AmericanMineralogist,Yolume70,pages4ll4I3,
1985
.8H2O, a newmineralfrom Wales,U.K.
(Ce,La,Nd)z(COs)s
Lanthanite-(Ce),
Rrcunno E. Bnvns
Departmentof Geology,National Museumof Wales
Cardffi CFI 3NP, Wales,U.K.
Gnoncs Rownorn^lrr,r
Departmentof Geology,Uniuersityof Keele
Keele,ST5 sBG, England,U.K.
FnroeRrcr S. SrepHENs
Schoolof Chemistry,Macquarie Uniuersity
North Ryde, New South Wales2113,Australia
SrepnsNTurc@sBr fi.ro PerEnA. Wnrnus
Departmentof Chemistry,UniuersityCollege
PO Box 78, Cardif, CFI IXL, Wales,U.K.
Abstract
Lanthanite-(Ce)
occursas a secondary
mineralin oxidizedcopperore at the Britannia
Mine, Snowdoni4North Wales,U.K. It is found as colorlesstransparentplates{010}
coveredby radiatingtufts of malachiteand is associated
with brochantite,posnjakite
and chalcoalumite. The analytical formula, based on t7 oxygens, is
(Ce6.rrl-ao.rrNdo.rrSmo.o"Gdo.orYo.oohr.ouCz."rOg.ot'7.96H2O,
and the theoreticalformula
is (Ce,La,Nd)r(CO3)3.8H2Owith Ce > La,Nd. Orthorhombic, space goup Pbnb,
a:9.482(6), b : 16.938(ll),c : 8.965(3)A,Z:4, D(calc.):2.79 E/carrfor the idealformula
(Ce:La:Nd: 0.83:0.59:0.58),D (meas
.l : 2.76 g/cmt, V : 144043,a:brc:0.559E :1:0.5293.
Strongestlines in the X-ray powder diffraction pauern are ftlA (I) (hkl)l 8.47(100X020),
4.746(65)l2W),4.462(62NW2),3.255(73N202)
and 3.028(65\222\.The mineral is biaxial negative,a 1.532(2),
P 1.594(2),yl.6lQ2); orientationX:b, Y:c, Z:a;2V(measJ:60(2)0,
2V(calc.)=62",no dispersionobserved.The mineralis not fluorescent,
and has H:2.5, a
colorlessstreak, a vitreous luster and is sectile.In dilute mineral acids (HCl, HNO.), the
mineral reactswith effervescence
to yield a gel-likeprecipitateoflanthanide(Ill) hydroxides.
Introduction
Lanthanite, the lanthanum end-memberof the seriesof
minerals with the general stoichiometry (RE)r(CO3)3'
8HrO, was first describedby Berzelius(1825).Its general
composition was determinedby Blake (1853)and Genth
(1857).The presenceof other lanthanides("didymium") in
the material from Bethlehem,Pennsylvania,U.S.A., was
noted. It is a rare mineral species,but has been noted to
occur sparingly at a number of localities (Saebo,1961).
Lanthanite-(Nd)(Robertset al., 1980)was found recentlyin
a silty arenaceousclay at Curitiba, Paran6,Brazil; Nd and
La were the main rare earthspresent,togetherwith minor
Pr, Sm, Gd, Eu, Dy, Y and Ce.
r Presentaddress:ConservationDepartment,UMIST, PO
Box
88,Manchester,M60 lQD, England,U.K.
0003-o04x/85/030,4I 1$02.00
4ll
In the courseof our studieson the geologyand mineralogy of the Britannia Mine, North Wales,U.K., (National
Grid Ref. SH 615 547),we found clear platy crystals in
oxidized copper ore. This material proved to be the new
mineral lanthanite-(Ce),the cerium-predominantmember
of the lanthanitegroup, which is describedbelow.The mineral and its namehavebeenapproved,prior to publication,
by the Commissionon New Minerals and Mineral Names,
with the acIMA. Lanthanite-(Ce)is namedin ac'cordance
ceptedrare earth minerals nomenclature(Levinson,1966).
Type material (National Museum of Wales specimen
number NMW 84.6G.M1)has been depositedin the collection of the National Museum of Waks and is available
for further study. Other material has been depositedwith
the British Museum(Natural History), the SmithsonianInstitution and Museede Mineralogie,Paris.
4r2
BEVINS ET AL.: LANTHANITE-(Ce)
Occurrence and associations
Lanthanite-(Ce)was found in the secondlowest accessible level of the Britannia Mine. Well-crystallizedplates
(Fig. 1),up to 5 x 5 x 0.5 mm, occur on the walls and back
of the adit, and are coatedon {010} by spheresof acicular
radiating malachite. Associatedminerals are brochantite,
posnjakite and rarely chalcoalumite.This whole assemblage is sometimesfound coated with a glaze of ferric
oxyhydroxides.
