Mineral Resources of Minas Geraes (Brazil)E. & F. N. Spon, 1915 - 127 sider |
Andre udgaver - Se alle
Almindelige termer og sætninger
Agua Limpa auriferous Bahia Barbara beds Bello Horizonte Branca Brazil Brazilian Mining canga capital Caraca carats carbonate cascalho Caué cent Conceicao depth Derby Diamantina diamonds estimate geological Gold Mining Gongo Soco Gorceix Goyaz hematite industry iron deposits IRON DISTRICT IRON ORE DEPOSITS Itabira do Campo Itabira do Matto itabirite jacutinga John del Rey Kilburn Scott kilometres Lake Superior Lake Superior region lode manganese Maquiné Marianna massive hematite Matto Grosso metres mica micaceous MIGUEL BURNIER MINES miles million tons Minas Geraes mineral Mining Company Mining Engineers Morro Velho mountains ore-body Ouro Ouro Preto outcrops Paracatu Passagem Pico d'Itabira Piedade PITANGUY PLATE pyrites quantity quartz quartzites QUELUZ railway Rey Mining rich Rio de Janeiro river rock rubble Sabara Santa Sao Bento Sao Paulo Sao Vicente schists secondary concentration Serra Serra do Espinhaço shaft silica stones surface thickness tion transport Wigg
Populære passager
Side 16 - ... to a rock composed of micaceous specular iron ore, compact specular iron, rarely laminated, a little oxide of iron and quartz disseminated. It is the rock of which the Peak of Itabira and the Serra da Piedade are composed. Burton describes the jacutinga as follows : f " This substance, of iron black with metallic lustre, sparkles in the sun with silvery mica ; the large pieces often appear of a dark reddish brown, but they crumble to a powder almost black. The constituents are micaceous...
Side 92 - MICA MINING IN BRAZIL. To the countries enumerated in Section (2) must now be added Brazil. Mica occurs in workable quantities in three of the Brazilian States, viz., Goyaz, Bahia, and Minas Geraes. No exact information is available with regard to the deposits of mineral in Goyaz or Bahia, the quantity of mineral exported from the States having been very small, though it should be stated that the mica from the State of Goyaz is of excellent quality. The principal mica deposits are pegmatite veins,...
Side 44 - This shows all possible gradations from an almost pure quartz rock with scattered flakes of hematite to a massive hematite free from quartz. The latter presents itself as intercalated layers, or lenses, varying from a few milimetres up to scores of metres in thickness, alternating with leaner quartzoze portions.
Side 17 - ... tunnel can be driven up from lower down the valley and will more or less follow the strike of the country. The length of the adit would be under a mile, and it would come to well below the bottom of the old mine, so that it would drain all the water out of the formation '. Richard Burton1 said : ' In this mine the gold was free and the plundering was enormous — some say to the extent of one-half the find. Tales are still told of miners going out on Sundays carrying guns filled with stolen ore...
Side 85 - The satellites are extremely numerous, and comprise various jaspers, amethysts and chalcedonies, rose zircons, anatase, almandine garnets, white topazes, sphenes, native silver, etc., etc. The diamonds are small, the largest found being 5 carats. The form is usually dodecahedron with well curved faces. The surrounding formation is schists and quartzites. No carbonates or boart is found. Several dredges have been at work in this river.
Side 44 - In its essential geological features the region is constituted by a basement complex of crystalline schists (gneiss, mica-, amphibole-, chlorite-, and talcose-schists) much injected with granite, and overlaid by a heavy series of partially metamorphosed sedimentary beds, profoundly folded and faulted. In this series, which consists principally of quartzites and clay slates with subordinate beds of limestone, a prominent member is the peculiar iron-bearing quartzite to which the name of itabirite...
Side 56 - The micaceous iron schist, or Itabirite, consists of alternating bands of varying thickness of micaceous iron ore and quartz, both these minerals and especially the quartz being often in a very friable condition, which accounts for its facility of weathering. The constituents of the schist exhibit a folded structure, and it has a special interest because it sometimes encloses thin lines of an ochreous mineral known as " Jacutinga " which often carries gold values.
Side 64 - The above list includes several of the largest known deposits, so that the contents of the others can not be estimated on a proportional basis, but it seems quite safe to assume for them at least an equal volume, which would double the above figures. In these estimates no account is taken of the presumed underground extension of the visible ore bodies. No attempt has been made...
Side 87 - The softer ore is heavily charged with hygroscopic moisture, and is responsible for the somewhat high percentage of water that the Miguel Burnier ores show in the rainy season. The metallic ore is exceptionally pure, the small quantity of metalloids being mostly concentrated in the softer mineral.
Side 57 - ... according as it is anhydrous and pure or hydrated and mixed with argillaceous matter. The rubble ore is always found on the surface, and varies between 1 and 10 yards in thickness. Owing to natural concentration, this rubble constitutes a very rich ore, averaging 66 to 70 per cent, metallic iron, whilst the conglomerate portion, which from its very nature is hydrated and mixed with argillaceous matter, contains a very much lower percentage of iron, varying according to the intermixture of binding...