Minerals. Definition: A mineral is naturally occurring Made by Mother Nature -it is NOT man made!
-
Upload
oscar-townsend -
Category
Documents
-
view
218 -
download
1
Transcript of Minerals. Definition: A mineral is naturally occurring Made by Mother Nature -it is NOT man made!
Minerals
Definition: A mineral is
• naturally occurring
Made by Mother Nature
-it is NOT man made!
• An inorganic material
(It is NOT and has
NEVER been living)
It is NOT a liquid
It is NOT a gas
It is a SOLID
It has a crystalline structure when examined under a microscope
It has either a • cubic
• hexagonal• orthorhombic
• monoclinic• triclinic
or• tetragonal
Crystalline Structure
It has a definite chemical composition
• Every atom of the mineral has the same chemical formula
• For example: Halite: NaCl Galena: PbS
Fluorite: CaF2
Talc: Mg3Si4O10(OH)2
A mineral is:
• naturally occurring
• inorganic
• solid
• crystalline structure
• chemical composition
• Now
• I
• See
• Crystal
• Clear.
Classification of minerals
HARDNESS
• Geologists use the Mohs Hardness Scale to determine a mineral’s hardness.
• The Mohs Hardness Scale ranks a mineral’s hardness from 1-10 with 1 being the softest ( can scratch it with your fingernail) and 10 being the hardest (cannot be scratched by any other substance).
• The mineral with a Mohs Hardness Scale of 1 is talc.• The mineral with a Mohs Hardness Scale of 10 is
diamond.
Color
• Color is a physical property of a mineral.
• It is NOT a dependable way to classify minerals because many minerals may have the same color.
Examples:• Gold and pyrite are both gold.• Quartz may be rosy pink, white, purple, gray or
yellowy.
Streak
• A mineral’s streak is the color it leaves behind when scratched on an unglazed tile called a streak plate.
• A mineral’s streak is the color of its powder.
Luster
• A mineral’s luster describes how the mineral reflects light.
Examples:
• Minerals that are metals are shiny.
• Quartz has a glassy luster.
• Talc has a greasy luster.
Density
• Each mineral has its own characteristic density. That is why density is an excellent way to identify a mineral.
• Density refers to a mineral’s mass per unit of volume.• Geologists use a balance to determine a mineral’s mass
and water displacement with a graduated cylinder to determine its volume.
• Density is expressed in units called grams per cubic centimeter.
• The formula for calculating the density of a mineral (or any substance) is its mass divided by its volume.
Cleavage and Fracture• Cleavage refers to a mineral’s ability to
split along flat surfaces. (String cheese has cleavage along a regular surface.)
• Fracture refers to a mineral’s ability to break along irregular surfaces. (Tearing a piece of paper is an example of what this looks like.)
Special Properties
• Some minerals have magnetic properties. That means that they are attracted to magnets.
• Some minerals are fluorescent. That means that they glow under ultra violet (UV) light.
• Some minerals are radioactive. They cause a Geiger counter to be set off.
• Other minerals have electrical properties. Quartz produces a slight electrical current when pressure is applied to it.