Lanthanite-(Ce),as well as its asSociates,
is obviously of
secondaryorigin and has crystallizeddue to rare earthbearing groundwaters percolating through the old mine
workings. The rare earths may have been leached from
allanite which has beenidentifiedin the acid pyroclasticsof
the SnowdonVolcanic Group (G. Hendry, pers.comm.).In
the immediatemine area,high concentrationsof rare earth
elements are present in the rhyolitic intrusions of the
Snowdon Volcanic Group. Theseintrusions contain La in
the range 60-100 ppm, Ce 140-200ppm and Nd 70-120
ppm (T.K. Ball,pers.comm.).
Physical and optical properties
Lanthanite-(Ce)is colorless,transparentand platy {010}.
No other forms were observed,all of the platesso far seen
terminating with ragged edges.It has a white streak, a
Table 1. Analytical data for lanthanite{Ce)
Ce
1 7. 6 0
,"r03
20.61
12.31
taz03
14 . 4 4
Nd
12.67
Ndzo3
1 4. z 8
Sr203
2.50
Gd
1.33
Gd203
1.53
u.50
'ro3
o' l \
c0-
2 1. 0
coz
H-0
23.0
Hzo
2 r . 02 3 . 0b
Total
98.6
a
Rare-ea.ths
recalculated
earth weight percents are
el ectron
b
c
Alro
microprobe
c
Rare_
the average of
five
anal yses.
th" average of
The empirical
to oxides.
h
five
analyses'
formula based on t7 oxygens is
{ c t g .7 B L " o5.5 N d 50 5. s t oo. 9 c d oo.5 Y oo.q ) r z o. 6 c z9. 7
0 9 . 8 . 7. 9 6 H r o .
vitreousluster and is not fluorescent.The hardnessis about
2.5 and the plates are sectile. Cleavage {010} is welldeveloped.The mineral dissolvesin dilute mineral acids
(HCl, HNO3) with effervescence
to yield a gel-like precipitate of lanthanide(Ill) hydroxides.Density was determined
by flotation of hand-picked crystals; the value of 2.76
g/cm3 comparesfavorably with the calculateddensity of
2.79 glcm3basedon the theoreticalformula withZ : 4.
The mineral is biaxial negativewith measuredrefractive
indices a r.532(2),P t.594(2),y r.616(2\(,1:589 nm).
2ll(meas.)was 60(2)",the calculated value being 62". No
dispersionwas observed.The orientation is X : b, Y : c,
Z : a. The compatibility (1 - (Ke/K") : -0.010) is superior based on the Gladstone-Dale calculation. The
physicaland optical valuesare closeto thoseof Larsenand
Berman (1934)and Saebo(1961)for lanthanite,and those
of Robertset al. (1980)for lanthanite-(Nd).
Fig. 1. (upper) Scanning electron photomicrograph
of
lanthanite{Ce) encrusted with malachite and (lower) an annotated
sketch of the same area. Lan : lanthanite-(Ce) and MaI : malachite.
Chemical composition
Electron microprobe analyseswere carried out at the
University of Manchesterusing a Cameca(Camebax)instrument operating at 15 kV and with a specimencurrent
of 3.5 x l0-E A in the energydispersivemode.Analytical
graderare earth oxides(CerOr, LarO3, Nd2O3, SmrO.,
Gd2O3and YrO.) were usedas standardsand the X-ray
lines usedwereLa with correctionsmade for interferingLB
lines.CO, was determinedusing a TechniconCHN analyser and water of hydration analyseswere performedthermogravimetrically using a Stanton Redcroft TG 750
balance.Analytical data are pretemperature-programmed
sented in Table 1. The empirical formula based on 17
oxygen atoms is (Ceo.rrl-ao.rrNdo.rrSmo.onGdo.o,
Yooohr.ouCz.rrOr.o..7.96H2O.
The massdeflciencyin the
4r3
BEVINS ET AL: LANTHANITEICe\
Table 2. Unit cell data for lanthanitegroup minerals
,o.
a (A)
9 .4 8 2( 5)
9 . 5 0 t r( 4 )
9 . 4 7 6( 4 )
r6.938(il)
1 6 . 9 4 3( 6 )
16 940(8)
8.965(3)
8 . 9 3 7( 5 )
8 . 9 4 2( 4 )
_o.
b (A)
o.
c (A)
a ( m e a s). ( g / c n 3 )
2.16
a ( c a l c . )( s / c m l )
2.79
2.8r
z\
qn-.A
l.
^r^"^
2.82
4
Pbnb
Dhhh
!=!=
Lanthanite-(Ce);
Lanthanite;
1
2.78
4
this
study,
Bastnes, Sweden; Dal Negro *
Lanthanite-(Nd);
P b nb
Paran5, Brazil;
(1977).
al.
