TOPIC 11 ROCKS MINERALS Minerals are the ingredients

TOPIC 11 ROCKS & MINERALS

• Minerals are the ingredients of rocks. Or • Rocks are made up of minerals.

Minerals • Defn: naturally occurring, inorganic elements or compounds with specific physical and chemical properties.

Mineral Properties v Used to identify minerals 1. Color • Least useful property in identifying minerals. • Why?

All of these are varieties of quartz!

2. Streak • • The color of a minerals powder. “streak test”

3. Luster • How the minerals surface reflects light. • Metallic vs. non- metallic.

4. Hardness • • • The ability of a mineral to resist being scratched. “Scratch test” If mineral A can scratch mineral B, what does that tell us about the relative hardness of each mineral?

Moh’s Hardness Scale Soft Hard

5. Fracture/ Cleavage Fracture • Mineral breaks unevenly or irregularly Cleavage • The tendency of a Mineral to break evenly along its weakest plane.

6. Crystal Form • Some minerals tend to form crystals that aid in the identification of the mineral.

7. Specific Gravity • The ratio of the density of the mineral to the density of water (1 g/cm 3) • If a mineral has a specific gravity of 5 that means it is 5 times as dense as water.

8. Others • • • Acid test – Calcite Magnetic – Magnetite Taste - Halite

v. A minerals properties are due to the internal arrangement of its atoms.

Silicate Minerals • Minerals that contain a combination of silicon and oxygen. Silicon-oxygen tetrahedron The basic structural unit of silicate minerals

Rocks Monomineralic • 1 Mineral Polymineralic • More than 1 Mineral v Rocks are classified by how they are formed!!!

Sedimentary Rocks: 1. Clastics • Rocks that form when sediments (sand, silt etc. ) are lithified. Processes • Compacting and cementing • Vary due to grain size! (see ref tables p. 7)

2. Non-Clastics A. Organics (bioclastics) • Form from living things. Examples: Coal, limestone B. Chemical (crystaline) • Formed from the evaporation or precipitation of sea water. Examples: Halite, gypsum

Igneous: - Form when liquid rock cools and solidifies Intrusive • Cools below the earths surface (slowwwwly!) • Magma • “Plutonic” Extrusive • Cools at the Earths surface (quickly!) • Lava • “Volcanic”

v. The longer the rock takes to cool, the larger the crystals! • Cools slow …. . Large crystals • Cools fast ……. small crystals • Cools immediately……NO Crystals (glass)

Vesicular- gas pockets

Metamorphic: • • Rocks that are changed due to extreme heat and/or pressure. DO NOT MELT!!! (they recrystalize) Metamorphic rocks become… 1. 2. 3. 4. Harder More dense Banded or foliated Distorted

Banding

Foliated

Regional Metamorphism • Occurs when large areas of rock are changed. • Usually deep below the surface where crustal plates collide. • The Adirondacks!

Contact Metamorphism • Occurs when liquid rock comes into contact with other rocks.

Bedrock Of New York State

Identifying Characteristics of Rocks Igneous • Intergrown crystals • Glassy texture Metamorphic • Banding • Foliated Sedimentary • Cemented fragments (sediments) • Fossils • Organic material

The Rock Cycle

BONUS: • CLASSIFY this rock as igneous, sedimentary or metamorphic and EXPLAIN why you classified it that way.

BONUS: Name the mineral that has the following properties: • Non-metallic • Can scratch fluorite but cannot scratch quartz • Exhibits cleavage • Contains the elements sodium & hydrogen