2.2 A mineral is identified by its properties
way it breaks
Which better identifies a mineral, its luster or the way it breaks?
tests for color, luster,cleavage,fracture, and hardness would be easy. density,reaction acid, fluorescence and radioactivity would be more difficult to test for.
Which mineral-identification tests would be easy for a person to perform at home? Which would be difficult?
geologist
a scientist who studies the earth
streak
the color of a mineral's powder left behind when a mineral is scraped across a surface. - a method for classifying minerals
cleavage
the property of a mineral that describes its tendency to break along flat surface
luster
the property of a mineral that describes the way in which light reflects from its surface.
hardness
the resistance of a mineral or other mate, streak is the color of the powdered mineral.rial to being scratched
carbonate
What group of minerals react with hydrochloric acid?
they have the same streak
What is a clue that both samples are of the same mineral?
cleavage produces smooth flat surfaces and fracture produce irregular surfaces
What is the difference between cleavage and fracture?
They can occur in more than one color.
Why do you need to look at properties other than color to identify a mineral?
It is much more dense. A mineral's density is determined by the kinds of atoms that make up the mineral, as well as how closely the atoms are joined together.
Why does a piece of gold weigh much more than a piece of pyrite that is the same size?
denstiy
a property of matter representing the mass per unit volume
fracture
the tendency of a mineral to break into irregular pieces
the one with a hardness of 5 would be scratched, because the mineral with hardness of 7 is harder
Describe what would happen if you rubbed a mineral with a Mohs hardness value of 7 against a mineral with a value of 5
by comparing their hardness. harder minerals have stronger bonds
Diamond and graphite contain only carbon atoms. How can you tell which mineral's atoms are bonded more closely?
they glow when exposed to ultraviolet
How do minerals display fluorescence?
This scale is based on the fact that a harder mineral will scratch a softer one.
How do you use the Mohs scale to rank the hardness of an unknown mineral?
a mineral that has cleavage has weaker bonds in one or more directions. a mineral that fracture has bonds that are fairly equal in strength in all directions
How does the strength of the bonds between atoms determine whether a mineral displays cleavage or fracture?
a mineral can display both cleavage and fracture if its bonds are weaker in certain directions and are fairly equal strength
The mineral topaz has perfect cleavage in one direction. It also displays fracture. Explain why a mineral such as topaz can display both cleavage and fracture.
color
is a property of a whole mineral
streak
is the color of the powdered mineral.
metallic and nonmetallic
major types of luster