How do you use the streckeisen (QAPF) classification ternary …
Dec 19, 2017 · The QAPF and related diagrams are intended for classification of rocks in the field, or preliminary classification with modal proportions as seen in the optical microscope. They are not designed with the chemical composition of the rocks in the mind. Furthermore, these diagrams are merely descriptive and not genetic.
Why don't pyroxenites and peridotites appear in Streckeisen's …
QAPF diagrams are also not used if mafic minerals make up more than 90% of the rock composition (for example: peridotites and pyroxenites). Instead, we use a different diagram, that has olivine, orthopyroxene, and clinopyroxene at the vertices.
On QAPF (Steckeisen) diagrams, should Albite be considered on …
Aug 18, 2022 · QAPF diagrams are double ternary diagrams used for magmatic rock classification based on mineralogy. Quartz and Feldspathoids are opposed on the pointy ends of the diamond, with Alkali feldspar and Plagioclase (feldspar) on the intermediary vertex.
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Wikipedia says for QAPF diagrams: "A QAPF diagram is a double ternary diagram which is used to classify ...
The different types of plagioclase - Earth Science Stack Exchange
Jan 23, 2015 · Consider the following diagram below - the relevent part for your question is across the base of the triangle: Image source . For example, oligoclase is An 10%-30% means that it would possess a $\ce{Ca^{2+}}$ mole percent of between 10% to 30%, and a corresponding $\ce{Na+}$ mole percent of between 70% to 90%.
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Jul 13, 2020 · Stack Exchange Network. Stack Exchange network consists of 183 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.
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Aug 23, 2020 · Stack Exchange Network. Stack Exchange network consists of 183 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.
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Dec 10, 2016 · Stack Exchange Network. Stack Exchange network consists of 183 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.
Newest 'petrology' Questions - Earth Science Stack Exchange
Stack Exchange Network. Stack Exchange network consists of 183 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.
How are spherulitic structures formed in basalt rock?
Oct 25, 2014 · 8. After having studied the thin sections of basalt under the microscope, I have come across many spherulitic structures occurring in clusters. How can this happen? Is it due to devitrification or is it something else? What is the natural process behind formation of such structures? Image for reference: geology. mineralogy.