Transcript Diapositiva 1 - Liceo Galvani

Minerals are not made
by people; they are …
…naturally occurring substances.
Minerals
•
•
•
•
Natural
Solid
Inorganic
Definite chemical
composition
• Crystal structure
due to internal
arrangement of
atoms
http://www.minerals.net/gemstone/index.htm
Physical Properties of Minerals
(can be used to identify the mineral)
Color
• Can be misleading
• Can vary with the type of impurities
Physical Properties of Minerals
(can be used to identify the mineral)
Luster
• Surface reflection
• metallic = shiny like
metal
• non-metallic = dull,
non-shiny surface
Pyrite has a metallic luster
Calcite has a non-metallic luster
Physical Properties of Minerals
(can be used to identify the mineral)
Hardness
• How easily a mineral scratches
materials
• Mohs Hardness Scale
• Scale from 1 (softest) to 10 (hardest)
• Test by seeing if the mineral can scratch
different objects (like human fingernail, copper,
penny, glass, steel file)
Sfaldatura
(Cleavage)
Tendenza a rompersi lungo piani
paralleli alle facce dell’abito
cristallino. Determinata dal reticolo
Cleavage & Fracture
– The way the mineral breaks
– Cleavage—minerals break
along smooth, flat surfaces
and every fragment has the
same general shape
– Fracture—minerals that break
at random with rough or
jagged edges
Streak
• The color of the
powdered form of the
mineral
• The color of the streak
can be different than the
mineral
• Minerals must be softer
than the streak plate
Streak…can help identify quartz
http://www.childrensmuseum.org/geomysteries/cube/b3.html
Groups of Minerals
• Minerals are grouped by the elements
they are made of.
Beryl (Emerald)
Calcite
Amethyst
Mineral Group Characteristics
Non-Silicates
Silver
•Make up only
5% of the
Earth’s crust
•Include some
of the most
important
minerals
Examples
iron, copper,
gold, silver,
diamonds,
rubies
Copper
Diamond
Gold
Ruby
Iron
Mineral Group Characteristics
Carbonates
Examples
•Carbon &
Calcite (CaCO3)
oxygen and a
positive ion,
such as calcium
Calcite with Duftite inclusions
Mineral Group Characteristics
Oxides
Metallic ion
and oxygen
Examples
Hematite
(Fe2)O3
Mineral Group Characteristics
Sulfides
Sulfur and a
metallic ion
Examples
Galena (PbS)
Mineral Group Characteristics
Sulfates
Barite on Calcite
BaSo4 / CaCO3
Metallic ion,
Sulfur &
oxygen
Barite
BaSo4
Examples
Barite (BaSO4)
Mineral Group Characteristics
Native
Elements
Single
elements
Examples
Gold (Au),
Diamond (C),
Silver (Ag)
Mineral Group Characteristics
Silicates
Examples
•Contain oxygen Quartz, mica
& silica
•The most
abundant group
of minerals
MICA
Quartz
Special Characteristics
the “Acid Test”
Carbonates react
with dilute HCl and
other acids by
fizzing or bubbling
(releasing CO2 gas)
Special Characteristics
Fluorescence
• Some minerals will
glow when placed
under short-wave or
long-wave ultraviolet
rays
http://www.sterlinghill.org/Tour%20information.htm
Special Characteristics
Salty Taste
• DO NOT TASTE
MOST MINERALS!
http://mineral.galleries.com/scripts/item.exe?LIST+Minerals+Halides+Halite
Special Characteristics
Magnetism
• Many iron minerals
will produce an
invisible magnetic
force field
http://www.minerals.net/mineral/oxides/magnetit/magneti4.htm
What do all minerals have in
common?
All:
1.
2.
3.
4.
Are formed by natural processes.
Are NOT alive and NEVER were alive
Have a definite volume and shape
Are elements or compounds with a unique
chemical makeup
5. Are made up of particles that are arranged in
a pattern that is repeated over and over
(called a CRYSTAL)
How do minerals form?
• 1) Cooling of magma (hot, liquid rock and
minerals inside the earth (from the
mantle))
– Fast Cooling = No Crystals (mineraloids)
– Medium Cooling = small crystals
– Slow Cooling = large crystals
How do minerals form?
• 2) Elements dissolved in liquids (usually
water)
1.What element are diamonds made from?
2. What do all crystals have in common?
Cleavage or Fracture?
1.
4.
2.
3.
1. If a mineral can scratch your fingernail,
the mineral is _______________ than
your fingernail.
2. What is luster?
Review