Minerals, Rocks, and Rock Forming Processes · Minerals • Because of their abundance, oxygen and...
Transcript of Minerals, Rocks, and Rock Forming Processes · Minerals • Because of their abundance, oxygen and...
Energy and Matter
Pho
to b
y S
penc
er B
lack
[http
://itc
olos
sal.c
om/n
atio
nal-g
eogr
aphi
c-se
ptem
ber-
2013
]
Minerals, Rocks, and Rock Forming Processes
What is the Earth’s crust made of?
Composition of our Earth
• Of the __ naturally occurring chemical elements, only __ occur in Earth’s crust
• The crust is dominated by two elements – ________ – ________
How does this compare to the elements in our bodies?
Minerals
• Minerals are the building blocks of the geosphere, they are or have: – Naturally formed – Inorganic – Solid – Specific chemical composition – Characteristic crystal structure
MineralsThe two characteristics that best allow the study of minerals are
1. Crystal structure: the way the atoms of the elements are packed together
2. Composition: the major chemical elements that are present and their proportions
Minerals
• Because of their abundance, oxygen and silicon form the basis for the most common rock-forming minerals, and the most common mineral group: silicates
• Other mineral groups include: oxides, sulfides, carbonates, sulfates, and phosphates
Minerals
• Silicates are by far the most abundant minerals in the continental crust, and feldspars are the predominant variety – Feldspars: 60% of minerals in Earth’s crust – Quartz: 15% of minerals in Earth’s crust – All silicates: 95% of minerals in the crust
• This limits non-silicates to only 5% of the Earth’s crust!
Minerals
• Density and specific gravity – Specific gravity is easier to measure, and
therefore more commonly used – It is the ratio of the weight of the substance
to the weight of an equal volume of pure water
– The densities of some minerals are distinctive; such as gold and galena
Let’s work on this
DENSITY AND
SPECIFIC GRAVITY
Some Specific Gravity MeasurementsMaterial Specific Gravity Balsa wood 0.2 Oak wood 0.75 Ethanol 0.78 Water 1 Table salt 2.17 Aluminium 2.7 Cement 3.15 Iron 7.87 Copper 8.96 Lead 11.35 Mercury 13.56 Depleted uranium 19.1 Gold 19.3 Osmium 22.59
Rocks
• A rock is any naturally formed, nonliving, coherent aggregate mass of solid matter that constitutes part of a planet, asteroid, moon, or other planetary object
• Minerals are the most common and abundant building blocks of rocks
14
Rocks
16
17
Rocks• Earth’s crust is mainly igneous and
metamorphic rock, however, most of the rock we see at surface is sedimentary
Rocks
• The two main features that best classify rocks are – Texture: the overall appearance of a rock,
resulting from the size, shape, and arrangement of its mineral grains
– Mineral assemblage: the kinds and relative amounts of minerals present
Taos Rocks! !
!
!
!
!
3 examples of each rock type
IGNEOUS ROCK: BASALT
IGNEOUS ROCK: BASALT
IGNEOUS ROCK: BASALT
IGNEOUS ROCK: BASALT!~ 4 million years ago
SEDIMENTARY ROCK: SHALE
SEDIMENTARY ROCK: SHALE
SEDIMENTARY ROCK: SHALE
SEDIMENTARY ROCK: SHALE
SEDIMENTARY ROCK: SHALE!~ 300 million years ago
SEDIMENTARY ROCK: SHALE!~ 300 million years ago
METAMORPHIC ROCK: GARNET SCHIST
METAMORPHIC ROCK: GARNET SCHIST
METAMORPHIC ROCK: GARNET SCHIST
METAMORPHIC ROCK: GARNET SCHIST
METAMORPHIC ROCK: GARNET SCHIST!1 - 2 billion years old!
36
What are three example rocks of Taos?
!Coral reefs in ancient seas deposits carbonates. !Carbonates react with acid, so an acid-test can
be used to help identify such minerals.!
MYSTERY - Why does the white coating on 4 million year old BASALT lava flows react to acid the same way that the 300 million year old SHALE does?