ESS -- Notes –Fall 2010
Mineral: A natural, usually inorganic solid that has a characteristic chemical composition, an orderly internal
structure, and a characteristic set of physical properties.
4 Basic Questions to determine if a substance is a mineral:
(1) Is the substance inorganic?
(2) Does the substance occur naturally?
(3) Is it a solid crystalline form?
(4) Does it have a consistent chemical composition?
TO BE A MINERAL IT MUST ANSWER YES TO ALL THE QUESTIONS.
Group Activity – Mineral?
Ice
Sugar
Charcoal
Salt
Uranium
Y
N
N
Y
Y
Y
Y
N
Y
Y
Y
Y
N
Y
Y
Y
Y
N
Y
Y
ITEM
QUESTION
Inorganic?
Naturally Occurring?
Crystalline Solid?
Consistent Chemical
Composition?
Kinds of Minerals:
(1) Silicate –a mineral that contains a combination of silicon and oxygen and that may also contain one
or more metals.
Silicon – Si
Oxygen – O
Makes up 95% of the Earth’s Crust
INDICATED BY SiO
(2) Non- silicate= a mineral that does not contain compounds of silicon and oxygen.
Carbonates -- Chalk
Native elements – Silver, Copper
Oxides – Anything bonded with oxygen, Rust
Sulfates – anything bonded with SO4
Sulfides – Fool’s gold
Halides—Salts Ex. NaBr
Definitions:
Crystal: a solid whose atoms, or ions, or molecules are arranged in a regular, repeating pattern
Example: SALT
Silicon Oxygen Tetrahedron: the basic unit of the structure of silicate minerals; a silicon ion chemically bonded
to and surrounded by four oxygen ions
Example:
Mineralogists: Examines, analyzes, and classifies minerals.
Property
How it is identified
Inspect the minerals freshly exposed surface
Color
Unreliable !!!!
Streak
The color of mineral in powder form.
Luster
Light that is reflected from a minerals surface
Cleavage and Fracture
hardness
Rub the mineral against a tile called streak plate.
Ex. Chalk on chalkboard
Metallic – Polished Surface
Diamonds- Brilliant Luster
No-Luster – Dull/ Earthy
Ex. Waxy, Dull, Glossy, Glassy,
Cleavage – Tendency of a mineral to break along
specific planes.
Fracture – The manner in which a mineral breaks
along uneven, curved, or irregular surfaces.
Ability of a mineral to resist scratching
Mohs Hardness Scale
Mineral
Talc
Gypsum
Calcite
Fluorite
Apatite
Hardness
Common Test
Mineral
Hardness
1
Easily Scratched by
fingernail
Feldspar
6
Quartz
7
Easily Scratches glass
and Steel
Topaz
8
Scratches Quartz
4
Corundum
9
Scratches Topaz
5
Diamond
10
Scratches Everything.
2
3
Barely Scratch by
copper penny
Common Test
ESS -- Notes –Fall 2010
Fluorescence and
Phosphorescence
Fluorescence – The ability of a mineral to glow under UV (Ultraviolet) light. Ex: Cosmic Bowling
Phosphorescence—The ability of a mineral to still glow after being exposed to UV light. Ex. Glow In the Dark Stars.
Chatoyancy – Some minerals display a silky material. Result of closely packed fibers in the mineral.
Chatoyancy and
Asterism
Double Refraction
Magnetism
Radioactivity
Asterism – *** The star shaped reflection off of a crystal. Ex. Diamonds
Double Refraction is when something is reflected twice
The ability of a mineral to attract iron based materials. Ex. Magnet
The releasing of energy through the decaying of nuclei. Ex. Geiger Counter
Density = MASS/ VOLUME = Ex. A marble has the same amount of mass as a marshmallow but they have different
volumes. The marble is much smaller so it is more dense. The marshmallow is larger so it is less dense.