1. Aspectos Técnicos e Económicos do Trabalho da Sonda “Craelius XH” nas Campanhas de Rio Maior e Caldas da Rainha.
A. Rodrigues Cavaco (29 pages)
Abstract: In this article the autor presents some of the results obtained in two drilling campaigns in Rio Maior’s lignite basin and «tiphonic» area of Caldas da Rainha – Óbidos, with a Craelius XH apparatus. These were the first campaigns carried out with that drilling machine; 3289,02 m were drilled, distributed among 20 drill holes, 5 in the Caldas-Óbidos area (1180,36 m) and the others in Rio Maior (2180,66 m). In this paper, technical and economical aspects of the utilization of Craelius XH Drilling Machine are shown in detail, during a little more than two and half years. (…)The campaign in this area was much more difficult than in Rio Maior because of the drilling of factured limestones cementations and accidents, during a very severe winter, as may be seen in some of the photographs. The results show the adaptation of workers that had to be instructed, and the economy already made by the State with the acquisition of such drilling machine. Apart from that is enabled us to have already estimated the reserves in the deposit at Rio Maior and to have already done the borings recommended by the seismical prospection of alcaline salts of Caldas-Óbidos area.
(…) Parcial Abstract
2. Breve Estudo Sobre o Jazigo de Manganês da Cova da Moura.
C. da Conceição Fernandes (25 pages)
Abstract: The place where this deposit is localized is part of the great palaeozoic area of the Low Alentejo, constituted by the schists of various colours where the outcrops of jasperoid quartzites are laid. The ore can be found in the contact of quartzites with the schists, in the quartzites themselves, in form of nests, druses, geodes, kidneys, small wrinkles and also intercalated in the schists as veins, small veins or lenses and even lodes. In the filling the following minerals can be identified: quartz, pyrite, galena, malachite, barite and also argils of various colours.The ore is mainly formed by granular massive manganese oxides – psilomelane sometimes with slight presence of pyrolusite – and also by oxides of earth aspect – wads. The percentage in Mn reaches sometimes 53%, the silica varying between 1 to 11%. In the ore chosen among the quartzites the silica increases a good deal accompained by improverishment in Mn. The depth attained by the concentration is, on the average, 12 meters. Below this depth we find quartzites with accentuated presence of iron oxides. The nature to the deposit – small and dispersed concentration – does not alow a calculation of reserves. The small nucles of mineral bear witness to the existence of some hundreds of tons. This deposit is of a difficult and not very economical exploitation, owing to the dispersion of the concentrations and hardness of the rock to be dismounted.
3. Les Minerais de Fer Portugais.
J. M. Cotelo Neiva (13 pages)
Abstract: Siderite – At the Guadramil deposit, of the Ordovician, with some millions of tons of reserves, the siderite ore, presenting an oolitic texture, is constituted of oolites of siderite, silex and some of chamosite, cemented by siderite and calcite. It alters at the surface to limonite, stillpnosiderite, some goethite and chlorite, and in the faulty zones was metamorphosed to specularite. The ore averages in Fe, it ranging from phosphorous to average phosphorous.To be used it has to be calcinated. Hematite – At the Moncorvo deposit (folded and metamorphosed rocks of the Ordovician) there are hundreds of millions of tons of reserves of more of an order ranging from grano-nematoblastic to porphyro-granonematoblastic texture.
The ore consists of martite, specularite, quartz and sericite, and, accessorily, of chlorite, albite, apatite, and lazulite. It ranges from average to rich in Fe, and ranging from phosphorous to average phosphorous, and contains SiO2 in a rather high percentage; concentration is not practical from an economical point of view and the ore must therefore be used as it appears. Magnetite – At the Vila Cova do Marão deposit (with the Ordovician rocks strongly folded and metamorphosed) there are some tens of millions of tons of ore of a grano-lepidoblastic texture, constituded of magnetite, quartz and chlorite, and, accessorily, of apatite, zircon, rutile and albite.
The ore ranges on from average to rich in Fe, and from practically pure in S and P to slightly phosphorous; there is a rather high percentage of SiO2, but it can be easily concentrated with the electro-magnetic separator by eliminating P (apatite) and practically SiO2 (quartz and silicates).
The deposits at Alentejo, pyrometasomatic and of magmatic segregation and related to the activities of perioditic and gabro-dioritic magmas, are dispersed and total some millions of tons of reserves and frequently present a lenticular structure. Magnetite is allied to the carbonate gangue (calcite and dolomite) of granoblastic texture, or to the silicate gangue (pyroxenes, amphiboles, olivine and serpentine minerals) of an order ranging from granoblastic to grano-lepidoblastic texture, or to silicate-carbonate gangue (garnets and minerals of the carbonate and silicate gangues), and sometimes allied to sulphides (pyrite, pyrrhotite and chalcopyrite).
The ore ranges from average to rich in Fe, pure to slightly phosphorous and is rather high in S and SiO2. To be used it must be burnt and concentrated with an electro-magnetic separator. Limonite, lepidocrocite and goethite – At the Rates deposit, the limonitic ore, which is found in rather large quantities, and bedded in schists of the Lower Devonian, is essentially constituted of limonite, and, accessorily, of goethite, lepidocrocite and quartz. The ore is rich in Fe, ranging from phosphorous to average phosphorous.
It may be easily hand picked. At the Odemira-Cercal (Alentejo) iron-manganese deposits, totaling some millions of tons of reserves, to lepidocrocite are allied pyrolusite, and, accessorily, goethite, limonite, hematite, psilomelane and wad; less commonly, turgite, stillpnosiderite, braunite, and, occasionally, kraurite and diadochite-destizenite; the gangue minerals being quartz and barite. The ore presents a colloform structure and ranges from average to rich in Fe, average phosphorous and with an interesting percentage of Mn. It may be easily hand picked.
4. Minas de Ferro dos Arredores de Moura.
Carlos de Araújo (10 pages)
Abstract: O concelho de Moura foi objecto de pesquisas e explorações mineiras desde os remotos tempos da Idade do Bronze (mina de Ruy Gomes) até à Idade Contemporânea. Esta actividade, porém, só começou a ser organizada por volta do Século XIX, nomeadamente a partir de 1852, data dos registos mineiros mais antigos da região.Pode afirmar-se que sobre quase toda a área adjacente à vila de Moura incidiram manifestos mineiros, uns originados pelo aspecto enganador de pequenas mineralizações e outros pelos próprios proprietários dos terrenos para obstarem à fúria das pesquisas.
Conhecido o carácter da nossa missão neste concelho, começaram a afluir não só informações da existência de mineral em vários pontos desta região, como também amostras encontradas por curiosos. Houve que proceder a uma investigação sobre as possibilidades mineiras apontadas e, por esse motivo, foram estudados os terrenos delimitados na planta n.º 1.
Outros locais mais afastados e aos quais se não faz referência especial, por obedecerem a características idênticas aos terrenos que se descrevem adiante, são os seguintes: Montalvo, Pecegueiro, Pai Mogo, Tapada e Machados.
5. Relatório do Serviço de Fomento Mineiro do Ano de 1951.
J. L. Guimarães dos Santos (57 pages)
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