minerals, rocks, and rock forming processes · minerals • because of their abundance, oxygen and...

Energy and Matter

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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

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Rocks

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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! !

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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!

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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?