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GIA J UNIOR GEMOLOGIS T
Boy SPcouts
of Ame rica
ROGRAM™
Me rit Ba dge S e rie s : Ge ology


GEOLOGY AND GEMS

Geology is the science and study of the Earth,
its composition, structure, physical properties,
history, and the processes that shape it.


WHAT IS ROCK?

• A rock is a solid material made up of minerals
• Rocks are the building blocks that make up the earth
• Rocks tell a story about the earth and how it was formed


IGNEOUS ROCK

Eruption of Mount St. Helens volcano,1980

Pumice

Igne ous rocks s ta rt out in a molte n or s e mi-molte n s ta te a nd
be come s olid whe n the y cool.

IGNEOUS ROCK FORMATION

extrusiv
e
intrus
ive


IGNEOUS ROCKS

Granite

Lava


S EDIMENTARY ROCK

Sandstone

S e dime nta ry rocks a re forme d by la ye rs of s e dime nts s que e ze d
a nd pre s s e d toge the r ove r a long pe riod of time .


METAMORPHIC ROCK

CONVICT LAKE, CALIFORNIA

Slate

Me ta morphic rocks ha ve the ir

ma ke up, te xture , or s tructure cha nge d
by gre a t he a t, pre s s ure , or both.


METAMORPHIC
MOUNT CHO OYU, NEPAL (26,906 ft.)

Marble with spinel


DEFORMATION OF ROCKS
•

Rocks are continually being subjected
to forces that bend them.

•

A fold can be defined as a bend in rock
that is the response to compressional
forces.

•

Folds are most visible in rocks that
contain layering.


ROCK ACTIVITY

CAREERS IN GEOLOGY
•

What is someone called who studies
geology?
 A geologist

•

What does a geologist do?
 They work to understand the
history of our planet so that they
can foresee how past events
might influence the future.


ADVANCED CAREERS IN GEOLOGY

Pa

y
g
o
ol
t
n
leo

y

g
o
ol
r
d
Hy


MINERALOGY

Mine ra logy is the s cie nce tha t involve s the
che mis try, crys ta l s tructure , a nd phys ica l
(including optica l) prope rtie s of mine ra ls a nd
the proce s s e s tha t cre a te the m.


MINERALS
To be considered a mineral a material must
have all of the following features:
• Solid
• Inorganic
• Formed in Nature
• Specific Chemical Composition
• Crystal Structure


IDENTIFICATION OF MINERALS
CRYS TAL S TRUCTURE

CRYS TAL S TRUCTURE
The most exciting aspects of minerals are
their beautiful and elegant crystal forms.
A mineral’s crystal form is an exterior
expression of what is happening on the
inside of a mineral at the atomic level.


CRYSTAL STRUCTURE
ACTIVITY


Harde r

MOHS HARDNES S S CALE

S o fte r

140x

124,000x
10 9 8 7 6 5 4 3 2 1

10. Diamond
9. Corundum (Sapphire/Ruby)
Topaz
8. Quartz
7. Orthoclase feldspar
6. Apatite
5. Fluorite

4. Calcite
Gypsum
3. Talc
2.
1.


IDENTIFICATION OF MINERALS
HOW DO MINERALS GET THEIR COLOR?
•

What color is sunlight/white light?
 All the colors in a rainbow

•

When light hits an object, some of the
colors get absorbed

•

Other colors reflect within the object and
transmit back to our eyes

•

This is the color we see


COLOR ACTIVITY

IDENTIFICATION OF MINERALS
STREAK
• Streak testing is a method used in
mineral identification
• Helps distinguish gold (yellow
streak) from pyrite (black streak)
• Streak testing is destructive and
not recommended


IDENTIFICATION OF MINERALS
LUSTER
Luster is a way that light interacts with the surface of a
material
• High-luster Categories
 Adamantine - diamond like
 Metallic
• Medium-luster Categories
 Vitreous - glass like
•

Low-luster Categories
 Waxy – Dim and blurred like the surface of a
candle


LUSTER ACTIVITY

GEMOLOGY
Ge mology is the s cie nce ,
a rt a nd profe s s ion of
ide ntifying a nd e va lua ting
ge ms tone s . It ma y be
cons ide re d a bra nch of
mine ra logy.