Handbook of Nature-Study · Lesson CCXIV · Topic 33: Crystals, minerals and rocks
214. Quartz
Goal: Your child can recognize quartz by its six-sided crystals, glassy luster and hardness, and knows some of its kinds.
You'll need
- Quartz: a clear crystal if possible, plus any of amethyst, rose quartz, smoky quartz, agate or flint
- A steel nail
- A small piece of plain glass with smoothed edges (a glass tile) set on a folded towel
- Safety glasses
- A hand lens (magnifying glass)
- A nature notebook and a pencil (colored pencils if you have them)
What's in the book
The lesson has a leading thought, a method asking for several kinds of quartz, and five observations on the crystal's shape, its luster, its hardness against a knife and glass, its kinds and uses, and petrified wood.
The lesson, step by step
The leading thought
Quartz is one of the most common of minerals. It occurs in many forms. As a crystal it is six-sided, and the ends terminate in a six-sided pyramid. It is very hard and will scratch and cut glass.
The crystal
What is the shape of quartz crystals? Are the sides all of the same size? Has the pyramid-shaped end the same number of plane surfaces as the sides?
The luster
What is the luster of quartz? Is this luster the same in all the different colored kinds of quartz?
Hardness
Can you scratch quartz with the point of a knife? Can you scratch glass with a corner or piece of the quartz?
Use a steel nail instead of a knife. For the glass test, an adult holds the glass tile flat on a towel while your child draws one short line with a quartz point. Wear safety glasses, and rub away any glass dust with a damp paper towel.
Kinds of quartz
Describe the following kinds of quartz and their uses: amethyst, agate, flint.
What has quartz to do with the petrified forests of Arizona?
Look for it
Look through your pebble collection and at sand with the lens. Glassy, white or clear grains that the nail can't scratch are probably quartz.
Nature notebook
Draw a quartz crystal: six sides and a six-sided point. Add a row for quartz in your mineral chart.
Answers to the book's problems
Six sides with a six-faced pyramid point; the sides are often unequal in width. Glassy luster in all its colors. A knife or nail cannot scratch quartz, but quartz scratches glass (hardness 7). Amethyst is purple quartz, used as a gem; agate is banded quartz, used for jewelry and polished stones; flint breaks with sharp edges and was used for tools and to strike sparks. In the petrified forests, quartz slowly filled and replaced the wood of buried logs, turning them to stone.
Worked out for this site from the scan. If a number in your copy differs, trust the book.