Minerals and rocks

Rocks, they rock

Bohr Model Atom

Bohr Model Atom

an Atom that consists of positive protons and neutral Neutrons in the nucleus, with negative electrons orbiting.

Cation

An atom that has lost electrons, making it positive (think Pawsitive)- left side of periodic table

Anion

an atom that has gained electrons, making it negative- right side of periodic table

Ionic bond

One atom gives electrons to another, causing electrostatic attraction

Covalent Bond

Two atoms share electrons, this is the strongest bond as the nuclei are close together

Metallic bond

Only forms in metals, the electron clouds of the various atoms merge together. this is very weak bond.

Top 8 most abundant elements in crust

O, Al, Si are 98%, then Fe, Ca, K, Mg, Na

Mineral Definition

Naturally occurring, inorganic(No CHO), crystalline solid (lattice)

Crystal Lattice

regular 3D repeated arrangement of Atoms

what is natural glass

Natural glass is a supercooled liquid

What are the 8 physical properties used to identify minerals

Color, Hardness, Density, Luster, Magnetism, reaction to acid, cleavage, and Diaphaneity(transperancy

Color

Most minerals have one color, but some have many, so don’t rely on color.

Hardness/Moh’s Hardness Scale

Scale for measuring the hardness of a mineral

2.5 is fingernail

6.5 is Steel nail

Cleavage

The tendency to break in perfect parallel planes, sometimes in multiple directions, determined by crystal structure

Fracture-

Irregular breaking surface, can be flat but never parallel

Conchoidal Fracture

Fractures that occur in glass like obsidian, contains whorls and circles

Density

Some minerals are noticeably heavier than expected

Reaction to HCl

some minerals, mostly just calcite, fizz in reaction to HCl

Magnetism

A few minerals, notably magnetite, are magnetic

Luster

Minerals are either metallic, glassy or earthy

Diaphaneity

Minerals are either transparent or non-transparent

The 7 mineral types

Natural elements, Halites, Carbonates, Oxides and hydroxides, sulfides, sulfates, and Silicates

Natural elements

Pure forms of elements

Carbonates

Cation + CO3

Halides

Cation+a halogen

Oxides and Hydroxide

Cation + O or OH

Sulfides

Cation + S

Sulfates

Cation + SO4

Silicates

Cation + SiO with different amounts of oxygen depending on the shape. This is the most important group

Silicate Tetrahedron

Cation + SiO4. Base building block of silicate minerals, all Silicates are made of these linked in different ways.

Single Silicate Tetrahedra

cation + SiO4. 4: 1 silicon to oxygen ration. Ex: Olivine Mg2SiO4

Single Chain Silicate

Tetrahedra share a corner oxygen. 3:1 ration. 90 degree cleavage. Ex: Pyroxene MgSiO3

Double chain Silicate

Two single chains linked by a corner oxygen. 2.75:1 ratio. 60-120 degree cleavage. Ex: Amphibole

Sheet silicate

Tetrahedra share 3 oxygens. Forms sheet for cleavage. Ex: Muscovite

Framework Silicates

Tetrahedra share all oxygens. Ex: Quartz

Quartz

Any color, no cleavage, Harder than steel, glassy luster

Gypsum

Scratched by Fingernail, green to white, pearly luster, one direction of excellent cleavage

Plagioclase Feldspar

no scratches, 2 cleavages, white-gray with striations

K-Feldspar

No scratches, salmon pink, two cleavages

Amphibole

no scratches, 2 60-120 degree cleavages, jet black

Pyroxene

no scratches, 2 rough cleavages, black-green color

Olivine

No scratches, olive green, conchoidal fractures

Garnet

No scratch, No cleavage, glassy luster

Muscovite

scratched by steel, forms sheets, very transparent and slightly brown

Biotite

scratched by steel, forms sheets, dark brown

Halite

scratched by steel, cubic cleavage, salty

Calcite

Scratched by Steel, 3 cleavages at non-90 degree angles, reacts with HCl

Rock cycle

Rocks change from one type to another, through heat, pressure, weather, deposition, and other processes.

Crystal Face vs Cleavage Plane

Crystal faces are what face out as the mineral is formed while cleavage planes are a result of breakage.;