Lesson CCXVI

Mica

Leading thought—Mica is a crystal which flakes off in thin scales parallel with the base of the crystal. We rarely see a complete mica crystal but simply the thin plates which have split off. The ordinary mica is light colored, but there is a black form.

Method—If it is not possible to obtain a mica crystal, get a thick piece of mica which the pupils may split off into layers.

Observations—1. Describe your piece of mica. Pull off a layer with the point of your knife. See if you can separate this layer into two layers or more.

2. Can you see through mica? Can you bend it? Does it break easily? What is the color of your specimen? What is its luster? Can you cut it with a knife? Can you scratch it with the thumb nail? What color is the streak left by scratching it with steel?

3. What are some of the uses of mica? How is it especially fitted for some uses?

4. Write a theme on how and where mica is obtained.