Minerals

Minerals

Naturally occurring Inorganic Crystalline solid (atoms are arranged in a

repeating pattern) Definite chemical composition

Why do we study Minerals? Starting point for all geologic formations and

activity Rocks and molten rock (lava, magma) are what

shape the surface of our planet

Minerals Can Be Elements or Compounds

Single elements that are also minerals are called native elements (ex: copper)

Most minerals are compounds made from different elements

8 most common elements: Oxygen, Silicon, Aluminum, Iron, Calcium, Sodium,

Potassium, Magnesium

How Minerals Form

1. The cooling and hardening of magma

2. When water containing dissolved ions evaporate

3. Sustained pressure, heat, or chemical action can change minerals into other minerals

Mineral’s Crystalline Structure All minerals are crystalline (all of their atoms are

arranged in a repeating pattern)

The atoms pattern can be used to identify a mineral

Crystal system controls the way a mineral forms and breaks

Crystal System Models

1. Color the shapes according the colors listed below. A:Red B: Blue C: Green D:Yellow E: Orange F: White

2. Cut them out

3. Fold them along all the black lines

4. Put glue on the small tabs and CAREFULLY glue them into the shapes they fold into.

5. You will need the small images of the crystals. Cut them and secure them in a safe place. Do NOT lose them!

The 6 Crystal Systems: #1 Cubic System 3 axes of equal length

that intersect at 90 degree angles

Example- Halite (Rock Salt)

The Six Crystal Systems #2 Orthorhombic System Three axis of different

length that intersect at 90 degree angles

Examples: Sulfur, Topaz

The Six Crystal Systems #3 Tetragonal System Three axes, 2 of the

same length, one that differs

Examples: Wulfenite

The Six Crystal Systems #4 Triclinic System Three axes of

unequal length that intersect at oblique angles.

Example: Turquoise

The Six Crystal Systems #5 Hexagonal System Three horizontal axes that

are the same length, and a vertical axis that is longer then the horizontal axes.

Example: Quartz Graphite

The Six Crystal Systems #6 Monoclinic System Three unequal axes,

two intersect at 90 degrees, the third is oblique to the other two

Example: Gypsum, Borax

Physical Properties Color: The color as it appears to the naked eye

Not effective in identifying minerals Some are similar in color Others can have their color changed Some come in multiple colors

Physical Properties Streak: the color of the powder a mineral leaves

after rubbing it on a streak plate.

More effective than color because the streak is often different than the color, and can be distinct to the mineral

Properties Cont’d Luster: the way a mineral shines and reflects light

Metallic Luster: Shines like a polished metal Ex: Pyrite, Galena, Hematite, Magnetite

Non-Metallic: Anything non-metallic. Ex: Quartz, Fluorite, Sulfur, Opal

Mohs Hardness Scale Hardness: A mineral’s resistance to being

scratched

Moh’s Hardness Scale: The hardness of minerals relative to each other/scratching implements.

These are labeled 1-10, 1 being the softest, 10 the hardest.

Mineral Tools

1.Talc Fingernail

(2.5)2.Gypsum

3.Calcite Nail

(Avoid the point)

(4.5)

4.Fluorite

5.Apatite Glass

(5.5)6.Feldspar

7.Quartz Streak Plate (5-8)8.Topaz

9.Corundum

10. Diamond

Cleavage Cleavage: the tendency of

a mineral to split along a certain plane or planes

Not all minerals have cleavage

We describe it in numbers of planes and angles of intersection

Fracture Fracture: When minerals don’t

break along certain planes

3 KINDS Conchoidal: Shell Like and

smooth Hackly: Jagged Edges Fibrous: Breaks into strands

Special Properties Texture: Having a unique feel to the touch (talc,

graphite)

Effervescence: Reacts by bubbling when exposed to hydrochloric acid (calcite, dolomite)

Taste: What does it taste like?… Duh… (Halite/Rock Salt)

Special Properties Cont’d Smell: (Sulfur smells like eggs)

Magnetism: Mineral has magnetic properties (Magnetite)

Density: the amount of water it displaces (Metallic lusters are generally denser)

Phosphorescence: Does it glow under black light? (Fluorite)

Today = Finish Dummies Guide

Make sure all information is complete.

All charts and test are complete.

Accurately identify minerals A, B, C, D using your notes and classification chart.

