Minerals

A mineral is a… ADD HERE

NATURAL

Minerals are created by the… ADD HERE

INORGANIC

Minerals are not made by living things or are composed of living

things.

CRYSTALLINE

The arrangement of atoms within a mineral creates a crystalline structure… ADD

HERE

CHEMICAL COMPOSITION

Minerals are composed of one element or many elements… ADD HERE

Chemical Composition of Minerals

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Ex: Sulfur = S

Some minerals are composed of a combination of

elements… ADD HERE

Ex: Fluorite = CaF2

(combination of calcium and fluorine)RT = Pg. 16

Crystalline Structure of Minerals

The atoms with a mineral are arranged and bonded in a specific way creating the crystalline structure of the

mineral.

The crystalline structure of a mineral helps to determine that mineral’s physical and chemical properties – such as

hardness and cleavage.

The majority of the Earth’s crust (by mass and volume) is made up of the elements oxygen and

silicon. The “silicon-oxygen tetrahedron” is the basic

building block of many minerals.The arrangement of silicon-oxygen

tetrahedrons… ADD HERE

Rock vs. MineralA rock is a… ADD HERE

All minerals are rocks, but not all rocks are minerals.

Most rocks are composed of one or more minerals. Some rocks are composed of

glassy or organic materials

COAL

Coal is composed of the… ADD HERE

Minerals are…ADD HERE

OBSIDIAN

Obsidian is volcanic glass that is formed by heated rock being cooled very quickly. Glass has a

noncrystalline atomic structure.

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Mineral Properties and Identification The best method for

mineral identification is through the use of X-ray

diffraction.

A beam of X-rays passing through a

mineral sample will diffract leaving a unique

“x-ray pattern” on photographic film.

Each mineral has its own unique diffraction

pattern.

Minerals have a unique set of physical and chemical properties that reflect its internal arrangement of atoms.

When in the field, scientist will use other methods to identify minerals.

Mineral Properties and Identification Color

The color of a mineral can be used for identification in some cases. Many times minerals will change due to impurities found within the rock

or mineral.

Color is NOT a reliable mineral property used in identification

SULFURSulfur is well known for

its yellow color.

QUARTZAll three samples are of

the same mineral. In this case color would not be useful tool in mineral

identification.

Mineral Properties and Identification Streak

The residue of a mineral… ADD HERE

The streak color does not always match the color of the mineral.

The streak of a mineral is more consistent than the

color of a mineral and, therefore, is a more

reliable test for mineral identification.

HEMATITEHematite is a silver colored mineral.

When scratched on a porcelain plate, its streak is reddish-brown.

Mineral Properties and Identification Luster

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Minerals may have… ADD HERE

A mineral with a metallic luster shines like a metallic surface (Ex: clean steel pot).

Most minerals have a nonmetallic luster.

PYRITEPyrite has a metallic luster and

shines like a metallic surface in the light.

OLIVINEOlivine does not shine like a metallic

surface in the light. It has a nonmetallic luster.

Mineral Properties and Identification Hardness

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Moh’s Hardness Scale is a tool used by scientists to determine the hardness of a mineral. Scientists can determine whether an unknown mineral can “scratch” or be “scratched” by known common materials.

This will help a scientist determine the hardness of an unknown mineral.

Gypsum has a hardness of 2 and calcite has a harness of 3. A

fingernail has a hardness of 2.5. A fingernail can “scratch”

gypsum and “be scratched” by calcite.

Mineral Properties and Identification Cleavage

The tendency of a mineral… ADD HERE

Zones of weakness found within a mineral relate to the crystalline structure of

the mineral.

Sometimes zones of weakness can be seen as

smooth sides with a luster.

Minerals that lack zones of weakness… ADD HERE

MUSCOVITE MICA

GALENA

CLEAVAGE:Zones of weakness

FRACTURE:Uneven brake

Mineral Properties and Identification

Other Tools for Mineral Identification

Specific Gravity

Specific gravity is the density of a

mineral compared to that of water.

Crystal ShapeADD

HERE…

Reaction with HCl acid

Certain minerals will… ADD HERE