Rocks & Minerals

{Rocks & Minerals

Miss Napolitano & Mrs. RodriguezEnvironmental Science

Minerals combine to make rocks!

Minerals: naturally occurring, inorganic, solid compounds with a definite crystalline structure & chemical composition

Rocks: Solid mass composed of a combination of minerals or organic compounds

Rocks vs. Minerals

Produced by nature Solid Organic compounds (contain C & H) &

are NOT produced by organic processes

Have a definite crystalline structure Have a definite chemical formula

What makes a mineral?

Halite - NaCl

For every atom of Sodium there is an atom of Chlorine.

Diamond Teeth Kidney stones Gold Pearls Clay Zinc Amber Sea shells Mica

Mineral or Not?

Diamond – Mineral! Teeth – Not! Kidney stones – Not! Gold – Mineral! Pearls – Not! Clay – Mineral! Zinc – Mineral! Amber – Not! Sea shells – Not! Mica – Mineral!

Mineral or Not?

Minerals can be classified in the following ways: Hardness Cleavage/Fracture Streak Luster Color Specific Gravity Taste Magnetism Light Chemical Properties

Mineral Classification

Resistance a mineral has to being scratched

Minerals are scratched against one another The one that has scratch marks is the

softer mineral

Use Moh’s Scale of Mineral Hardness as a guide!

Hardness

Cleavage: the tendency of a mineral to break along smooth planes

Fracture: the tendency of a mineral to break along curved planes

Think: like tearing paper along perforations

Cleavage/Fracture

Streak: the color of the mineral in powder form

Mineral is rubbed across a streak plate (porcelain) Streak plate hardness = ~7

Some minerals have surprising streak colors!

Streak

Luster: the quality of reflected light

Classified as either metallic or non-metallic

Luster

Easiest to notice but not always reliable!

The picture shows different versions of calcite:

Color

Specific Gravity: mineral density

Weighed in air, then weighed in water

Specific Gravity

DO NOT PERFORM A TASTE TEST ON ANY UKNOWN MINERALS – SOME ARE TOXIC!!

But, some minerals have unique tastes

Taste

Magnetism: the ability of a mineral to be attracted by a magnet

Usually indicates if a mineral has a high concentration of iron

Magnetism

Minerals are classified as opaque, translucent, or transparent

Opaque: no light passes through

Translucent: some light passes through

Transparent: you can see through the mineral

Light

Transparent minerals can also display double refraction – beams of light separate to display a double image

Light – Double Refraction

Minerals can display certain chemical properties, such as reaction with acid or reaction with ice

Chemical Properties

Use this time to take Cornell Notes on classifying minerals! (~5 minutes)

Take out a piece of paper & fold in half (hot dog) – 1 side can be bigger than the other

On smaller side: write main ideas On larger side: write supporting

details Write down any questions at the

bottom/on the back of your paper!

Brain Break – Cornell Notes

Rocks are classified by how they are formed

3 main types of rocks: Igneous Sedimentary Metamorphic

Rocks

Cooled magma from the mantle

BTW: magma = underground, lava = aboveground

Ex: granite

Igneous Rocks

Composed of pre-existing rocks

General characteristic = stratification (layering) Due to weathering & erosion

Ex: limestone, coal, gypsum

Sedimentary Rocks

Rocks that have changed form due to heat, pressure, or fluids

Done without melting

Ex: slate

Metamorphic

Rocks can change from one form to another!

The Rock Cycle