American Mineralogist, Volume 73. pages422-423, 1988
A system of nomenclature for rare-earth mineral species: Revision and extension
Pornn Blvr.rss, A. A. LrcvrNsor.q
Department of Geology and Geophysics, The University
of Calgary, Alberta T2N 1N4, Canada
ABSTRACT
Revisions to an earlier paper on the nomenclature of rare-earth mineral speciesare
reported. Now, only the dominant element in a specifiedcrystal-structuresite within isostructural minerals may be appended to the group name as a parenthesizedsuffix. This
nomenclaturesystemis mandatory for rare-earthmineral species.More than one chemical
symbol may be appended only if the elements occupy diferent crystal-structure sites,
which must be defined. Before publication of any new mineral name, approval is required
from the Commission on New Minerals and Mineral Names (CNMMN of the International Mineralogical Association.
INrnonucrroN
In addition, this nomenclaturesystemwas recently made
mandatory for all new rare-earth mineral species(Nickel
and Mandarino, 1987).New mineral namesconforming
to this usagemust be approved before publication by the
CNMMN.
Levinson(1966,p. 155)proposedthat "If a rare-earth
mineral contains considerablequantities of a rare-earth
elementwhich is unusual,or for any reasonmerits notice,
two or more chemical symbols may be placed in the pa'considerable' quantity is
rentheses.In these cases,the
not high enough to warrant the speciesdesignation,i.e.,
the respectiveelementis not predominant.For example,
a monazite-(Ce)with a considerableamount of samarium
would be written as monazite-(Ce,Sm).The first symbol,
Ce in this case,representsthe species,whereasSm is an
element which occurs in important amounts." This noDnr.rNrrroNs
menclaturesystemhasbeenfollowedby Andersen(1986)
A group name is given to a rare-earth mineral that has with monazite-(Ce,Nd). However, modification of this
been identified without detailed chemical analysis of the particular aspectof the nomenclaturesystemis desirable.
rare-earth elements,e.g., monazite. Each rare-earth anaWhen two or more chemical symbols within parenthelogue,i.e., mineral species,within the group must be iso- sesare suffixed, the secondchemical symbol may mean
structural.
either (a) a chemical variety or (b) a mineral species;i.e.,
A speciesname is given to a rare-earth mineral when- the secondchemical symbol representsa rare-earth eleever the rare-earth element distribution has been deter- ment in a different crystal-structuresite compared to the
mined. The chemical-symbol for the predominant rare- first chemical symbol. Ancylite-(Ce) has rare-earth eleearth element is appended,in parentheses,by means of ments in four different crystal-structuresites (Szymafiski
a hyphento the group name;this resultsin mineral-species and Chao, 1986). Therefore, the CNMMN has recently
names such as monazite-(Ce),monazite-(La), and mon- approved a modification to the original nomenclature
azite-(Nd). Therefore,all rare-earth mineral speciesmust system (Levinson, 1966) such that a chemical adjectival
have a chemical-symbol suffix (Nickel and Mandarino, modifier should be used instead of two or more chemical
1987).
if two or more elementssubsymbolswithin parentheses
The nomenclature system of chemical-symbol sufrxes
describedby Levinson (1966) originally only applied to
rare-earth mineral species,which are defined to have the
total atomic percentageof the rare-earth elementsand Y
greaterthan any other elementwithin a singlesetof crystal-structure sites, e.g., (>REE,Ca). Of the 14 rare-earth
elements(La through Lu) and Y, 6 have been observed
to predominate in mineral specieson the basis of atomic
percentageof rare-earth elements within a single set of
crystal-structuresites. The rare-earth mineral speciesin
order of abundanceare Y (59),Ce (5 l), Nd (13), La(12),
Yb (2), and Gd (1). The numbers in parenthesesare the
numbers of mineral speciesin which the particular rareearth element predominates.
Drscussrou
This nomenclature systemwas made retroactive (Levinson, 1966) by the discreditation of abukumalite [now
britholite-(Y)1, doverite [now synchysite-(Y)], priorite
[now aeschynite-(Y), and spencite [now tritomite-(Y)].
0003-004x/88/03044422$02.00
:lTJ::,3:;il1;'*l"T':?iiJ;"tf,l"Jili,'.1
for the first time.
The example of monazite-(Ce,Sm)should now be written as samarianmonazite-(Ce).The reasonsfor the modifications to the original nomenclature system are as fol-
422
BAYLISS AND LEVINSON: NOMENCLATURE FOR RARE-EARTH MINERALS
lows: (a) Greater uniformity will result since all mineral
specieswould follow the chemicaladjectival modifier rule;
(b) alteringthe end ol'a mrneralspeclesname [e.g.,monazite-(Ce)with designationssuch as Sm and Ndl, would
create numerous varietal names; and (c) special characters, like commas,have been used for computer sorting
or searching,so that they should be avoided in mineral
names,if possible.
AcrNowr,tlcMENTS
Dr. E. H Nickel, vice-chairman of the CNMMN, provided advice.
Financial assistancewas provided by the Natural Sciencesand Engineering ResearchCouncilofCanada.
423
RnrnnnNcrs crrnl
Andersen,Tom ( I 986) Compositional variation of some rare earth minerals from the Fen complex (Telemark, SE Norway): Implications for
the mobility of rare eaIlhs in a carbonatesystem.Mineralogical Magazine,50, 503-509
Levinson,A A. (1966)A systemofnomenclaturefor rare-earthminerals
AmericanMineralogist,5 l, I 52-l 58
Nickel, E.H , and Mandarino, J.A (1987)Proceduresinvolving the I.M.A'
Commission on New Minerals and Mineral Names, and guidelineson
mineral nomenclature American Mineralogist, 72, 103| -1042.
Szymairski,J.T., and Chao, G Y (1986)The crystalstructureofmonoclinic ancylite (abs) American CrystallographicAssociation, Annual
Meeting, Hamilton, Paper PA2.
Fesnu,Anv5, 1987
MeNuscnrrr REcETvED
MeNuscnrrr AccEprEDNovprr.rapn20, 1987