American Mineralogist, Volume61, pages l00l-1004, 1976
Strontianitecompositionandphysicalproperties
L. HeNsLsv-DUNN'
ANDMARGAneT
J. AlexennenSpeeR
Departmentof GeologicalSciences
Virginia PolytechnicInstituteand State Uniuersity
Blacksburg,Virginia2406I
Abstract
Microprobe analysesindicatethat strontianitesfrom 12 localitieslie essentiallyalong the
and Sro,urCao.r'with Ba and Pb presentat the
CaCOs-SrCO,join betweenSro.r.sCa6.o2,
Lattice parametersvary regularly
2500-3600ppm and the 100-600ppm levelsrespectively.
of SrCOscontent:molepercent
acrossthejoin , with d{srgivingthe bestindirectmeasurement
-2116.24
:
(40.95)
(d,r,
from 3.78for SrCO' to 3.59
range
A).
Densities
+ 1162.84
SrCOa
with valuesin excessof 3.78 indicating that the Ba-Pb contentsare
for SroTusCao.2naCOs,
twinningprecludedmeasure'
presentin more than trivial amounts.Abundant submicroscopic
ment of optical properties.
the standardsand unknownsare of similar composibe accurateto about 2 perAn interestin the strontianiteoccurrencesin the tions, Sr and Ca should
present.
No problemwasencounamount
lower Paleozoiccarbonaterocks of the Appalachian cent of the
Ba
and Pb, althoughtheir
of
in
the
detection
Mountains revealedthe needfor a simplemethodof tered
of the
probablymuchhigherbecause
is
relative
error
Whilethereareseveral
determination.
compositional
problems
the
in
estimating
and
statistics
counting
studiesdealingwith physicalpropertiesof synthetic
I
in
Table
listed
of
cations
The
number
strontianites(Holland et al., 1963:Froeseand Wink- bacrgrounds.
prevent
places
round-off
to
given
four
decimal
to
ler,1966;and Chang,1965,l97l), no work hasbeen are
doneto test their applicabilityto naturalmaterial.In errorsin the calculations.
Unit cell parametersweredeterminedfrom packed
the presentstudy we have examinedthe range of
mounts
of powderedstrontianite,using spinel(a =
and the relachemicalvariationof l2 strontianites
Thesewererun on
tionshipsbetweenchemicalcompositionand some 8.0833A) as an internalstandard.
20/min, using
at
0.25o
diffractometer
a
Norelco
physicalproperties.
CuKo radiation.Eachsamplewas
monochromatized
Experimentalprocedures
scannedat leastoncewith increasingand decreasing
peak
The samplesexaminedin this study are listed in 20. All peaks were measuredat two-thirds
data
of
to
the
reference
with
indexed
height
and
Table 1.Other data from the literatureusedin estabprogramof
(1954).
least-squares
The
et
al.
Swanson
lishingthe determinativecurvesare from Swansone/
(1973)was usedto refinethe
al. (1954), Holland et al. (1963), and De Villiers Applemanand Evans
parameters.
Four
decimalplaceswereretained
lattice
(1971).The 12 strontianiteslisted in Table I were
preventround-off errors in the
to
the
cell
edges
on
analyzedwith an ARL electron microprobe,using
the Eupeon VII computerprogram(Rucklidgeand calculations.
Densitieswere determinedwith the use of a Berused
Gasparrini,1969)for datareduction.Standards
correctedfor
for the elementswere syntheticSrCO' (Sr), calcite man torsion balance,using toluene,
(Pb). Carbonwas temperature,as a displacementliquid. The densities
(Ca), witherite(Ba), and cerussite
determinations
obtainedby calculatingthe numberof carbon atoms of Table I are averagesof several
per
pieces
sample.As
accordinsto the relationC : Sr t Ca * Ba * Pb.As made on two to four different
small
acicutufts
of
as
occur
most of the strontianites
t Presentaddress:3880SardisRoad, Murrysville,Pennsylvania lar crystals,care was taken that air did not remain
trappedbetweenthe fine crystals.
I 5668.
