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Clinohydroxylapatite; a new apatite-group mineral from northwestern Ontario (Canada), a new data on the extent of Na-S substitution in natural apatites

Anton R. Chakhmouradian and Luca Medici
Clinohydroxylapatite; a new apatite-group mineral from northwestern Ontario (Canada), a new data on the extent of Na-S substitution in natural apatites
European Journal of Mineralogy (February 2006) 18 (1): 105-112

Abstract

Clinohydroxylapatite, the monoclinic natural analogue of hydroxylapatite, occurs in altered leucogabbro in one of the units in the Mesoproterozoic Seagull pluton in NW Ontario. It forms as masses of coalescent spherulites < 30 mu m in diameter developed metasomatically after igneous plagioclase, and is paragenetically associated with prehnite, hibschite, titanite, rutile and an unidentified Ca silicate. It is white with H. 5, D 3.07 g/cm (super 3) ; alpha 1.632, gamma 1.649. Compositionally, it is an intermediate member of the ternary system Ca (sub 5) (PO (sub 4) ) (sub 3) (OH)-Ca (sub 5) (PO (sub 4) ) (sub 3) Cl-Na (sub 3) Ca (sub 2) (SO (sub 4) ) (sub 3) (OH). The average content of the latter two end-members is approximately 20 mol% each.The combination of high Na and S (up to 0.63 and 0.71 pfu) is unparalleled by any previously reported natural composition, and indicates significant solubility of these elements in natural apatites, even at low temperatures of crystallization. Indexed XRD powder data are tabulated; strongest lines 2.267(100), 2.724(79), 1.784(70), 2.817(66), 1.841(58) Aa; a 9.445, b 18.853, c 6.8783 Aa, gamma 120.00 degrees , Zeta = 4, space group P2 (sub 1) /b. The deviation from the archetypal (space group P6 (sub 3) /m, a approximately 9.4, c approximately 6.9 Aa) probably results from ordering of the (OH) (super -) anions in [00z] anionic columns and consequent doubling of periodicity along [010].


ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 18
Serial Issue: 1
Title: Clinohydroxylapatite; a new apatite-group mineral from northwestern Ontario (Canada), a new data on the extent of Na-S substitution in natural apatites
Affiliation: University of Manitoba, Department of Geological Sciences, Winnipeg, MB, Canada
Pages: 105-112
Published: 200602
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 46
Accession Number: 2006-036665
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 4 tables
N42°00'00" - N57°00'00", W95°00'00" - W74°00'00"
Secondary Affiliation: Istituto di Metodologie per l'Analisi Ambientale, ITA, Italy
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 200620
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