1. Minerals & Rocks
Honors Notes

2. A Mineral is a naturally occurring Inorganic Solid with a definite chemical composition and a crystalline structure.

3. Lets put that in a list format:
1. Minerals are a naturally occurring substance.
2. Minerals are solids.
3. Minerals have a definite chemical composition.
4. The atoms that make up minerals are arranged in an orderly pattern (They form crystals).
5. Minerals are inorganic. (They were never alive.)

4. Two Major Types of Minerals
Silicate Minerals
Contain silicon (Si) plus oxygen (O) or silicon dioxide (SiO2).
The most common rock-forming minerals
May contain one or more other elements with the silicon and oxygen.
EX: Feldspars are formed depending on what else combines with the silicon and oxygen.
Orthoclase- Si, O, K, AL
Plagioclase- Si, O, Ca, Na
EX: Quartz composed of only Si and O
Make up 96% of the Earth’s crust.
Earth’s oceanic crust is denser and contains a larger percentage of silicates than continental crust.

5. Silicate Minerals
Biotite
Quartz
Muscovite
Plagioclase
Feldspar

6. Two Major Types of Minerals (cont’d)
Non-silicates
Contain no silicon
Many important mineral groups are not silicates.
Non-Silicate Minerals include: carbonates, (limestone, marble) oxides (hematite), halides (halite/rock salt), sulfides (pyrite), sulfates (gypsum), and native metals (gold, silver, copper).
The non-silicate groups are a source of many valuable ore minerals and building materials.
To be an ore, a mineral must occur in large enough quantities to be economically recoverable.

7. Non-Silicate Minerals
Pyrite
Hematite
Halite (salt)

8. Non-Silicate Minerals
Gold
Flourite
Galena

9. Physical Properties Mineral appearance Hardness Luster
Specific gravity
Streak
Cleavage and fracture
Physical Properties

10. Mineral appearance How it looks like What color is it?
Which one of the following is gold? Identify by appearance.

11. Hardness A measure of how easily a mineral can be scratched
Mohs Hardness Scale
developed in 1812 by Friedrick Mohs (an Austrian mineral expert) as a method to identify minerals.

12. Luster The way a mineral reflects a light.
Either metallic or nonmetallic

13. Specific Gravity
The specific gravity of a mineral is the ratio of its weight compared with the weight of an equal volume of water.
Gold has specific gravity of 19
It means gold is 19 times heavier than water.
19 times heavier

14. Specific gravity

15. Streak
When a mineral is rubbed across a piece of porcelain tile a streak of powdered mineral is left behind.

16. Cleavage Cleavage is the way that mineral breaks.
Minerals that break along smooth, flat surfaces have cleavage.
Mica has cleavage
Cleavage

17. and Fracture!...
Mineral that breaks uneven, rough, or jagged surfaces have fracture.
Quartz has fracture
quartz

18. Atom Arrangement
Some physical properties are controlled by the orderly arrangement of atoms in a mineral’s structure.
The arrangement of atoms and the bonds between them can reflect the way a mineral breaks, how hard it is, and what types of crystal shape it has.

19. Crystal Shape – Types of Symmetry
Which of these would halite be the shape of?

20. Name
Plane
=Basal 1
=Prismatic 2 3
=Cubic
=Rhombo-
hedral 3

21. An illustration appearance:luster,color and streak

22. An illustration cleavage and fracture

23. Identify the minerals below for cleavage and fracture

24. Special Properties of Minerals
Magnetic – use a magnet and see if it sticks
Taste – certain minerals have a specific taste
Fluorescence – glowing while under a U.V. light
Phosphorescent – continues to glow after the U.V. light is off
Radioactive – test minerals with a Geiger counter
Double Refraction – Splits light rays into 2 parts. (see a double image) Look through the mineral for the image.

25. Rocks
A rock is a naturally formed consolidated solid mixture made up of minerals, rock fragments, or volcanic glass
Essential Minerals: always occur in the rock
Accessory Minerals: sometimes occur in rock

26. Classify Rocks by how they form
Igneous
- Made up of magma or lava when it cools and hardens
Sedimentary
- Made from sediments
Metamorphic
- Rocks changed by pressure & heat

27. Igneous Rocks Formed from lava or magma Intrusive Igneous rocks
Lava : extrusive or volcanic
Magma: Intrusive or plutonic (pillow-like)
Intrusive Igneous rocks
Formed from magma which cools and solidifies below Earth’s surface
Cooling and solidification take a long time resulting in large visible crystals (coarse-grained)
Extrusive Igneous Rocks
Small to no mineral crystals due to faster cooling lava above Earth’s surface (fine-grained)
Occurs at volcanoes or through ocean floor

29. Sedimentary Rocks
Rock is a fused mixture of minerals. Some of these minerals could be in bits and pieces of other rocks.
Broken into pieces (clasts) through weathering
Rock exposed at the surface is attacked by the weather
Water: enters cracks, expands, & breaks rocks down
Rain: acidic dissolves minerals
Movement in rivers: collects at the bottom

30. Sedimentary Rocks Formation
Build very slowly in layers, until the environment changes
Compaction: pieces compact due to weight squeezing them together
Cementation: minerals acting as cement holding sediments together
Precipitation: water evaporates & minerals are left behind

31. Classifying Sedimentary Rocks Clastic Rocks: pieces of other rocks

32. NonClastic Rocks
Minerals in water which evaporates to leave behind deposits (rocks) or fossil materials that compact into rock.
Ex:
1. Limestone: calcite and seashells
2. Rock salt: halite
3. Rock gypsum: gypsum
4. Chert: Quartz
5. Coal: fossil materials

33. Metamorphic Rocks
Form from pre-existing igneous, sedimentary, or metamorphic rocks, as a result of temperature and pressure changes
3 types of changes:
Rearrangement of mineral grains
Enlargement of crystals
Change in chemistry of rock

34. Characteristics of Metamorphic Rocks
Foliation: Foliated textures in metamorphic rocks have lots of layers or bands.
Non-Foliated: metamorphic textures include rocks whose grains are in more random orientations. (no bands)
Tend to have random crystal orientation and uniform grain size.
Mineral grains tend to grow larger as metamorphism increases.

35. Characteristics of Metamorphic Rocks
Foliation Nonfoliated

36. Hints for Identifying Rocks
Igneous
crystals intersecting at angles
size of the grain
Sedimentary
layers of rock pieces
Metamorphic
pressure created results in lines
pressure and heat create grains in foliation (wavy patterns)
hardest of the 3 rocks

38. Rock Cycle Changes of rocks from one rock type to another melting
Magma
melting
cooling
Metamorphic Rock
Igneous Rock
weathering
heat & pressure
Sediments
Sedimentary Rock
cementation or compaction