BACKGROUND:
A mineral is a crystalline, inorganic,
naturally
occurring combination of one or more elements. Observation is a key skill in
identifying minerals. This ability involves developing logical thought
processes. Learning minerals and mineral identification properties is very
difficult without hands-on activities, but is very easy when children can
explore and touch minerals. This lab helps students develop those skills.
Identifying minerals is important because minerals make up rocks.
The observational lesson prior to this lab can help
students use their senses to become familiar with the different minerals.
Some minerals like halite (salt) can be identified by their taste, while
others are identified by their hardness (quartz). The more students see and
feel minerals, the easier it is to remember them.
PROCEDURE:
- Demonstrate how to use a magnifying glass. The
students should hold the magnifying glass close to their face with one
hand, and then move the specimen back and forth with the other hand
until in comes into focus. Allow the students to experiment briefly,
looking at their hands or any other available objects.
- Explain to the students that today they will be
looking at minerals and trying to determine some of their
characteristics. Review the different characteristics that the students
may see when they examine the minerals. These properties include: color,
hardness, luster (glassy or metallic), crystal shape (see examples
below) or unusual properties (ulexite and calcite).
Students should examine each of the specimens.
They should use the magnifying glass to look at each specimen closely,
as well as their other senses. Stress with students that learning about
minerals includes both examining and thinking.
- As the students examine each specimen, they should
circle the characteristic that is most like the mineral in the workbook.
Review the correct answers after the students complete their lab. Use
the following information to help guide your remarks.
QUARTZ
is made up of silicon and oxygen. You might
want to point silicon and oxygen on the periodic characteristic is
that quartz is very hard. It is so hard that a steel knife cannot scratch
it.
GYPSUM is made of
calcium, sulfur and oxygen. Unlike quartz, it is very soft; a gypsum
crystal can be scratched by a fingernail. Gypsum is used in making plaster
board, which is used to make walls in houses.
MICA
has complicated crystal structure and a range of compositions, but, its main
components are aluminum, iron, silicon, and oxygen. Mica breaks in flakes.
Mica is fire proof. Ask students where they think mica could be used.
Examples include toasters, old time stoves, or fire proofing.
CALCITE is made up of
calcium, carbon, and oxygen. It is a very commonly used mineral in the
cement business. The calcite the students have will make an image appear
double when placed on top of it. This is because the way the molecules are
arranged.
ULEXITE
is made up of boron and oxygen. Ulexite crystals are fibrous (needle-like)
in shape. This gives the mineral a special property; for complex optical
reasons, images can travel along the fibrous crystals with little
distortion. For this reason, ulexite is often called "TV rock,"
although it is a mineral. Ulexite is used to make some detergents,
especially for washing clothes.
PYRITE
is commonly called "fool's gold," because many inexperienced
miners thought pyrite was gold. Pyrite is actually made of iron and
sulfur. Pyrite crystals have cubic shapes, and a brassy color. Real gold is
yellower than pyrite.
