Canadian Mineralogist
Vol. 17, pp.87-92 (1979)

A !,IEW MINERAL FROM TSUMEB'PROSPERITE,' HGAZNT(ASO-r):r(OH),soiJTH WEST AFRTCA (NAMIBIA)ROBERT I. GAIT rNo B' DARKO STURMAN
Departmentol MineralogXand Geology, Royal,O-ntario,Maseum'
100 Queen'sPark, Toronto, Ontario MsS 2C6PETE J. DUNN
Departmentof Minerat sciences,National Mus-eumol Natural History, smithsonian
D.C. 20560, US.A.
VI/ashington,

ABSTRACTProsperite occurs a$ radiating groups of white
to colorless, slender crystals up to 10 mm in lengtb
and 1 mm in diameler. The crystals have a brilliant
vitreous to silky lustre and are found in cavities
in partly altered massive chalcocite from the mine
at Tsumeb. South West Africa (Namibia). They
are monoclinic, space grot$ C2/c- or Cc with a
19.252(4\,b 7.737(2), c 9.765(2\A^,p r04"32(1)t,8. The strongest X-ray powder- diffracZ tion lines are: 3.87(5)(020), 3.78(7) (312'll2'),
3.37(6) (5 l0). 3.I I (8 ) (600), 2.ee2(, (1 r3), 2J88'(5X il3), 2.723(10) (222, 422, 421), and 2.614(6)'(513); A, l, (hkt). The crystals are elongate [001]'
and the forms in order of decreasing impodance{421}' {540},
are: {100}, {I01}, {110}, -{Ill},was{210}, {310}, {301} and {ll2}. No cleavage- 4.31
observed. Hardness = 4Yz (Moh$), Dor"g/cme, D""ro -- 4.40 g/cm3. Prosperite is biaxialp".iti*, no l.'146, nu 1.748, nn 1.768, 2Yow 34",
Y is parallel to b and Zltc zv.ok 36o, r))v,
27" in the acute angle between a and c. The
mineral does not fluoresce in either long- orradiation. Electron-micro'
short-wave ultraviolet
probe analyses gave CaO 13.02, CUO 1.35, ZnO
33,22, AszO"47.92 (H.rO = 4.0 wt. Vo,bv TGA),
total 99.51 wt. Vo, yielding the formula Hr.oa(OH) t.* or ideally(Znr.grCuo.or)
Car.os"r."nAs".nuOr.ru
The presence of OH was
HCaZn:(AsOa)r(OH).
indicated by infrared spectra, which also confirmed
arsenic as AsOo. The name honors Mr. Prosper
I. Williams, a noted mineral dealer from Toronto'tenses du clich6 de poudre (4,Institution'

l,

hkl\

sont:

3111(9)!l19)'
3.7s(7)(5r2,rr2)'
3.87(5)(020),
3.ili8i(600), 2.ee2(e)(1r3\' 2.788(5)(ll3)'
et 2'614(6)(513). Les
2.723(rO)(222,422,42r)
cristaux,' allong6s suivant t00ll' montrent lesformes suivantes,en ordre d'importanced6croiss a n i e {: r o o } , { I o 1 } , { 1 1 0 } ' { 1 1 1 } , { 4 2 1 } ' { 5 4 0 } ,6t6
lirot, iirot, {301} et {-ll2}. Aucungliylqe1'1
ofr"rve. Dnretl 4/z (Mohs): densitd4'31 (obs')'
4.40 (calc.)' La prosp6riteest biaxe positive, noI.746,ns 1.748,n, L.768,2V34" (obs')'36" (calc')'r))v, Y//b, ZlV - 27o dans l'angle aigu entre
a"et'c. ilulle fluorescencen'a 6t6 observ6edans
I'ultra-violet, ni aux longues,ni aux courtes longueurs d'onde. La microsondedonne CaO 13'02,
buO t.:S, ZnO 33.22, AuOs 47.92 .(H,zO-4'Ooh'
ear ATC), iotal 995LVo (poids), dlo!1.la formule
id6aleiir.orcur.on(2n1.e1Cue.6s)
11.eeAsr.rOr.ru(OH)..*;-iirj, HCuZnr(Asoe)z(OH). La orgrynce--d'hvdroxyle et de groupementsAsOa a 6t€ confirmde
par spectroscopieinfrarouge. Le min6ral est d6di6
I M.-P.otp". J. Williams, marchandde min6fauxbien connu de Toronto,
Clraduit Par la R6daction)
INtnoPucrtoN

