**BACKGROUND:**
The shape of a mineral crystal reflects the arrangement of atoms which
compose it. The nature of this arrangement is affected by the size of
the atoms and how they bond together. Mineral breakage is also
determined by atomic arrangement; some minerals cleave along weak planes
in the atomic structure.

It is important for students to be able to recognize geometric shapes
in minerals. Many times geometry and science are taught independently.
Therefore, students sometimes do not realize that geometry is a
mathematical (or quantitative) way of describing the real world. For
example, the shapes of mineral crystals and the mineral cleavage may be
described by geometric terms. However, note that real mineral crystals rarely occur as perfect geometric forms.

**
**Shapes help us recognize objects. Mathematicians give names to
very specific shapes. This exercise teaches students four common shapes
that are commonly seen in minerals.

**PROCEDURE:**

- Draw the three geometric shapes on the board. Ask
the students to identify them. Illustrate the difference between a
square and a cube and between a rectangle and a rhombohedron. Use
geometric models if you have them available

- Have students practice drawing the shapes.

- Give the students a copy of the quartz crystal
model. After they cut it out, make sure the students fold each line
before they glue it together. It will make assembly much easier. You may
wish to have them color the model before assembling it.