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Questions and Answers
What are Major and Minor elements?
What are Major and Minor elements?
Major elements are usually greater than 1%, while Minor elements are usually 0.1 - 1%.
How is whole rock geochemical analysis obtained?
How is whole rock geochemical analysis obtained?
By crushing, pulverizing, and grinding a representative sample followed by spectroscopic analysis.
Which of the following represents analytical methods used in whole rock geochemistry?
Which of the following represents analytical methods used in whole rock geochemistry?
What is the significance of trace elements in rock analysis?
What is the significance of trace elements in rock analysis?
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Major elements constitute the main constituents of rock-forming minerals.
Major elements constitute the main constituents of rock-forming minerals.
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What does LOI stand for in geochemical analysis?
What does LOI stand for in geochemical analysis?
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Which elements are considered as major elements in geochemistry?
Which elements are considered as major elements in geochemistry?
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Trace elements are usually present in concentrations less than ______ wt%.
Trace elements are usually present in concentrations less than ______ wt%.
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What does the total iron in rock analysis signify?
What does the total iron in rock analysis signify?
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Study Notes
Major and Minor Elements
- The major elements in the Earth's crust are oxygen, silicon, aluminum, iron, calcium, magnesium, sodium, and potassium. These occur in weight percentages greater than 1%.
- Minor elements occur in concentrations between 0.1% and 1%.
- Trace elements are categorized as those that are less than 0.1% in weight.
Whole Rock Geochemistry
- Whole rock chemical analysis involves crushing, pulverizing and grinding a representative sample rock, and then analyzing the powder or dissolved portion.
- Analytical methods used include: XRF (X-ray Fluorescence), ICP-MS (Inductively Coupled Plasma Mass spectrometry), and INAA (Instrumental Neutron Activation Analysis).
- Results are presented as weight percentages for major and minor elements, and parts per million (ppm) or parts per billion (ppb) for trace elements.
- Major and minor element concentrations are typically expressed as oxide weight percentages.
- Total iron is determined and expressed as FeOTot or Fe2O3Tot.
- Fe2O3 can be converted to FeO by multiplying by 0.8998. FeO can be converted to Fe2O3 by multiplying by 1.1113.
- Trace elements provide crucial information about the petrogenetic processes involved in a rock's formation.
- Volatiles, such as H2O, CO2, and S, are analyzed separately and can be determined through the LOI (loss on ignition), which measures the total volatile content.
Analytical Results
- Volatiles are discriminated from major elements.
- H2O can be classified as H2O+ and H2O-.
- LOI (loss on ignition) is the most common way to present volatile content in rock analysis.
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Description
Explore the major and minor elements found in the Earth's crust, and delve into whole rock geochemistry techniques. This quiz covers the analytical methods used for chemical analysis and the representation of results for various element concentrations. Test your knowledge on the crucial concepts of geochemistry and analytical techniques.
