MineralsMineralsCH 2 Prentice Hall
p. 47-54CH 2 Prentice Hall
p. 47-54
What is a Mineral?• A naturally occurring,
inorganic solid that has a crystal structure and definite chemical composition.– Over 3,000– 20 minerals form
Earth’s crust.• Rock forming minerals.
Naturally Occurring
• Must form through Earth’s processes.– Cement, Brick, Steel
and Glass all come from substances in Earth’s crust.
– But they are manufactured by people.
• Cannot come from materials that were once part of living things.– Coal- forms naturally,
comes from the remains of plants and animals.
Inorganic
• Always solid, with a definite volume and shape.– Particles can’t flow
freely.
Solid
Crystal Structure• Particles of a mineral line up in a repeating
pattern. Forms a solid called a crystal.– Has flat sides called faces, that meet at sharp
edges and corners.
• A mineral always contains certain elements in definite proportions.
• Element- a substance composed of a single kind of atom.– All atoms have the same chemical and physical
properties.
Definite Chemical Composition
• Compound- Two or more elements combined.– Most minerals are compounds.– Chemically joined.
Definite Chemical Composition
Definite Chemical Composition
• Mixture- consists of two or more substances that are mixed together but not chemically combined.
Crystal Structure
• Each mineral grows atom to atom to form that mineral’s particular structure.– Classified into six groups (crystal systems) based
on the number and angle of the crystal faces.
Identifying Minerals
Identifying Minerals
Crystal Systems
Cleavage/Fracture
Special Properties
Density
Hardness
Color
Streak
Luster
Color
• 1. Color is an easily observed physical property. Not the best property to use to identify because many minerals like quartz can come in a variety of colors.
Identifying Minerals
Streak
• Streak is the color of the minerals powder when it is rubbed against a Streak Plate – This property does not vary like the color of
the mineral can.
Identifying Minerals
Luster
• Metallic luster- looks like a metal.
• Non-Metallic Luster- does not look like a metal, can be glassy, dull, earthy, waxy and pearly.
• Luster is used to describe how a mineral reflects light from its surface.
Identifying Minerals
Crystal Structure
• Each mineral grows atom to atom to form that mineral’s particular structure.– Classified into six groups (crystal systems) based
on the number and angle of the crystal faces.
Identifying Minerals
Crystal Structure• Particles of a mineral line up in a repeating
pattern. Forms a solid called a crystal.– Has flat sides called faces, that meet at sharp
edges and corners.
5. Cleavage
• Cleavage- is a mineral that easily splits along flat surfaces.
Identifying Minerals
6 Fracture
• Fracture- describes how a mineral looks when it breaks apart in an irregular way.
Identifying Minerals
Special Properties
• Fluorescence- glows under UV (ultraviolet light)
• Magnetic- acts like a magnet• Radioactive- give off radiation- Uraninite• Reacts to Acid- reacts by fizzing.• Electrical Properties- electric current can be
produced (Quartz)– Used in watches
Identifying Minerals
• The resistance to being scratched. One of the best clues.• Mohs hardness scale.
– A scale from 1 to 10.
Hardness
Identifying Minerals
ss
Mohs Hardness Scale see p150 to label boxes with minerals
Hardest known mineral, Diamond can scratch all
other surfaces.Identifying Minerals
• It is the mass in a given volume.
• It always remains the same for any given mineral.
Density
Identifying Minerals
• A balance would be used to measure the mass of a sample.
• The sample can be placed in a graduated cylinder to determine the volume.
Density
Identifying Minerals
• Water Displacement (how much water is moved, is equal to the volume of the sample) is used to determine the volume of the sample
Density
Identifying Minerals