What is Feldspar?
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What is Feldspar?

Feldspar Quarry
A feldspar quarry in India

October 2016 - Feldspar is a very common igneous rock - more than half of the Earth's crust is made of feldspar. When molecules of aluminum, silica and oxygen get together with potassium, they combine to make the rock feldspar.


Feldspar often combines with another rock called quartz to make a much harder igneous rock called granite. Or, if feldspar gets in contact with another rock called pyroxene, those two rocks combine to make basalt.

When feldspar is in contact with wind or water, the wind and water gradually grind the feldspar down into tiny grains that become one kind of clay called kaolin. Kaolin is the extremely fine, white clay that Chinese porcelain is made of.

Learn by doing: finding different kinds of rocks
More about granite
More about basalt
More about igneous rocks

Bibliography and further reading about rocks:

More about igneous rocks
More about volcanoes
More about geology
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Professor Carr

Karen Eva Carr, PhD.
Assoc. Professor Emerita, History
Portland State University

Professor Carr holds a B.A. with high honors from Cornell University in classics and archaeology, and her M.A. and PhD. from the University of Michigan in Classical Art and Archaeology. She has excavated in Scotland, Cyprus, Greece, Israel, and Tunisia, and she has been teaching history to university students for a very long time.

Professor Carr's PSU page

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