Looking at the Rock Cycle Through Pottery

1. Looking at the Rock Cycle Through Pottery

2. Review Questions: • What is a rock? • What is a mineral? • How do igneous rocks form? • How do sedimentary rocks form? • How do metamorphic rocks form?

3. Mineral Soil Types • What is sand? Made primarily of quartz (SiO2) Defined by a relatively LARGE particle size of 2mm-0.062mm • What is silt? Mineral soil Defined by a MEDIUM particle size 0.062mm-0.0039mm • What is Clay? Particle size is SMALL; less than 0.0039mm Most clay is made of silicon tetrahedrons that are glued together with Fe, Na, K or water Outer layer has a negative net charge; thus attracts a lot of positive cations like K and N

5. Clay Particles Magnified under an Electron Microscope If a grain of sand were the size of a basketball, then a piece of silt would be the size of a marble, and a particle of clay would be a pinpoint. Clay particles are tiny, less than one 12,500th of an inch.

6. Why is red clay red? • Why is blue clay blue?

7. Behind the Pottery Fall 2005

8. A clay filled tobacco field 10 miles from the Jones Pottery

15. Does clay fired in kilns transform into an igneous rock or a metamorphic rock? How can we answer this question? What information do we need? Top temperature of the kiln is 1260° C (2300° F) Partial melting begins at 800° C (1472° F)

17. What is a primary ingredient in the glazes that coat the outside of pots? • Think about how the outside of glazed pots compares to the outside of unglazed pots • Watch what happens to glazes and GLASS during video. • glass = Na (a flux) + SiO2

18. Pottery and the rock cycle The clay particles that are fired undergo a metamorphism. Under intense heat, they partially melt and form something else altogether. Glazes that are painted on the pot completely melt. They are made largely of glass, so they are lowest on Bowen’s Reaction series and melt most easily.

19. The Firing