The mine at Tsumeb, South West Africa(Namibia) is famous for its wealth of beautiful,rare and unusual mineral sPecies.Specimensof
Tsumeb minerals are the pride of mdny public
and private collections becauseof their brilliant
cryttilt and spectacular colors. Bartelke (1976)
notes that about 150 specieshave been identified; of these approximately 35 were first-deSorrtvernr
scribed from Tsu,meb.Stihnge (1964) described
general geological setting, the structure of
the -orebody-,
On trouve la prosp6rite en groupements radiaithi ore distribution, and its
longs
incolores,itheblancsres de cristaux a1long6s,
genesis and paragenesis.A review of Tsumebde 10 mm et d'un mm de diambtre. I*s cristaux,d'un 6clat brillant vifeux I soyeux, se trouvent
irineralogy is given in Wilson (1977)t relevant
dans des cavit6s dans la chalcocite massive parchapters-include an outline of the paragenetic
tiellement alt6r6e de la mine de Tsumeb, en
relaiionships (Keller 1977) and a review of
Namibie. Ils sont monocliniques, de gtoupe spati4l
pertaining to Tsumeb 'minerals
b'7.7,7(2),c 9.765@)L, the literaiurecc; a 19.252(4'),
Cii"(Weber1977).
""
Z = 8. Les huit raiesles plus in-9 l}4'32(l)"

87

88

THE CANADIAN MINEMLOGISTThe new mineral described here was broueht
to the Royal Ontario Museum for identifiiation by Prosper J. Williams in 1976. It is ahydroxyl-bearing hydrogen calcium zinc arsenate, ideally HCaZnz(AsOo)r(OH). We aredelighted to name it prosperite (pRdS-pdRAIT)
in honor of Mr. Williams, a noted rnineraldealer from Toronto, whose efforts have enriched the Tsumeb collections of manv museums, universities and private coliectors
throughout the world. The species and thename have received approval from the International Mineralogical Association Commission
on New Minerals and Mineral Names.
Type material is preserved at the Royal Ontario, Museum, Toronto (numbers M 313gg,
M 35389 and.M 35391), at the United States
National Museum of Natural History (Smithsonian Institution), Washington, D.i., U.S.A.
(numbers NMNH 143732 and 143733) and at
the British Museum (Natural History), London, England (number B.M. lg7g, lgt.

Subsequent to the completion of our investigation, Dr. Paul Keller informed us tlat
he had found prosperite during his study ofan arsenate assemblagefrom Tsumeb. He has
given us permission to describe the sequenceof deposition of the minerals in this specimen.
The secondary minerals have for.med on an
impure chalcocite in the following order: chalcocite, light brown adamite (0.3 mm thick),green cuprian adamite (0.3 mm thick), colorless radiating crystals of prosperite up to 4 mm
long, ahd stout prismatic prosperite crystals up
to 0.5 mm thick; these are followed bv several
other new minerals presently being describedby Dr. Keller, one of which is koritnigite(Keller et al. in press).
Until more specimens of prosperite become
available the paragenetic sequencemust remain
in doubt.
Pgystcer AND OprIcAL Pnopnnrrrs

