Unit 3 – Minerals and Rocks Do Now – Number the pages (there should be 40) HW – You may clean out your folders

Minerals are: What is a Mineral? Today’s Objective: What is a Mineral? Important Vocabulary Minerals are: Naturally occurring – Forms by natural geologic processes. Solid substance

Definite chemical composition – most are made up of two or more elements. Inorganic – not living Calcite primarily comes from the remains of shells from living organisms

Orderly crystalline structure – atoms are arranged in an orderly and repetitive manner. Crystals – A solid body having a visually symmetrical pattern to it’s atomic arrangement

Sand (SiO4) is a common silicate Example - Crystalline Structures Silicon and Oxygen combine to form a structure called the Silicon-Oxygen Tetrahedron. Sand (SiO4) is a common silicate

Because the atoms are arranged differently. The following minerals are both made of pure Carbon, why do they look different? Graphite Diamond Because the atoms are arranged differently.

As the water evaporates the sugar is left behind How are minerals formed? Precipitates Minerals are left behind from a body of water when it evaporates Example - Rock Candy As the water evaporates the sugar is left behind

Changes minerals into new minerals Heat and Pressure Changes minerals into new minerals Crystallize Minerals that form out of cooling magma

Hydrothermal Super heated water causes chemical reactions that change minerals into new ones.

its internal arrangement of atoms. A mineral’s properties are caused by its internal arrangement of atoms.

Properties of Minerals Color (NOT reliable) Many minerals have the same color OR one mineral can have many colors Small amounts of different elements can give the same mineral different colors.

Streak - Streak is the color of a mineral in its powdered form. - Streak is obtained by rubbing a mineral across a streak plate (a piece of porcelain.)

Hardness Hardness is a measure of the resistance of a mineral to being scratched on glass. The Mohs scale consists of 10 minerals arranged from 10 (hardest) to 1 (softest). Glass has a hardness of about 5.5

Other - Few minerals bubble in the presence of an acid (Calcite and Dolomite)

Cleavage - Cleavage is the tendency of a mineral to cleave, or break, along flat, even surfaces. Fracture - Fracture is the uneven breakage of a mineral.

Luster - Luster is used to describe how light is reflected from the surface of a mineral. Metallic vs. Non-Metallic

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