The Goldschmidt System AS-A level Geology The Goldschmidt System Click anywhere on the screen to move on.

Chemistry of the Earth

Bulk composition comparable to Chondrites Chondrites are one of the stony meteorites, formed when various types of dust and small grains that were present in the early solar system accreted to form primitive asteroids Chondrites are the most common type of meteorite accounting for approximately 82% of all meteorites

The Goldschmidt Classification of Elements Swedish born mineralogist considered to be one of the founders of modern geochemistry and crystal chemistry Chemical elements on the periodic table are classified into groups according to their preferred host phases 4 groups are recognised: Lithophile, Siderophile, Chalcophile and Atmophile Victor Moritz Goldschmidt 1888 - 1947

The Goldschmidt Classification of Elements

Lithophile Elements - Concentrated in the Crust Lithophile (rock loving) elements are found close to the Earth’s surface as they combine readily with oxygen, forming compounds that do not sink into the core. The lithophile elements include: Aluminium Calcium Potassium Magnesium Sodium Oxygen Silicon Titanium

Elemental Composition of the Earth’s Crust 99% of the earth’s crust by weight is made up of just eight elements: Oxygen Silicon Aluminium Iron Calcium Sodium Potassium Magnesium

Lithophile Elements – Concentrated in the Crust Found in the silicate minerals which make up 93% of the crust by mass and constitute the common rock-forming minerals Quartz Orthoclase Feldspar Plagioclase Feldspar Biotite Mica Muscovite Mica Hornblende (Amphibole) Augite (Pyroxene) Olivine Garnet Clay Minerals (Kaolinite)

Siderophile Elements – Concentrated in the Core Siderophile (iron-loving) elements High density metals Tend to sink into the Earth’s core Do not combine with oxygen Dissolve readily in iron as solid solutions or in the molten state The siderophile elements include Gold Iridium Iron Molybdenum Nickel Platinum

Chalcophile Elements – Trace amounts in the Crust Chalcophile (ore-loving) elements Combine readily with sulphur Form compounds that do not sink to the core Make up just 0.046% of crust by mass (More concentrated in mineral veins) Chalcophile elements include Arsenic Cadmium Copper Lead Silver Sulphur Tin Zinc

Atmophile Elements – Concentrated in the Atmosphere and Hydrosphere Atmophile (atmosphere-loving) elements Also known as volatile elements Occur in gases and liquids close to the Earth’s surface The atmophile elements are Carbon Hydrogen Nitrogen Argon Helium Neon Krypton Xenon