Prosperite is white to colorless with a brilliant vitreous to silky lustre; it occurs as radiating groups of slender crystals. Dense aggregates. Prosperite is a secondary mineral occurring of crystals show a very faint blue tint. Prosin vugs in partly altered massive sulfide ore. perite has a white streak;its hardness is 4/z
A polished section of the altered sulfide matrix(Mohs scale); no cleavagewas detected.The(R.O.M. #M35392) indicatesthat rhe dominant density is 4.31(l) g/cmg,
measured on asulfide is chalcocite and that it enclosesminure Berman microbalanceon crystals weighing 10
blebs of silver containing about ZO - 25 wt. %to 15 mg; the calculateddensity is 4.40 g/cm}.
mercury (L. J. Cabri, p€rs. com.m.). part of The lower measured density
may reflect thethe chalcocite is altered to massive, waxy, fact that the material usedconsisted of agemerald-green conishalcite. Cuprite was also gregates of crystals
which probably had some
identified, closely associated with the chalco- spaces between them.
cite.
The mineral is biaxial positive with refracTwo types of vugs were distinguished. One tive indices n" 1.746(2), ne 1.748(2)and nytype is lined with druses of minute crystals of
1.768(2) for sodiumlight. The 22, (measured)
brilliant grass-greento olive-green conichalcite. is 34" :t 2o, comparing
favorably with a calThese vugs contain prosperite and pale, blue- culated value of 36'.
The dispersion of thegreen rosettes of bladed adamite crystals. Vugs optic
axes is r))y. The optical orientation isof the ,other type are lined with dult, pale as folfows: Y parallel
to b, Zltc is 27" in thegreen druses of cuprian austinite; these llso
acute angle between a and c. The calculated
contain prosperite and adamite crvstals. The Gladstone.-Dale constant (Mandarino
1976)
austinite contains approximately 4O mol /a of. for HCaZnz(AsO"),(OH)is 0.173, comparing
the conichalciteend-member.
favorably with K = 0.174 obtained from the_ ! ir not possible at present to make any calculated density and measured refractive indefinite statements regarding the formation or dices. The mineraldoes not fluoresce in either
genesisof prosperite becauseonly two specimens
Iong- or short-wave ultraviolet radiation.
are available for study; however, it does seemto be one of the last minerals to crvstallize.
Cnystellocnlpuy
The minerals associatedwith prosperite suggest
a similar sequenceto Keller,s typeII/4 09n).
MorphologyThe^most likely sequenceseemsto be: primary
sulfides-> conichalciteCaCu(AsO.) (OH) and
Prosperite occurs as radiating sprays of prisaustinite Ca(Zn,Cu) (AsOe)(OH) + adamite matic crystals up to 10 mm long and 1 mm
Znr(Aso4) (OH) + prosperiteHCaZnz(AsOe),- in diameter (Fig. l) and also as subparallel(oH).
aggregates in sheaf-like arrangements. Some
Assocraun MrNEnar,sPROSPERITE. A NEW

MINERAL

FROM TSUMEB

89

the face (301) that gave a poor signal ranging
from p - 6L - 64o, with the signal being
strongest at 64". This latter figure is closer
to (702), pcak : 64"25'. However, on theprecessionX-ray photographs, the (602) reflection is much stronger than (14.0.4), indicating that (301), pcarc: 6LoZy should be
assignedto this face.
The form {311} was recognizedonly as atiny face on one crystal and is not shown inthe drawing (Fig. 2). The crystalswere slightly
bent and twisted, and so the accuracy of the

Frc. l. Prosperite:the main crystal is 5 mm long.
of the larger acicular prisms are composed ofseveral smaller crystals in parallel orientation.
The crystals are elongate parallel to [001];
in order of decreasing importance, the forms
are: a t100), d {T0t}, m {110}, p {T11}, z{421}, n {54o), k {2r0}, I {310}, o {301} andx {112}. Figure 2 shows two views of a crystal
with these forms developed; some of these
forms may also be seenin the scanning electron
microscope photographs in Figure 3. Table 1
contains the interfacial angles for prosperite.
It was not possible to make a definite distinction between crystal classes2/ m and m fromthe observed data because the forms parallel
to c were not completely developed all around
any one crystal; the other forms were only
observed on singly-terminated crystals. Howevef. the evidence favors class 2/m.
It has been pointed out that the form {530}should be expected rather than {540h however, all the hkl faces observed on the crystals
have corresponding reflections on the zeroIevel Weissenbergtaken parallel to c. A weakreflection was noted for (10.8.0), equivalent
to (540), but none was observedfor (530) or(10.6.0). Another ambiguity arose concerning FIa. 2. Crystal drawings of prosperite.

