| Abstract: | At Hurricane Mountain, Carroll County, New Hampshire, bodies of granitic pegmatite in riebeckite granite contain large (up to 10 cm long and 2 cm across) primary crystals of Li-bearing fluor-arfvedsonite in miarolitic cavities, grading to euhedral Li- and F-poor arfvedsonite. Fine-grained, fibrous, light blue-gray riebeckite occurs as a late-stage hydrothermal filling in the miarolitic cavities. The early, Li-rich, fluor-arfvedsonite has: a 9.836(5), b 17.997(7), c 5.316(4) A??, ?? 103.735(4)??, V 914.20(6) A??3; Z = 2, Dmeas. 3.34 g/cm3, Dcalc. 3.353 g/cm3; biaxial (-), 2Vmeas. 44(1)??, 2Vcalc. 46??; ?? 1.681(2), ?? 1.692(2), ?? 1.694(2), inclined dispersion, r > v; X ??? c -7??, Y = b, Z ??? a +7??; X dark blue, Y lavender gray, Z pale yellowish brown; X > Y > Z; X is opaque at 0.03 mm thickness. A structural formula, on the basis of 24 (O,OH,F) atoms is: (Na0.86K0.25)Na2(Fe2+2.54Fe3+1.485Mn0.10Zn 0.02Li0.49Ti0.07)(Si7.71Al 0.07)O22(F1.34OH0.63). Arfvedsonite within the miarolitic cavities contains less Li and F than that of the earlier generation, and the still later riebeckite contains only 0.09 wt.% Li2O and 0.3 wt.% F. The Fe3+:Fe2+ ratio of the early Li-bearing fluor-arfvedsonite and that of the euhedral arfvedsonite crystals within miarolitic cavities is 0.58. The late, fibrous, cavity-filling riebeckite has an Fe3+:Fe2+ ratio of 0.99. The total iron content of the three amphiboles increases with continued crystallization. These amphiboles are products of peralkaline pegmatites locally derived from peralkaline granite. |
| Genre: | Article |
| ProdID: | 70018138 |
| Citation Author: | Foord, E. E.; Erd, R. C.; Robie, S. B.; Lichte, F. E.; King, V. T. |
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| Citation End Page: | 1014 |
| Citation Issue: | 5 |
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| Citation Language: | English |
| Citation Larger Work Title: | Canadian Mineralogist |
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| Citation Number Of Pages: | 4 |
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| Citation Search Results Text: | Li- and F-bearing alkali amphibole from granitic pegmatite at Hurricane Mountain, Carroll County, New Hampshire; 1996; Article; Journal; Canadian Mineralogist; Foord, E. E.; Erd, R. C.; Robie, S. B.; Lichte, F. E.; King, V. T. |
| Citation Start Page: | 1011 |
| Citation Volume: | 34 |
| Citation Year: | 1996 |
| Type: | citation/reference |
| Text: | Li- and F-bearing alkali amphibole from granitic pegmatite at Hurricane Mountain, Carroll County, New Hampshire; 1996; Article; Journal; Canadian Mineralogist; Foord, E. E.; Erd, R. C.; Robie, S. B.; Lichte, F. E.; King, V. T. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Mon, 1 Jan 1996 00:00 -0600 |
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