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<article article-type="research-article">
<front>
<journal-meta>
<journal-id journal-id-type="archive">gsminmag</journal-id>
<journal-title>Mineralogical Magazine</journal-title>
<abbrev-journal-title abbrev-type="full">Mineralogical Magazine</abbrev-journal-title>
<issn pub-type="ppub">0026-461X</issn>
<publisher>
<publisher-name>Mineralogical Society</publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.1180/minmag.1991.055.381.01</article-id>
<article-categories>
<subj-group subj-group-type="heading">
<subject>Mineralogy</subject>
</subj-group>
</article-categories>
<title-group>
<article-title>Vanadian Allanite-(La) and Vanadian Allanite-(Ce) from the Hemlo Gold Deposit, Ontario, Canada</article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname>Pan</surname>
<given-names>Yuanming</given-names>
</name></contrib>
<contrib contrib-type="author">
<name>
<surname>Fleet</surname>
<given-names>Michael E.</given-names>
</name></contrib>
<aff>Department of Geology, University of Western Ontario, London, Ontario N6A 5B7, Canada</aff></contrib-group>
<pub-date pub-type="ppub">
<month>12</month>
<year>1991</year>
</pub-date>
<volume>55</volume>
<issue>381</issue>
<fpage>497</fpage>
<lpage>507</lpage>
<history>
<date date-type="received">
<day>28</day>
<month>11</month>
<year>1990</year>
</date>
<date date-type="rev-recd">
<day>20</day>
<month>2</month>
<year>1991</year>
</date></history>
<copyright-statement>Copyright &#x00A9; 1991, The Mineralogical Society</copyright-statement>
<copyright-year>1991</copyright-year>
<abstract>
<title>Abstract</title>
<p>Allanite-(La) (containing up to 7.80 wt.% V<sub>2</sub>O<sub>3</sub> and with La/&#x03A3;<italic>REE</italic> and La/Ce atomic ratios up to 0.54 and 1.45, respectively) and allanite-(Ce) (up to 8.46 wt.% V<sub>2</sub>O<sub>3</sub>) occur in close association with vanadian muscovite, barian tomichite and vanadian titanite in the main ore zone of the Hemlo gold deposit, Ontario, Canada. Allanite-(Ce) generally occurs as a minor constituent in cross-cutting veins or along foliation planes, whereas allanite-(La) invariably occurs in direct contact with titanite. The high V concentrations in the allanites from Hemlo are readily attributable to an adequate local source of this element, and are most likely controlled mainly by a simple substitution of V for Al in octahedral coordination. Vanadian allanite-(La) and vanadian allanite-(Ce), without any systematic differences in other constituents, are clearly distinct in <italic>REE</italic> composition, in respect to both the relative concentrations of La and Ce and abundances of other <italic>REE</italic>. The formation of both allanites (Ce- and La-rich) indicates very localised remobilisation and concentration of <italic>REE</italic> during a late hydrothermal alteration. The unusual <italic>REE</italic> composition of vanadian allanite-(La) directly reflects partitioning of <italic>REE</italic> with coexisting titanite, and the formation of this unusual phase may be attributable to replacement of earlier titanite with redistribution of <italic>REE</italic> in the solid state.</p></abstract>
<kwd-group>
<title>Keywords</title>
<kwd>allanite-(La)</kwd>
<kwd>allanite-(Ce)</kwd>
<kwd>vanadian allanite</kwd>
<kwd><italic>REE</italic> mobility</kwd>
<kwd>titanite</kwd>
</kwd-group>
</article-meta>
</front>
</article>
