000			02444caa a22003134a 4500
001			42063
003			AR-SsjUBGM
005			20251222143702.0
008			251215nuuuuuuuuag 000 0 spa d
040			_aAR-SsjUBGM _cAR-SsjUBGM
044			_aag
100	1		_aColombo, Fernando _958827
245	1	0	_aMineralogical characterization of topaz from miarolitic pegmatites and w-bearing greisen in the a-type El Portezuelo granite, Papachacra (Catamarca Province).
500			_aRelevamiento: 2009.
520	3		_aThe El Portezuelo Granite (Catamarca Province, NW Argentina), probably of Late Devonian or Early Carboniferous age, was emplaced at = 2 kbar and displays the chemical characteristics of an A-type granite. It hosts small miarolitic pegmatites and dikes that belong to the NYF petrogenetic family, miarolitic class, miarolitic-REE subclass, with features more similar to those reported for the gadolinite-fergusonite type. Topaz is widespread both in pegmatites and in a W-bearing greisen genetically related to the granite. In pegmatites it occurs as crystals up to over 15 cm long, showing the forms {120} and {041} (dominant), and also {100}, {010}, {001}, {110}, {130}, {230}, {410}, {150}, {340}, {201}, {203}, {011}, {021}, {031}, {111}, {112}, {221}, {223}, and {445}. Crystals are colorless to pale yellow, more rarely brownish or bluish. Electron-microprobe analyses of gemmy crystals from pegmatites and greisen show that topaz is F-rich (between 19.01 and 20.12 wt. por ciento F, most crystals being slightly zoned) and has very low MgO and TiO2 (= 0.02 wt. por ciento), low FeO (=; 0.03 wt. por ciento), and up to 0.10 wt. por ciento CaO. Refractive indices and unit-cell dimensions reflect the F-rich nature of the studied topaz. This occurrence produces the finest crystals yet known from western South America but probably has no economic potencial as gemstock producer.
530			_aArtículo en pdf (RAGA 64_2_194.pdf)
650		4	_aGranito tipo a
650		4	_aPegmatita
650		4	_aTopacio
651		0	_aCatamarca _96203
651		0	_aEl Portezuelo _958830
655		4	_aArtículo _924605
700	1		_aLira, Raúl _958831
700	1		_aPannunzio Miner, Elisa V. _958832
710	2		_aAsociación Geológica Argentina _eeditor _920581
773	0		_tRevista Asociación Geológica Argentina _gvol.64, no.2, p.194-200 _x0004-4822
942			_cAR _2cdu
945			_aidgym _d2009-09-30
999			_c42063 _d42063