The Silicates

Silicates: Compound of the elements Silicon and Oxygen

90% of minerals are silicates

Form from the cooling of Lava/Magma

The Si and O join to form Silicon-Oxygen Tetrahedrons

Silicate Minerals:

Quartz: Multiple forms of quartz

(rose, amethyst, crystal) Conchoidal Fracture Mohs Hardness: 7 Luster: Glassy

Silicate Minerals Continued…

Feldspar: The most abundant family

of minerals in earth crust Plagioclase or Orthoclase

Feldspar 2-3 directions of cleavage Mohs Hardness: 6 Luster: Pearly

Silicate Minerals Continued…

Mica 2 Types Muscovite mica (white

mica), and Biotite mica (black or brown)

One distinct Cleavage (makes long sheets)

Mohs Hardness: 2.5 Luster: Pearly

Silicate Minerals Continued…

Talc The softest mineral,

talcum powder is pure ground up talc

1 direction of cleavage Mohs Hardness: 1 Luster: Pearly/Oily

Silicate Minerals Continued…Olivine: Olive green silicate Belongs to a family where

silicates bond to metal ions, ocassionally found in meteors

Conchoidal Fracture Mohs Hardness: 6.5 Luster: Glassy

Silicate Minerals Continued…

Garnet: A very common

gemstone Conchoidal Fracture Hardness: 6-7.5 Luster: Vitreous to

resinous

Other Mineral Groups

Carbonates 2nd most common mineral group Contains the elements carbon and oxygen

and one or more other metallic elements EX. Calcite, Dolomite

Carbonate Minerals

Calcite: Composed of Calcium

Carbonate (CaCO3)

CALCITE FIZZES WITH ACID!!!

3 directions of cleavage Mohs Hardness: 3 Luster: Glassy

Carbonate Minerals

Dolomite: Composed of a Magnesium

Carbonate (MgCO3) 3 directions of cleavage Mohs Hardness: 3.5 to 4.0 Luster: Glassy/Vitreous

Halides: Contain a halogen ion plus

one of more elements

Formed from salt water evaporation

EX. Halite, Fluorite

Other Mineral Groups

Other Mineral Groups

Sulfides/ Sulfates:

Contain the element sulfur and one other element, often metallic

EX. Gypsum, Pyrite

Bellringer Quiz

1. ______The way a mineral reflects or “reacts” to light 2. ______A mineral’s resistance to being scratched 3. ______ Includes taste, effervesence, smell, phosphorescence 4. ______Describes the way minerals naturally split 5. ______The color of a minerals powder when rubbed across an

unglazed porcelain plate 6. ______When minerals don’t break along cleavage lines 7. ______Considered to be a not-reliable way to I.D. minerals 8. Define mineral! 9. Why are color AND luster unreliable for IDing minerals?

Other Mineral Groups Oxides: Contain oxygen and one

or more other element usual a metal.

Can form from magma or from weathering

EX. Hematite (Rust), Corundum, Magnetite

Other Mineral Groups

Native Elements:elements that exists in relative pure forms

Many form from hydrothermal solutions

EX. Diamond and Graphite (carbon), silver, gold, copper, sulfur

Mineral uses Talc – talcum powder Quartz – Glass, Sand Paper, Amethyst Gems Diamond – Gems, drills Beryl – Emerald Gems Corundum – Ruby Gems Gypsum – Drywall Halite – Rock Salt Copper – Wire, Jewelry, etc… Galena - Lead ore

Bellringer Picture

Iron Oxide and Sulfates

Oxides

-A mineral consisting of a metal element combined with oxygen

Sulfates

-A mineral consisting of a metal element combined with sulfur

Iron Oxide Minerals

Hematite The most common Iron

Oxide mineral Red to brown streak on

streak plate Mohs Hardness: 5 to 6 Luster:Metallic (sometimes

earthy if it gets worn down)

Iron Oxide Minerals

Magnetite: A black magnetic iron oxide Mineral has magnetic

properties Black streak Mohs Hardness: 5.5 to 6.5 Luster: Metallic to Dull

Iron SulfidesPyrite: An Iron Sulfide (Fe3SO4) Occurs in 6 and 12 sided

crystals “Fools Gold” Greenish-Black streak Mohs Hardness: 6.0 Luster: Metallic