Introduction
l00l
1002
J. A. SPEERAND M. L. HENSLEY.DUNN
Tnslr l Crystaland chemicaldata for strontianites
L3
Sr0
Cao
Pbo
BaO
coz*
Total
60.17
7,26
0.05
0.31
31. 33
99.13
58.33
8.12
0.03
0.37
3r.24
98.09
64.75
3.36
0.09
0.32
30.23
98.74
56.20
9.8s
0,04
0.32
31.68
98.08
ca
Pb
Ba
0,8153
0.1817
0.0004
0.0028
0.7926
0,2040
0.0002
0.0034
0.9094
0.0873
0.0006
0.0030
0.7531
0.243a
0.0003
0.0029
I
1. E891
1.8879
1.8984
1.8830
r.8922
1.8905
1.8850
dr32 c^lc.
1.8897
1.8881
1.8985
1.8839
1.8916
1,8906
1.8853
^?
s.0841(8F*5.0834(7)
8'3317(14) 8.3211(17)
s.9847(r0) 5.9806(9)
2s3'5r(s) 252,97(6'
s.0984(7)
8.3759(14)
6.0115(9)
255.71(5)
s.0746(17) 5.0881(6)
8.3005(26) 8.3389(r2)
5.9687(2s) 5.9920(7)
2s1.41(11) 2s4.24<4)
s.0854(9)
8.3361(20)
s.9869(13)
2s3.80(7)
s.0763(ls) 5.0944(7)
8.30s9(26) 8.3602(16)
5.9743(22) 6.0012(9)
2s1.e0(11) 2s5.5s(6')
5 . 0 8 8 8 ( 1 1 ) s . 1 O 2 E ( 1 4 )5 . 0 9 3 6 ( 6 )
8.3440(22) 8,3992(Ls) 8.3619(12)
s.9917(11) 6.0r97(11) 6.0027(8)
2s4.42(7) 25E.OO(7) 2s5.66(s)
3.63
3.648
3.73
i.718
3.59
3.598
3.66
3.645
3.610
3.668
67 52
6.34
o.o4
0.30
31.16
99.37
Nunbet
v
?r
lneas.
3.59
3.626
60.19
7.r3
0.01
0.35
3I.24
98.93
of
0.8378
0,1598
0.ooo3
0.0021
3.64
3.663
lons
on
56.39
9.08
0.03
0.36
31.17
97.03
the
0.8178
0.179r
0.0001
0. 0032
basis
63.78
4.20
0.02
0.26
30.44
98.70
of
0.7681
O.2286
0.0002
0. 0033
I
61.63
6.11
0.04
0.39
3t.O7
99,24
68.14
1.09
0.08
0,29
29.86
99,46
64.15
s 7. 3 9
7(L9
0.09
0.3r
30.82
99.82
0.07
0.31
32.t2
99.65
29.81
100.00
0.8895
0.1081
0.0001
0.0025
0.8420
0.1s44
0.0003
0.0036
0.9685
0.0287
0.0005
0.0028
0,883t
0.1134
0.0005
0.0028
0.7586
0.2385
0.0004
0.0027
1.9017
1.8954
1.8954
1.8922
7.9022
1,8957
C03
-
3.706
*Caleulated
to gioe C = S? + Ca + Ba + Pb.
**?he eetiruted
stafilard
eyrors ate gioen in papenthese, and refer
ta the Last deeimal place(s)
(Iaphm and Geger, 19?2)
FaALor qw?T!,
WinfieLd,
IJnion Count!, Pennsgloania
(Dietdch,
Salen Rock CmWnA quafrA, Dublin,
PuLaski Count!, Vi"ginia
1960)
D?eneteinfrut,
Wnstet
dist"ict,
Westphalia,
Ceman! (Hardet, 1964)
(Mitchetl
Belton Quafty, Eaet Stone cap, ilise County, Vitginia
and p\@rr, 1961)
(Knapf, 1918)
Itud. HiLLs, Ba?st@, San Bemardina
County, Califomia
CLa! Center, jttM
Caunty, ahio (Monison,
1935; HoM"d, lg'g)
qe?"A,
Frazet Duntile
CLAde Aoenue, Otta6a, Ont@io (Sabim,
1968)
Drensteinftut,
1"fi)n6te" dist?ict,
ile s tpLnlia,
Ceman!1 ( Earde!, 1g 6 I )
SaaLfeld,
Thu?ingia,
cemanA (Na reference
aoaiLabl,e)
70 Silbe?taal,
Silbertaal,
Geman! (No ?efererce
aoailable)
'11
(c"ade and Nackmski,
Mine"Da Mine; Caue in Rock, Hatdin CauntA, tllircis
1949; weller, Grogan and ?ippie,
12 Sauth Pittsburg,
tr4arian Caunt!, ?ennessee (No refeterce
aDailabLe)
'13
Jahnsan MattheA Spec. pu"e S"CO"
3.77
3 . 77 1
3.700
-
1,0000
1.9065
1.8861
r,9062
5.OiE9(8)
8.3154(17)
5.9716(9)
252.20(6'
5.1059(7)
8.4207(t3)
6.0319(11)
259,35(6)
3.594
3.780
1952)
Spindlestagework on what appearedto be opti- of material from the same quarry (#) shows a
cally untwinnedmaterialyieldedalmost identicalB slightlylower CaO content,9.85percent,closerto the
and T values.Checkingthe grainsby X-ray single lower of the two valuesthey reported.In the past,
crystal techniques showed the presenceof sub- there was a question as to whether many of these
microscopic
twinningon (l l0). In general,the refrac- high-calciumcontentswere due to admixture of
tiveindiceswerefoundto increase
with increasing
Ca CaCOr.The microprobeand X-ray resultspresented
content and are approximatedby lines drawn be- here suggestthat this is not the case.
tweenthe refractiveindicesof syntheticSrCOr,a :
The limited compositionalrange of strontianite
1.517,P: 1.663,I : 1.667(Swanson
et al., 1954) coexistingwith a CaCOsphasesuggestsan immiscia n da r a g o n i t a
e :, 1 . 5 3 0 0 , 0 : 1 . 6 8 1 0I , : 1 . 6 8 5 4 bility gap in the systemCaCOs-SrCO".Hollandet al.
(Miilheim, 1888,in Palacheet al., l95l).
(1963)precipitatedstrontianiteand aragonitefrom
aqueoussolutionsat 96'C and demonstratedthe
Resultsand discussion
existenceof an immiscibilitygap between40 and 70
Resultsof the study are summarizedin Table l. mole percentSrCOr.Strontianiteis thoughtto be a
The microprobeanalysesshow the strontianitesex- very low-temperaturemineral,most likely crystallizamined to be essentiallya solid solution along the ing at 0r near l00oC (Helz and Holland, 1965).Its
SrCOr-CaCO,join, with Ca substitutingfor Sr up to occurrencein open vugsand veinssuggests
crystalliabout 25 mole percent.Older analyses
probably at most equal
of CaO con- zation at very low pressures,
tent of strontianites
in Palacheet al. (1951)indicated to the hydrostaticpressure
of the groundwater.The
valuesas high as 7.36weightpercent,well within the rangeof strontianitecompositionsfound in this study
extremevaluesfoundin this study.Recentstrontian- falls within the compositional limits indicated by
ite analyses,many only partial, also fall within the Holland et al. (1963)and predictedfrom the work of
rangeof the samplesin this study,exceptingfor the Chang(1965)for conditionscoincidingwith natural
1l percentCaO contentfound by Mitchelland Pharr conditions.
(1969)for theBeltonQuarrystrontianite.
An analysis The samples studied exhibit very limited sub-
STRONTIANITE COM POSITION AND PHYSICAL PROPERTIES
1003
Ttsre 2. Equationsfor strontianitecompositionfrom cell parametersand density
Correlat
10n
Coef ficient
tion
+ 0 . 9 5 ( E o 1 eZ s r c O r )
0.9928
702,03 (ao,l)
+2,37
o.9523
219.41 (bo,i)
+ 1. 0 0
0,9919
= -2156.62 +
373.83 (co,l)
+2.26
0.9585
=
-734.63 +
3.219
(v,i3)
+o,79
o.9949
=
-367.47 +
123.18 (p
.)
