Skip to Main Content
GEOREF RECORD

Holtstamite, Ca (sub 3) (Al,Mn (super 3+) ) (sub 2) (SiO (sub 4) ) (sub 3-x) (H (sub 4) O (sub 4) ) (sub x) , a new tetragonal hydrogarnet from Wessels Mine, South Africa

Ulf Halenius, Ulrich Haussermann and Hans Harryson
Holtstamite, Ca (sub 3) (Al,Mn (super 3+) ) (sub 2) (SiO (sub 4) ) (sub 3-x) (H (sub 4) O (sub 4) ) (sub x) , a new tetragonal hydrogarnet from Wessels Mine, South Africa (in EMPG X; Experimental mineralogy, petrology and geochemistry, A. B. Woodland (editor) and S. F. Foley (editor))
European Journal of Mineralogy (April 2005) 17 (2): 375-382

Abstract

Holtstamite occurs in a calc-silicate skarn together with Mn-rich vesuvianite, calcite and henritermierite, at the Wessels mine, South Africa. It is transparent and pale brownish yellow with a vitreous lustre; H 6, D (sub calc) 3.25 g/cm (super 3) ; omega (pale orange) 1.718, epsilon (lemon yellow) 1.746. EPMA results show extensive holtstamite-henritermierite solid solution; the octahedral occupancy in holtstamite is characterized by Al > Mn (super 3+) and the most Al-rich tetragonal hydrogarnets in the present sample contain from approximately 23 to approximately 69 mol.% of the hypothetical tetragonal end-member Ca (sub 3) Al (sub 2) (SiO (sub 4) ) (sub 2) (OH) (sub 4) . Indexed XRD powder data led to the cell parameters a 12.237, c 11.930 Aa, space group I4/acd. A crystal structure refinement (R 3.57%) on a crystal with the mean composition Ca (sub 3) (Al (sub 0.96) Mn (super 3+) (sub 0.68) Fe (super 3+) (sub 0.37) )(SiO (sub 4) ) (sub 2.00) (H (sub 4) O (sub 4) ) (sub 0.99) shows distinctly shorter octahedral bond lengths (mean M1-O 1.976 Aa) than for henritermierite (mean M1-O 2.020 Aa) and a considerably smaller octahedral axial ratio (1.085) as compared to henritermierite (1.144). It is suggested that the stabilization of the tetragonal Al-dominant calcic hydrogarnet may require a fraction of Mn (super 3+) at the octahedral M1site. The FTIR sectrum is presented. The name is for Dr Dan Holtstam (1963-) to honour his contribution to the mineralogy of Mn-deposits of Langban type.


ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 17
Serial Issue: 2
Title: Holtstamite, Ca (sub 3) (Al,Mn (super 3+) ) (sub 2) (SiO (sub 4) ) (sub 3-x) (H (sub 4) O (sub 4) ) (sub x) , a new tetragonal hydrogarnet from Wessels Mine, South Africa
Title: EMPG X; Experimental mineralogy, petrology and geochemistry
Author(s): Halenius, UlfHaussermann, UlrichHarryson, Hans
Author(s): Woodland, A. B.editor
Author(s): Foley, S. F.editor
Affiliation: Swedish Museum of Natural History, Department of Mineralogy, Stockholm, Sweden
Pages: 375-382
Published: 200504
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
Meeting name: 10th international symposium on Experimental mineralogy, petrology and geochemistry
Meeting location: Frankfurt, DEU, Federal Republic of Germany
Meeting date: 20040404April 4-7, 2004
References: 20
Accession Number: 2005-041710
Categories: Mineralogy of silicates
Document Type: Serial Conference document
Bibliographic Level: Analytic
Illustration Description: illus. incl. 4 tables
S35°00'00" - S22°00'00", E16°00'00" - E33°00'00"
Secondary Affiliation: Stockholm University, SWE, SwedenUppsala University, SWE, Sweden
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 200525
Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal