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Gold mineralization in archaean cherts and iron-formations a review of the economic geology

  • Authors: Bellamy, R E S
  • Date: 1979
  • Subjects: Gold ores -- Geology -- South Africa , Gold mines and mining -- South Africa , Greenstone belts -- South Africa
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4968 , http://hdl.handle.net/10962/d1005580 , Gold ores -- Geology -- South Africa , Gold mines and mining -- South Africa , Greenstone belts -- South Africa
  • Description: The distribution of gold in igneous rocks and minerals is described and discussed. Not all the gold in igneous rocks is contained within early formed crystal lattices. Evidence that gold can be associated with late stage crystallizing phases is described. It is concluded that some of the gold in hydrothermal and volcanogenic deposits may have come from a primary magmatic source rather than having been leached from solid country rock. Gold is probably transported as chloride complexes at temperatures greater than about 300°C. At lower temperatures it is probably transported with other metals as sulphide and thio-sulphide complexes. The precipitation of gold from the transporting medium is brought about by changes in the physico-chemical conditions within that medium. Decrease in pressure is probably not a major cause of precipitation in volcanogenic environments. The geology of volcanogenic iron-formations is described and discussed, relative to the development of greenstone belts. Oxide facies iron-formations were formed in shallow oxidizing environments. They are associated with volcanogenic and clastic sediments. Sulphide facies iron-formations were precipitated in the deeper parts of geosynclinal structures. They are associated with mafic and ultramafic rocks similar to modern oceanic volcanic assemblages. Carbonate facies iron-formations were deposited in the regions between oxide facies and sulphide facies. Other banded iron-formations are found associated with base metal massive sulphide deposits related to arctype volcanic centres. These deposits are found in the regions where carbonate facies iron-formations were formed. Exploration for and exploitation of gold deposits in Archaean iron-formations are discussed. Geochemical exploration programmes are aided by the association of gold with trace amounts of base metals. Geophysical exploration methods that can be employed include magnetometer, I.P. and E.M. surveys. The metallurgical treatment of the ores should include "roasting" because a large proportion of the gold occurs as submicroscopic grains within sulphide mineral crystals.
  • Full Text:
  • Date Issued: 1979

Graaff-Reinet and the Great Depression (1929-1933)

  • Authors: Minnaar, Anthony de V
  • Date: 1979
  • Subjects: Graaff-Reinet (South Africa) -- History , South Africa -- Economic conditions -- 1918-1961
  • Language: English
  • Type: text , Thesis , Masters , MA
  • Identifier: vital:2518 , http://hdl.handle.net/10962/d1001847
  • Description: The Depression of 1929-1933 was a world-wide phenomenon, in which "no aspect of the economy, no part of the world, escaped devastation". ¹ Accordingly the study of a medium sized rural town in South Africa during the period of the Depression, should show effects and reactions that were, in general, indicative of worldwide trends. In choosing Graaff- Reinet, I felt that being a close-knit community , with its urban and rural populations closely associated with each other, and the white, coloured and black sections of the population interdependent, it adequately represented a microcosm of South Africa as a whole. Then, too, Graaff- Reinet was ideally suited to illustrate the reality, that in South Africa during the Depression " the farmers were the most heavily hit of all". ² The single most significant product of the Graaff- Reinet district was wool, which at the time of the Depression was South Africa's second most important export, and consequently the well-being of the whole district depended largely on the market performance of this product . During the Depression the price of wool dropped drastically and the Graaff-Reinet farmers suffered in consequence . Graaff-Reinet also went, almost according to a blueprint, through the general phases of the Depression. The privations of the farming community led to the financial embarrassment of the local financial institutions causing their collapse , which in its turn led to the widespread hardship of everyone in the town. But these events all had a particular Graaff-Reinet quality, and the twists to the general outline are rooted deep in the local character of the district . Historically Graaff-Reinet is extremely interesting. It is the fourth oldest town in South Africa, being established in 1786, and in studying Graaf-Reinet one cannot but become conscious of the immense tradition and the awareness of history , which all its people have. The study itself starts with a general outline of the Worldwide Depre ssion, its causes and results, then moves on to the Depression in South Africa . The study of Graaff-Reinet in the Depression is divided into three basic sections, the Farmers, the Townspeople, and the Politics of Graaff-Reinet during the Depression. All three contain their own sub-divisions dealing with different aspects. In the Graaff-Reinet sections are included references to national events, tying them to, and explaining the course of, local happenings. In short the study becomes the story of how the Depression effected the people of Graaff-Reinet, how they suffered during this period and how they reacted to it. A final concluding section deals with their general recovery from the Depression. ¹ Heaton, H. : Kruger, D. W. The Economic History of Europe. p. 696. ²The Making of a Nation; a history of the Union of South Africa 19l0 - 1960. p. 158.
  • Full Text:
  • Date Issued: 1979

Grahamstown Flats at the White Gate, Cradock Road, Burntkraal camp

Great Amen

Halalela

Hallelujah

Hallelujah

Hallelujah

Hallelujah

Hallelujah

Hallelujah

Hallelujah

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