+0.29
0.9988
=
-381.35+
127.33h
)
+ 0 ,4 5
0,9985
oole Z SrCO, = -21]16.24 + LL62.84 (dt32,E)
= -3885.02 +
= -L746.35 +
naE
syn
stitution of Ba and evenlessof Pb. Other strontianite and in Figure l. Measuredvaluesof dB2are listedin
analysesrarely indicate the presenceof these ele- Table I for comparison.From the estimatedstandard
ments,reflectingeither the minor role theseplay or, deviationsand correlationcoefficientsof Table 2, it
of eitherdrs2,b, or V
in the caseof Ba, coprecipitationwith Sr in the wet- would appearthat measurement
determiningSrCOs
for
indirectly
chemicalanalysis.The most Ba- and Pb-richstron- are equallysuitable
dgz using an inof
nieasurement
tianite reportedis from the Suizamine (De Villiers, content.However,
for
its simplicity.
most
appealing
l97l), which contains3.71mole percentBaCO' and ternal standardis
and the
composition
between
The relatignships
0.10 mole percentPbCOs.Theseare an order of
and the
strontianites
for
synthetic
densities
magnitudegreaterthan the Ba and Pb contentsof the ialculated
in
included
are
study
of
this
strontianites
natural
samplesof this study.
densities
2.
Calculated
in
Figure
2
shoyir
Table
and
is
not
the
The minor role of Ba in strontianite
resultof unavailability,for severalstrontianitespeci- were used becauseof the difficultiesin measuring
mens in this study have barite matrices.The same densities.For comirarison,Table I contains the
type of argumentcould be made for Pb, but asso- measureddensitieswhich comparefavorablywith the
ciated Pb mineralsare lesscommon and not as in- calculateddensities.
t i m a t e. C o m p l e t e s o l i d s o l u t i o n s o n t h e
SrCOs-BaCO,and SrCOg-PbCO,joins have been
(Cork
and pressures
at high temperatures
synthesized
and Gerhard, l93l; Chang,1965;Changand Brice,
1972),butan immiscibilitygap at lower temperatures
is still possible.The ionic radius of Sr (-1.30) is
similarto that of Pb (1.33),whereasthe sizedifferencewith Ba (l.47) is nearlythe sameasthat with Ca
ions accordingto Shan- o<
(1.18),for nine-coordinated
non and Prewitt(1969).On this basis,an.immiscibil- AJ
ro
ity gap with BaCOais conceivable(Chang, 1965). E
Immiscibility with PbCOsis lesslikely, and the lack
of intermediatecompositionsmay be the resultof the
rarity of solutionsenrichedin both Pb and Sr.
The samplesin Table I lie essentiallyon the
SrCOg-CaCO,join, and their cell dimensionsare
consistentwith thoseof syntheticstrontianites.The
t88
relation of Sr-Ca content with the various cell parametersfor strontianiteis summarizedin Table 2.
loo
80
90
70
asa
Mole % SrCO5
The d-spacingof the 132peakhasbeensuggested
good indirect measureof strontianitecomposition Frc. l. Calculated values of d* plotted against mole percent
(Froeseand Winkler, 1966).Resultsfor this parame- SrCO, content. The line is the regressionline ofTable 2 calculated
ter usingcalculateddr", arealsopresentedin Table 2 for these spacings and compositions.
1004
J. A. SPEERAND M. L. HENSLEY.DUNN
-
3
o
80
90
M o l e, 7 o S r C O 3
too
FIc. 2. Calculatedvaluesof densltyplottedagainstmole percent
SrCOr content.Solid circlesare syntheticstrontianitesand open
circlesnaturalstrontianites.
Regression
linesaregivenby the equations in Table2, the lower for syntheticstrontianites,
the upperfor
natural strontianites.
The natural strontianitesyield somewhathigher
densitiesthan the syntheticstrontianitesas a resultof
their Ba and Pb contents.The Ba- and Pb-richSuiza
mine strontianite plots well above both curves in
Figure2. In contrastto the cdll dimensions,densityis
very sensitiveto the presenceof theseelements.If
strontianitecbmpositionis determinedusingone of
the cell parameterspacings,a check on densitywill
give an indicationwhetherBa and Pb are presentin
significantamountsor not.
Acknowledgments
We appreciatedonation of specimens
from the Virginia Polytechniclnstituteand StateUniversitycollectionsand the useof the
equipmentof the University'sMolecularStructuresLaboratory.
References
ArrLeueN, DlNrBr-E. lNo Howlno T. EvnNs,Jn. (1973)Job
9214:Indexingand least-squares
refinementof powderdiffraction data. Natl. Tech Inf. Serv., U.S. Dept. Commer.,
Springfield,Virginia,DocumentPB 216 f88.
CHrNc, L. L. Y. (1965)Subsolidusphaserelationsin the systems
BaCO'-SrCOr,SrCOa-CaCOs,
and BaCOr-CaCOg.
