod are illustrated in Figure 3, and are
(a) zig-zag strings of O-Cu+-O-Cu*, and (b) strings
of Cu2+On rectanglesjoined by sharing opposite
edges.The packing of each kind of rod is as in the
body-centeredtetragonal cylinder packing shown in
Figure 4, which also has symmetry I4r/qmd (O'Keeffe
a n d A n d e r s s o n .1 9 7 7 ) .
3 We use the term rod in the general sense of a figure with a
s i n g u l a r a x i s b u t w i t h o u t s i n g u l a r p o i n t s o r p l a n e s( S h u b n i k o v a n d
Kopstik, 1974).
(bt
Fig 3. (a) The Cu*-O rod. Filled circles Cu(l), open circles
O ( l ) . T h e b r o k e n c i r c l e s a r e t h e 4 b p o s i t i o n s o f 1 4 , / a m d .( b ) T h e
C u 2 + - O r o d . F i l l e d c i r c l e sC u ( 2 ) , o p e n c i r c l e sO ( l ) , c i r c l e d c r o s s
o(2).
Fig 4. Body-centered tetragonal cylinder packing with symmetry 14,/amd.
O'KEEFFE AND BOVIN.' PARAMELACONITE
Table 6. The structuresof Cu,O, Cu.Or, and "CuO" (PdO)
referredto a commontetraeonalcell
equipoints
e/a
CurO*
C u0 0 ,
r fC u o ' f * *
I .414
I . 70 2
1,.?54
*
sAnnetvy Pnsn
**
Dith
structure
4a
4b
of
8c
8d
Cu
o
0
of
I4y/and
+
Cu
1+
Cu'
8e
Cu
7+
Cu-
1+
Cu-
PdA, sAnnetrA P4r/nne
O,z=I/8
O, a = 0.117
O, z = l/8
185
approximates
that of cubic
the copperarrangement
closepacking(it is exactlythat in the cuprite)and
oxygenis in the tetrahedralintersticesof that packwaysin which
represent
ing. The observed
structures
oxygencan be insertedso that Cu+ hastwo colinear
bonds and Cu2+forms four directedbonds to the
It is an intriguingtopological
cornersof a rectangle.
problemto determinewhetherother waysof doing
this are possible-wethink not. This descriptionallows us to understandthe magnitudeof the axial
(c/a : 1.702)as a comratio in paramelaconite
promisebetweenthat for tetrahedralbondsfrom oxygen(c/a : 2) and squarecoordinationfor Cu2+(c/a
Referenceto Figure 3(a) showsthat addition of
: \/z).
oxygenatomsat sitesshownby brokencircles(correAcknowledgments
spondingto the 4b positions)convertsa rod of Cu+
by theSwedish
NationalScience
ReThisworkwassupported
and oxygeninto a rod identicalto the rod of Cu2+
and oxygen.The structurewouldthenbe that ofPdO s e a r c hC o u n c i l .
or, with a smalltopologicaldistortion(Wells,1976),
References
that of CuO. Conversely,
removingthe O(2) atoms
of thecrystal
(in position4a) from the rods of Figure3(b) would Asbrink,S. and L. J. Norrby(1970)A refinement
s t r u c t u r e o f c o p p e r ( I l ) o x i d e w i t h a d i s c u s s i o no f s o m e e x convert them into the Cu+-oxygenrods Of Figure
c e p t i o n a l e s . d ' s A c t a C r y s t a l l o g r . ,8 2 6 , 8 - 1 5 .
3(a), and the resultingstructureis topologicallythe C o p p e n s , P . a n d W . C . H a m i l t o n ( 1 9 7 0 ) A n i s o t r o p i c e x t i n c t i o n
sameasthat of CurO [to makeit exactlythat of CurO
corrections in the Zachariasen approximation. Acta C rystallogr.,
A26, 7 1-83.
would requirechangingc/a from 1.70to f2 and
changing
thez parameter
of O(l) from 0.117to l/81. F r o n d e l , C . ( 1 9 4 1 ) P a r a m e l a c o n i t e a: t e t r a g o n a lo x i d e o f c o p p e r .
Am Mineral.. 26. 657-672.
Thus the paramelaconite
structurecan be described K o e n i g , G . A . ( 1 8 9 1 ) O n p a r a m e l a c o n i t ea, n d t h e a s s o c i a t e dm i n either as derivedfrom the CuO (PdO) structureby
erals. Proc Acad. Nat. Sci. Philadelphia,2S4.
orderedremovalof oxygenatomsor asderivedfrom O ' K e e f f e , M . a n d S . A n d e r s s o n ( 1 9 7 7 ) R o d p a c k i n g s a n d c r y s t a l
chemistry. Acta Ctystallogr., A33, 914-923.
the CurO structureby orderedinsertionof oxygen
Shubnikov, A V. and V. A. Kopstik (1974) Symmetry in Science
These
atoms.
relationships
aresummarized
in Table6
a n d A r t P l e n u m P r e s s ,N e w Y o r k .
by referringall three structuresto a common tet- T e s k e , C . L . a n d H . M i i l l e r - B u s c h b a u m( 1 9 7 0 ) Z u r K e n n t n i s v o n
ragonalcell.
SrCu,O,. Z Anorg. Allgem. Chem., 379, Il3-124.
The paramelaconite
structureis closelyrelatedto Wells, A. F. (1976) Structural Inorganic Chemistry,4th ed. Oxford
that of SrCurO, (Teske and Miiller-Buschbaum, U n i v e r s i t y P r e s s .
1970),whichhasthe sarnesymmetryand similarcell W i l l i a m s , S . A . ( 1 9 6 2 ) P a r a m e l a c o n i t ea n d a s s o c i a t e dm i n e r a l s
from the Algomah mine, Ontonagon County, Michigan. Am.
dimensions.
The Cu+-O rods areidenticalin the two
Mineral 47,778-9.
compounds,and Sr replacesthe O(2) of paramelaconite.
An alternativeand complementary
way of describManuscript receiued, March 15, 1977; accepted
ing the structures
of the copperoxidesis to notethat
for publication, July 25, 1977.