Topic 1: ELEMENTS, MINERALS AND ROCKS Key Idea 1: The Earth is composed of rocks which have distinctive mineralogies and textures Knowledge and Geological techniques Comments understanding and skills a. The Candidates should be aware Earth’s elements may be classified of the four-fold classification according to the and its delineation and be Goldschmidt system able to name at least one (lithophile, element from each group. siderophile, chalcophile, lithophile: elements that atmophile) which aids combine well with oxygen subdivision of the and are concentrated in the Earth on the basis of crust; geochemistry siderophile: ‘iron loving’ (atmosphere, elements typical of the core; hydrosphere, crust, chalcophile: ‘ore loving’ mantle and core). elements which combine well with sulfur near the surface; Earth’s atmophile: volatile elements within liquids and gases on or above the surface. Earth’s b. The bulk composition Candidates should know that of the Earth is evidence for the internal comparable with that composition of the Earth of undifferentiated partly comes from chondrite meteorites meteorites. (chondrites). c. The crust is Recognition of the relative Candidates should know that Earth’s composed of eight abundance of O, Si, Al, Fe, 99% of the crust (by Earth’s main elements. Ca, Na, K and Mg in the crust weight) is made up of just 8 and the role of the silicates as elements and their relative rock-forming minerals. order of abundance.
Topic 1: ELEMENTS, MINERALS AND ROCKS Key Idea 1: The Earth is composed of rocks which have distinctive mineralogies and textures Knowledge and understanding Geological techniques and skills Comments a. The Earth’s elements may be classified according to the Goldschmidt system (lithophile, siderophile, chalcophile, atmophile) which aids subdivision of the Earth on the basis of geochemistry (atmosphere, hydrosphere, crust, mantle and core). Candidates should be aware of the four-fold classification and its delineation and be able to name at least one element from each group. lithophile: elements that combine well with oxygen and are concentrated in the crust; siderophile: ‘iron loving’ elements typical of the core; chalcophile: ‘ore loving’ elements which combine well with sulfur near the Earth’s surface; atmophile: volatile elements within liquids and gases on or above the Earth’s surface. b. The bulk composition of the Earth is comparable with that of undifferentiated meteorites (chondrites). Candidates should know that evidence for the internal composition of the Earth partly comes from chondrite meteorites. c. The Earth’s crust is composed of eight main elements. Recognition of the relative abundance of O, Si, Al, Fe, Ca, Na, K and Mg in the crust and the role of the silicates as rock-forming minerals. Candidates should know that 99% of the Earth’s crust (by weight) is made up of just 8 elements and their relative order of abundance.
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