J. Geol.73,
346-368.
(1971) Subsolidusphase relationsin the aragonite-type
carbonates:I. The systemCaCOr-SrCOr-BaCO".
Am. Mineral.
56.1660-1673.
AND W. R. Bnlce (1972) Subsolidusphaserelationsin
aragonite-typecarbonates:IL The systemsCaCOr-SrCOrPbCOgand CaCOr-BaCOr-PbCOa.
Am. Mineral.57, 155-168.
Conr, J. M. rxo S. L. GenHeno(1931)Crystalstructureof the
seriesof barium and strontiumcarbonates.Am. Mineral. 16.
't
t-77.
De Vtlltens, J. P. R. (1971)Crystalstructures
ofaragonite,
strontianite,and witherite.Am, Mineral. X,758-76'7.
Dtrrnror, R, V. (1960)Calciostrontianite
from Pulaskiand RockinghamCounties,Ya. Am. Mineral. 45, lll9-1124.
Fnonse, E. ero H. G. F. WTNKLER(1966) The system
CaCOs-SrCOeat high pressuresand 500"C to 7N"C. Can.
Mineral.8,551-566.
Gnewe, O. R. lNo M. P. Nrcrowsxt (1949)Strontianite
and
witheriteassociated
with southernIllinois fluorite.Science.ll0.
331.
Hlnoen, H. (1964)Geochemische
Untersuchungen
zur Geneseder
StrontianitlagerstAttendes Miinsterlandes.Contr. M ineral. Petrogr. 10,198-215.
Herz, G. R. eNn H. D. HollnNo (1965)The solubilityand
geologicoccurrenceof strontianite.Geochim.Cosmochim.Acta,
29,1303-1315.
Hor-r-eNo,
H. D., M. Bnocsrx,J. MuNoz lNo U. M. OxsurcH
(1963)The co-precipitationof Sr+'?with aragoniteand of Ca+'z
with strontianitebetween90o and 100'C. Geochim.Cosmochim.
Acta, 21.95'l-9'17.
Howrno, C. L. H. (1959)Celestiteand fluoritefrom Clay Center,
Ohio. CleuelandMus. Natl. Hist Mus. News, l. 125-130.
Kr.topp,A. (1918)Strontianitedepositsnear Barstow,California.
U. S. Geol.Suru.Bull. ffi 1,25'l-270.
LeeHru, D. M. rNo A. R. Geyen (1972)Mineral collectingin
Pennsylvania.
Penn.Geol.Suru.Bull. G-33, 135-136.
MtTcnrt-t-,R. S. eNo R. F. PHrnn (1961)Celestiteand calciostrontianitefrom Wise County, Virginia. Am Mineral. 46,
I 89-l 95.
MonnlsoN,R. B. (1935)The occurrence
and origin of celestiteand
fluorite at Clay Center,Ohio. Am. Mineral. 20,780-790.
(1951)Dana'sSystem
Pnrncnp,C., H. Brnunu ANDC. FRoNDerof Mineralogy,Vol. 2, 7th edition,John Wiley and Sons,New
York, 196-2@.
Rucrlrocr, J. eNn E. L. GesplnnrNr(1969)Specifications
of a
computerprogramfor processing
electronmicroprobeanalytical data. Toronto, University of Toronto, Dept. of Geology,
3'7p.
SluNn, A. P. (1968)Rocks and mineralsfor the collector,Buckingham-Mont-Laurier-Grenville,
Quebec;Hawkesburg-Ottawa,
Ontario. Geol. Suru. Can. Pap. 6'b5, 54.
R. D. rNo C. T. Pnewrrr 11969)Effectiveionic radii in
SHnNNor.r,
oxidesand fluorides.Acta Crystallogr.B.25,925-946.
SwnNsor.r,
H. E., R. K. Fuynr nNoG. M. UcnrNrc(1954)Standard X-ray diffraction powder patterns. Natl. Bur. Stand. Circ.
539, Volume IlI,73 p.
WELLER,
J. M., R. M. GnocrN ANDF. E. Trerre(1952)Geology
of
the FluorsparDepositsof lllinois. Illinois State Geol.'Suru.Bull.
No. 76, 147p.
Manuscriptreceiued,August 19, 1975;accepted
for publication,February25, 1976