90

THE CANADIAN MINERALOGISTTAELE2.
lbnoc'llnlc,

X-RAYPOI{DER
DIFFRACTIOTDATAFORPROSPERITE

C2/a ot ca

a . ' t 9 . 2 5 2 ( 4 )b, . 7 . 7 3(72 ) ,a . 9 . 7 6 5 ( 2 ) ABi. l 0 4 ' 3 2 ()l,ltkl

Frc. 3. Two SEM views of a prosperite
prosperite crystal.
crystal.
Bar represents0.05 mm.
measurementsin Table L was lower than generally obtained with the optical goniometer.
X-ray diflraction

dataSingle-crystalX-ray data were obtained from
Weissenbergand precessionmethods. The mineral is monoclinic, spac€ group C2/ c or Cc.
The refined cell dimensionswere obtained froma least-squares refinement using the X-ray
powder diffraction data and selectedknown indices from the precession photographs. The'arecell constants
a 19.252(4), b 7.737(2), c
9.765(2)4, B to4. 32(1)r. The cell volume is1408.1A'; Z = 8 formula units.
Prosperite gives a sharp, distinctive X-ray
powder diffraction pattern. Table Z shows theobserved data from two methods, Guinier-de
Wolff and Gandolfi (using a powder-ball mount),
compared with the calculated spacings fromthe refined cell parameters. The X-ray powder
TASLEI.

ATIGLETAELEFORPROSPERIIE

ibnocllnlc, a. "19,252(41,(21, a. 9.765(2)1,
u - 7,737
0. I 04"3A(
I ),
For0
a 100
n ll0
r 540
k 210
I 310
o 301
d lol
p lll
b 112
I 421
/ 3ll.

feasured
22"47'
27"43',
39"r6',
5202'-90.
-11"50'- 1.02,
4&.
-45"40'*Not shom ln Figure 2

90'
90.
il"-4.
15"81
52.18,
33"22'
72t{
60'20'

Calculated
90"@,90.00t433'
90"00'
27"25'
90"00,
39"42'
90.00'
51"14,
90"00190.00,
5t.21,-90.00,14"501-il.51'52121- 0"15,32.15'
43.01,
73.50t46"07.6.1.13.

d".l.l

200.
9.32
'I
l0* 7.14
Ill
5.98
310 4.U
002* 4.73
712* 4.r3
3rI
4.00
ozt
3.869
'lt2
3,779l'3rz 3.7tzl
02"t 3.5801
220 3.573f
511 3.417'
510* 3.358
22't 3.241
600' 3.t06
I13* 2.991
5ltr 2.960
313 2.914
l131 2.786
222 2.7261
4zz z.7z3l
421 2.7'17'513* 2.61t
7tI
2,590
130 2.555
l3r
2.4s81
512 2.M51
223 2.4a5J
r3r
2.4451
023 2.4431
2o4 z,Mt I
629' 2,422
0041 2.363
422 2.3541
6n
2.3501&2
2.3si
Ir4
2.3il1
3
r
4
2
.3101
'l3z
z.zso
713 2,244lt
62'1 2.2431
514 2.175
2U
2.1651
602 2.t601
531 2.'t361
623 z.nzl
513 2.976
glt
2.061
821 2.0431
712 2.031'
912 2.027
53t 2.009(0)l423 2.008(e)l
8zz t.eeel"
820 1.9961
333 1.995'
314 1.9771
714 1.9721
040 1.934
404 1.922
9 t 3 t . 9 tl
224 t.889 I!33 l,888(B)l
624 1.886 |731 i .BsrI

8n

821
115
5I5
242
441
440
il5
5t4
242
u2
425

r.s7sl

1.872(9)lr . 8 7 2" f 8I 1
1.s34
1.790 Ir,78t t1.786 tr.785(8),1.755
1.7281
1.7271
1.1261

Gulnler de
Iol ffd*u.A

6andolfi'114,6m(p@def bal lrDunt)

test

d*u.A

test

3

9.34
7.17

4

9.26
7.I1

tt

\

4.82
4.72
4.10
3,99
3.86(6)

4,69

tz
7

3.97
3.85(3)3.77(3)h3.78(0)3.57(1)tt

3.57(0)'I

3.42(l)3.36(5)3.25(0)3.ll (r)
2.992
2.959
2.9't9
2,788

\
6
'|

J.

JI(

5

J,'

3 .l 0 ( 8 )
2.991

I
o
'I
It

8

2.78
2.722

t0

6
I

2.611

5

2.N3

4

2.M

2,442

3

2.42

I

2.419
2.362
2.49
2.332
2,310
2.276

3
4
h

2.424
2.360

1

1

2.168

\

?