(1980).
Roberrs et al.
analyticalresultsmay be attributed to sampledeterioration
during preparation and probe analysis.This was also observedduring microprobe analysesof lanthanite-(Nd),but
in that case sample deterioration was much more pronounced (Ansell et al., 19761.The ideal formula for
(Ce,La,Nd)r(CO3)3.8H2O with
lanthanite-(Ce) is
Ce > La,Nd, and the Ce:La:Nd ratio usedto calculatethe
densityof the mineralis 0.83:0.59:0.58.
X-ray data
precession
studiesof orientedcrystalsindiSingle-crystal
cated orthorhombic symmetry,and measuredunit cell parameters are a : 9.4846), b : 16.938(11),
c : 8.965(3)A.
Quoted errors are derived from multiple measurementsof
precessionphotographicdata, using MoKa radiation. V :
l44OAtandZ:4; a:b:c: 0.5598:1
:O.5293.
Systematic
absencesin the reflexion record are Okl (k:2n + l), hk0
(k : 2n + 1) and h0l (h + I : 2n * 1) which uniquely
define the space group Pbnb (a non-standard setting of
spacegroup Pccn).These data are entirely consistentwith
those reported by Dal Negro et al. (1977) on a natural
sample of lanthanite (lanthanite-(La)) from Bastnds,
Sweden,and by Roberts et al. (1980)on lanthanite-(Nd)
from Curitiba, Paran6, Brazil. Single-crystaldata for all
three minerals are compared in Table 2. The strongest
X-ray lines in the powder diflraction pattern, listed in
Table 3, are ldA g](hkl)l 8.47(100x020),4.746(6s){2o0),
4.462(62)(002),3.2ss(73){202)and 3.o28(65N222).The
powder data are virtually identical to those tabulated by
Robertset al. (1980)for lanthanite-(Nd).Obviously,quantitative chemicalanalysesare necessaryfor a reliable distinction betweenmembersof the lanthanitegroup.
Table 3. X-ray powderdata for lanthanite-(Ce)
Acknowledgments
DepartMackenzie
andZussman,
We wishto thankProfessors
Universityfor the useof electron
mentof Geology,Manchester
microprobefacilities,and D. Plant for preparingthe rare earth
r/r ^
o
d A obs.
o
dAcalc.
hkl
r00
8. lr7
8.\69
020
\.746
\.7\1
200
62
\ \62
4.483
002
)5
4 211
\ .235
040
40
L
1)a
\.137
38
3.9\3
3.962
022
9
3.814
3.829
04r
3.257
202
73
220
8
3.158
3.158
2\0
65
l. 028
3.040
222
15
3 .0 0 0
1.006
151
l0
2.8\5
2.850
101
9
2 . 70 9
r8
2.691
2.693
061
35
2.571
2.582
242
5
7
150
qa7
340
D e $ y e - S c h e r r e rc a m e r a ( N i - f i l
o - A1203 added as internal
indexed wi11 6 = !.482,
intensities
tered CuKq
standard.
radiation)
The pattern
b = t6.938, c = 8.955i
were estimated with
a densitometer.
wi th
is
standards.A. C. Roberts considerablyimproved the manuscript
of Mike Lambert
with a thorough review.The technicalassistance
(NMW) is alsoappreciated.
References
Ansell,H. G., Pringle, G. J. and Roberts,A. C. (1976)A hydrated
neodymium-lanthanum carbonate from Curitiba, Paran6,
Brazil. GeologicalSurveyof Canada,Paper 76-lB, 353-355.
Berzelius,J. J. (1825) Kohlensaurescereroxydul.Zeitschrift fiir
Mineralogie,2, 209.
Blake,W. P. (1853)On the occurrenceof crystallizedcarbonateof
lanthanum.AmericanJournal of Science,16,228-230.
Dal Negro, A., Rossi,G. and,Tazzoli,V. (1977)The crystal structure of lanthanite.AmericanMineralogist,62, 142-146.
Genth, F. A. (1857) Lanthanite. American Journal of Science,
Series2,23,42926.
Larsen, E. S. and Berman, H. (1934)The microscopic deterrnination of the nonopaqueminerals.Bulletin of the United States
GeologicalSurvey,848,164.
Levinson, A. A. (1966)A systemof nomenclaturefor rare-earth
minerals.AmericanMineralogist,51, 152-158.
Roberts,A. C., Chao, G. Y. and Cesbron,F. (1980)Lanthanite(Nd), a new mineral from Curitiba, Paranl, Brazil. Geological
Surveyof Canada"Paper 8o-lc, l4l-142.
Saebs,P. C. (1961)On lanthanite in Norway. Norsk Geologisk
Tidsskrift,4t, 3ll-317.
and
Manuscriptreceioed,
March 13, 1984:
accepted
for publication,OctoberI 2, 1984.