Descrição

Artigos

1. Géologie et Genèse des Gisements Portugais d’ Apatite.
J. M. Cotelo Neiva ; N. Múrias de Queiroz ; F. Limpo de Faria (14 páginas)
Resumo: The Portuguese apatite deposits are situated in the regions of Medelium and Marvão-Castelo de Vide; they are embedded in the alkaline granite of engadinitic chemism, and this may probably be related to the saalic phase of the hercinian movements.They are veins set NNE-SSW to NE-SW and essentially constituted of quartz and fluorapatite of several generations, with some felspars (orthoclase and albite), muscovite, magnetite, zircon, tourmaline, sericite, arsenopyrite, pyrite, montmorillonite, torbernite, and bauerite. There must have been in the genesis of these deposits a small pegmatitic phase as well as several developed hydrothermal phases, some of these being mixed with pneumatolytic phases.
There is a reference to the paragenesis of the minerals in the table on page 277. Granite has in contact with the deposits undergone microclinization, albitization, tourmalinization, chloritization, sericitization, silicification, meroxenization, montmorillonitization and kaolonization.

2. O Doseamento do Estanho em Minérios de Volfrâmio.
R. A. Guedes de Carvalho (264 páginas)

3. Rochas Eruptivas das Chãs (Vila Nova de Foz Côa) e seu Interesse para a Prospecção de Minerais das Terras Raras.
J. M. Cotelo Neiva ; F. Limpo de Faria (8 páginas)
Resumo: A two-mica-porphyritic-granite, alkaline orthosic granite I. 4. 1.3 of engadinitic chemism, is found in Chãs (Vila Nova de Foz Côa). A biotite-syenite II 5.2.3, of opdalitic chemism, and with natronsyenitic affinity, outcrops in this rock. Crossing the biotite-siyenite there is a syenite-pegmatite I (II). 5. (1) 2. (2) 3 of a possible plagioclase granitic chemism but with great affinities with nordmarkitic-pulaskitic and natronsyenitic magmas.The rocks of syenitic composition present radio-active allanite and sphene which may also be radio-active. We can logically admit that monazite occurs in these rocks. The study of this region is very interesting due to the appearance of minerals of rare earths.

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