2.132

I

2.08
2.032

t[

\
h

2.006

t.970
't.931
1.920
1.907

,

1.975

1.81t93

1.878't.870
'I
.835

h

r

't

.835

h

1.784

2

"t.l$

I

I .754

k

r.756

,1

1.724

2

1.726

z

2.723

10

2.6'14
2.W4
2.550

\

,1

a.z5a

2.177
2.173
2 ,l 3 l
2.040
2.062
2.039
2.023
2.009

I

l!

t2

t

t.993

t

I
?

\

t.9t0
',1.889

Plus mny additional llnes to 0.77744
rlndered frcn precesslon photographs
CUK^radlatlon

PROSPERITE. A NEW

diffraction data were recorded using CuKa
radiation. The intensities were estimated visually.
The parallel and sub-parallel aggregation of
the crystals gives them an appearance suggestive of lamellar twinning. However, no evidence of twinning was found in the singlecrystal X-ray study or during the examinationof the crystals with the petrographic microscope and the universal stage.

9L

FROM TSUMEBMINERALOF PROSPERITEMICROPROBEANALYSIS
ELECTROIITABTE3.

Theoretical

Analytlcal

ut.
ca
13.02
Zno
33.22
cuo
1.35
AsZ05 47,92
H20r
4.0
Total ,r.5f

12.02
34.87

No. of Atoms
ca I.00
Zn 2.00

49.25
3.86

z.oo
;
Hao 1.00

Ut. %No. of Atonsca
1,09
l.9ll r ooZnCu
0 . 0 8 1" ' As
L95
H20 1.04
Total

r0o.oo*TGA

Cltnutcar, CovtrostttoN

Enplrlcal fomula, calculated on the basis of 9 oxygenatons:
Hr.
o 4 c u t , o 9 ( Z n9r .i ' c u o .o a ) r t . g g A " t s. s O zs. o ( 0 Ht), 0 4

Crystals of prosperite were analyzed using
an ARL-SEMQ electron microprobe with anoperating voltage of 15 kV and a beam current, measured with a beam-current monitor,of 0.15 g,A. The results were corrected forbackground, backscatter, fluorescence and absorption.
The standards used in the first series ofanalyses were: synthetic olivenite for Cu andAs, synthetic ZnO f.or Zn, fluorapatite for Ca,
P and F, and hornblende for Fe, Mg and Mn.
Of these elements, only Ca, Zn, Cu and As
are present in significant amounts. Fe is present
as a trace and P, F, Mg and Mn are either
absent or present only as traces. A microprobe
wavelength-dispersivescan at 20 kV indicatedthe absenceof any other elements with atomic
number above 9. Separate analysesusing otherstandards confirmed these analytical results.
Four crystals were analyzed using the above
methods and standards, with an average of 10
or more sarnple points on each crystal. Scans
were made at 1O1t intervals acrossthe crystals,
but no compositional zoning was detested. The
crystals were found to be very similar in composition, with only minor variation in the
Zn:Cu ratio. There is a sympathetic variation
betweenZn and Cu from sample point to sample
point. The Cu content varies as much as t
50% ol the amount shown in Table 3 (1.35
vttVo); this variation seems random and not
crystallographically controlled. The final electron microprobe analysis is given in Table 3
and was obtained using the following standards:
adamite f.or Zn and As, synthetic olivenite
for Cu, and hornblende for Ca.
The differential ther.mal analysis and thethermogravimetric 'measurements rilr'ere performed on a Mettler Thermoanalyzer using an
11 mg sample of the mineral. The sa.mplewascoarse-ground to between 200 and 100 meshin acetone and only the coarse material used
for the analyses. This was done to minimize
the loss of (OH), to be expected if the sample

Ideal fomula:ttcaZnr(Ason)t(0H)

Accuracy of data:t 3g of the munt shownfor Car zn and As
t50g of the mount 3hom for Cu

is too finely ground. The sample was pre-driedin a high vacuum. The reference substance
was a-ALOs, the crucibles were composed of
AlrOe, the heating rate was 8"C per minutein a dynamic nitrogen atmosphere up to
1000'C. The DTA and TGA curves for prosperite are shown in Figure 4. The prominent
endothermicpeak at 655'C is related to a 4.0
wt. % loss occurring between 469" atd 682"C
with the main loss between 641" and 665'C.
The infrared spectra indicate that this weightloss is due to (OH); the remaining H is ex'pressed as hydrogen in the chemical forrnula.
Additional endothermic peaks at 927" and965"C are related to fusion of the sample.
Infrared analyses were perforrned on two
samples by Mr. D. M. Fandll of CANMET,
Ottawa. One samplehad been heated to 680'C
in dry nitrogen and the other was the natural,
unheated material. The spectra of the mineral

Erothermlc

t
I

I

J

I

\ FustonEndolhermlc

TGADTA------

I
|
I

I
prosperite.
Frc. 4. DTA/TGA curvesfor

92

THE CANADIAN MINERALOGISTand the standard,synthetic As2O3,were recorded DTA and TGA studies, Drs. J. A. Mandarino
in the infrared in the double-beam mode using and F. J. Wicks for their critical reading ofa blank KBr disk for reference.All the spectra the manuscript, Mrs. Violet Anderson for thewere recorded on a Beckman IR-12 spectro- photomicrograph,Miss Hclen Driver for typing
photometerunder standardoperatingconditions thc manuscript, and Mrs. JosephineGalt forin the 0 - IOOVoT mode. The results of these typing the tables; we thank the Department
infrared analysesindicated that the weight loss of Photography and the Art Department forof 4.0 wt. 7a should be attributed to (OH) and their assistancein preparing the figures andthat the arsenic should be expressed in the drawings.Finally we thank ProsperJ. Williams
chemicalformula as AsOr.
for bringing this mineral to our attention andOn the basis of this information, the em- for donating one of the specimensto the minpirical formula calculatedfrom the final analy- eral collectionsof the Royal Ontario Museum.
sis may be given as Hr.orCar.os(Znr.nrCuo.oe)>,.rrAsr.ssOz.ou(OH)r.on
on the basis of 9 oxygen
RsnEnnNcss
atoms. The ideal formuls may be expressed
as HCaZn:(AsOo)'(OH).

Bentrxe,
W. (1976): Die Erzlagerstiitte vonTsumeb, Siidwestafrika und ihre Mineralien.
A ulschluss 27, 393-439.
CoNcl-usrox
Krrren, P. (1977): Paragenesis:assemblages,sequences, associations. /z Tsumeb. The World's
Prosperite seems to be unique, and bears no
Createst Mineral Locality. (W. E. Wilson, ed.).
chemical or structural analogies to other minMineral. Record 8(3), 38-47.
eral species, or to synthetic compounds. CrysHrss, H., Stisss, P., ScHNoRRER,G. &tals have been supplied to Dr. J. D. Grice
DUNN, P.J. (1979) : Koritnigit, Zn[HrOlHOAsO,l],of the National Museum of Natural Sciences.
ein neues Mineral aus Tsumeb, S0dwestMineral SciencesDivision, Ottawa for a strucafrika. Tschermaks Mineral. Pelrog. Mitt. 26
tura determination.
(in press).
MeNoenrNo, J. A. ( 1976): The Gladstone-Dalerelationship - Part I: Derivation of new conAcrNowr,sncEMBNTS
stants. Car,. Minerul. 14, 498-502.
S6Hxcr, P. G. (1964): The geology of the Tsumeb
The authors are most grateful to Mr. D. M.
mine. ftr The Ceology of some Ore Dqposits inFarrell of CANMET, Ottawa for perfonming
Southern Africa. lI. Deposits of some Minerals
the infrared analyses on prosperite. Dr. Louis
Outside the Witwatersrand Basin (S. H.
J. Cabri kindly identified the main opaque minHaughton, ed.), Spec. Publ, Geol. Soc. S. Alr.
erals in a polished section of the matrix ma- Wrnrn, D, (1977): Minerals: a review of theterial. We thank Dr. Paul Keller of the Uniliterature. ln Tsumeb. The World's Createst
versity of Stuttgart, Federal Republic of GerMineral Locality (W. E. Wilson, ed.). Mitreral.
many, for allowing us to use the description
R e c o r d8 ( 3 ) , l 0 l - 1 1 0 .
of his prosperite specimen.We also thank the WtLsoN, W. E., ed. (1977): Tsumeb. The World's
following people at the Royal Ontario Museum
Createst Mineral Locality. Mineral, RecordS, (3).

for their contributions: Mrs. Cynthia Peat for
doing most of the X-ray powder diffraction
patterns, Mr. R. A. Ra.mik for performing theReceived August 1978; revised manuscript uccepted
September 1978.