Special Mineral Properties

Unit Essential Question: How can we use the properties of a mineral to identify it?

Presentation Objectives: § Identify and describe unique properties that can make it easy to identify specific minerals.

Special Property 1: Smell and Taste

• Smell - Sulfur and Sphalerite • Smells like rotting eggs when...

• Sulfur is heated. • Sphalerite is sprinkled with

hydrochloric acid (HCl).

• Taste - Halite • Halite is NaCl, which is salt!

Do NOT lick the mineral samples!!

• Some minerals have a distinct smell or taste.

Special Property 2: Radioactivity• Some minerals contain radioactive elements.

• Most common are uranium and thorium.

• Use a Geiger counter to detect the energy released from these elements in the minerals.

Uraninite Thorianite

Special Property 3: Magnetism

• Magnetite is a mineral made out of iron. • It has magnetic properties which means it

attracts magnets or other metal objects.

Magnetite at the Smithsonian

Special Property 4: Double Refraction

• Calcite is a clear mineral. • When light passes through the mineral, it splits

into two and produces a double image.

Halite Calcite

Special Property 5: Reaction with HCl

• Calcite is also easily distinguished from halite because when dilute hydrochloric acid is placed on the mineral it bubbles and fizzes.

• This does not happen with halite. • It can happen with dolomite if powdered first.

Special Property 6: Fluorescence• Some minerals glow when placed under a UV light.

• They absorb the UV light and release it as visible.

Fluorite

Calcite

One More For Fun!• The mineral Ulexite is made from fibers that are

parallel and close together. • They act like fiber optic cables which transmit light

information from one place to another.

• Even though the mineral is translucent, the image from underneath is brought to the surface of the mineral.

Often referred to as the TV Stone!