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Scandian actinolite from Jordanów Śląski, Lower Silesia, Poland: Compositional evolution, crystal structure, and genetic Implications.
- Source :
- American Mineralogist; Jan2024, Vol. 109 Issue 1, p174-183, 10p
- Publication Year :
- 2024
-
Abstract
- Scandian actinolite evolving to scandio-winchite (up to 5.45 wt% Sc<subscript>2</subscript>O<subscript>3</subscript>) has been found in chloritedominant xenoliths incorporated into marginal portion of a granitic pegmatite. The pegmatite intruded a blackwall schist zone developed around rodingite-type rocks exposed in a serpentinite quarry at Jordanów Śląski near Sobótka, ~30 km south of Wrocław, Lower Silesia, Poland. The amphiboles form irregular overgrowths around cascandite and represent a complex solid-solution series among actinolite and scandio-winchite end-members, with a trace contribution of "scandio-magnesio-hornblende." Structural studies of a scandian actinolite crystal with composition <superscript>A</superscript>[□<subscript>0.995(2)</subscript>K<subscript>0.005(2)</subscript>]<subscript>Σ1</subscript><superscript>B</superscript>[Na<subscript>0.24(5)</subscript>Ca<subscript>1.73(4)</subscript>]<subscript>Σ1.98(1)</subscript> C M g 3.74 (7) F e 0.90 (3) 2 + M n 0.04 (1) S c 0.26 (3) A l 0.05 (1) Σ 4.99 (1) T S i 7.98 (2) A l 0.02 (2) Σ 8.00 O 22 (O H) 2 revealed monoclinic C2/m structure with unit-cell parameters a = 9.8517(3), b = 18.0881(6), c = 5.28501(18) Å, β = 104.809(4)°, in which scandium is located solely at the <superscript>C</superscript>M2 site. Scandian amphiboles are uncommon in geological environments, and invite comments on the origin of the observed Sc enrichment in the amphibole structure. Textural appearance of the chlorite-cascandite-amphibole clusters suggests that the formation of the amphiboles is related to the evolution of the country rocks followed by partial alteration of blackwall schist xenoliths by pegmatite-forming melt. [ABSTRACT FROM AUTHOR]
- Subjects :
- CRYSTAL structure
AMPHIBOLES
SERPENTINITE
INCLUSIONS in igneous rocks
SCANDIUM
Subjects
Details
- Language :
- English
- ISSN :
- 0003004X
- Volume :
- 109
- Issue :
- 1
- Database :
- Complementary Index
- Journal :
- American Mineralogist
- Publication Type :
- Academic Journal
- Accession number :
- 174520712
- Full Text :
- https://doi.org/10.2138/am-2022-8786