Minerals

Goals 1) To understand what minerals are and how they are put together; 2) To examine some important ore minerals; and 3) To examine some of the most common rock forming minerals

To earn the name mineral Naturally occurring and inorganic solid Characteristic chemical composition Regularly repeating internal crystalline structure Silicon + 2 oxygen SiO 2

Who has earned the name Ice (H 2 O) is a mineral, liquid water is not: Why? Quartz (SiO 2 ) is a mineral, glass is not: Why?

Atoms and atomic bonds Why are diamonds hard and pencil “leads” (graphite) soft? Graphite Diamond Diamond Saw

Atoms Nuclease of Protons (+) and Neutrons (0) Cloud of orbiting Electrons (-)

Electrons (e-) Electrons are divided into groups called orbitals Outer orbital of Hydrogen and Helium can hold 2 electrons Outer orbitals of all other atoms can hold 8 electrons Orbitals 2 e- 8 e-

Chemical bonds All atoms are greedy little buggers—They all want a full outer orbital, and they’ll bond with almost anyone to get it! Chemical bonds allow atoms to exchange or share electrons Methane: Carbon bonded to four hydrogen atoms

Ionic bonds One atom’s trash is another atom’s treasure Cations: throw away their outer electrons—net positive charge Anions: pickup cast-off electrons—net negative charge Salt combines sodium cation (Na + ) with chlorine anion (Cl - )

Covalent bonds Atomic monogamy: Atoms share outer electrons with a few partners. Strongest type of bond In methane carbon shares one outer e- with 4 hydrogen atoms quartz contains covalent bonds

Metallic bonds Atoms have a giant electron orgy Nuclei float in a sea of shared electrons

Intermolecular bonds Bonded atoms do a little sharing on the side Weakest type of bond! Some molecules have a weakly positive side and a weakly negative side Water

Think-pair-share activity 1.We know that diamonds are one of the hardest substances known to man and graphite is one of the softest. Both are made entirely of carbon 2.Come up with an explanation for this. 3.Compare, discuss, and refine your idea with one or two of your neighbors. 4.Write up your results and pass them in.

Diamond Graphite Different types of bonds

Crystalline structure Geometric arrangement of atoms Dictated by the types of elements present and the pressure and temperature conditions

Diamond Graphite Same chemical composition, different pressure and temp.

Important ore minerals Ore: metal-bearing mineral or rock that can be mined for a profit Jet engine—We need iron (steel), titanium, and aluminum... where do we get these metals?

Oxide minerals metal atoms covalently bonded to oxygen Hematite and magnetite — Iron oxides Our primary source of iron Found in banded iron formations (BIF’s) Most BIF’s 2–3 b.y. old

Rutile — Titanium oxide One of our main sources of titanium Often concentrated in beach sands

Bauxite — Aluminum bonded with oxygen and hydrogen (aluminum hydroxide) The main source of aluminum Forms due to extreme weathering in tropical soils

Iron (steel), titanium, and aluminum in this jet engine come from: 2.5 b.y. old rocks deposited in the deep ocean Beach sand Tropical soil No puppies were harmed in the making of this jet engine

Pyrite — Iron sulfide Common in coal beds and ore deposits Source of much acid mine drainage Sulfide minerals metal atoms ionically bonded to sulfur

Chalcopyrite — Copper-iron sulfide Often found in volcanic rocks found at convergent margins Primary source of copper

Rock forming minerals Minerals that make up most of the earth

Most common elements in the crust 1.Oxygen 2.Silicon 3.Aluminum 4.Iron 5.Calcium 6.Magnesium 7.Sodium 8.Potassium

Silicate minerals Silicate minerals—built around pyramid-shaped combinations of silicon and oxygen atoms called silica tetrahedrons Silica tetrahedron: Silicon atom covalently bonded to 4 oxygen atoms

Silicate minerals fall into two categories: Mafic minerals—silica tetrahedrons bonded to iron, magnesium, and calcium Felsic minerals—silica tetrahedrons bonded to aluminum, potassium, and sodium Generally dark colored More dense Common in oceanic lithosphere Generally light colored Less dense Common in continental lithosphere

Mafic minerals Olivine—single silica tetrahedrons covalently bonded to magnesium or iron Makes up 90% of the mantle

Mafic minerals Pyroxene—chain of silica tetrahedrons bonded to magnesium, iron, and calcium

Mafic minerals Amphibole—double chain of silica tetrahedrons bonded to magnesium, iron, and calcium

Mafic minerals Biotite—sheets of silica tetrahedrons bonded to magnesium, iron, and potassium

Felsic minerals Muscovite—sheets of silica tetrahedrons bonded to aluminum and potassium

Felsic minerals Potassium feldspar—network of silica tetrahedrons bonded to potassium and aluminum

Felsic minerals Quartz—network of silica tetrahedrons Silicon dioxide Most common mineral in crust

Plagioclase feldspar minerals Plagioclase feldspars—network of silica tetrahedrons bonded to calcium (mafic) and/or sodium (felsic) Calcium plagioclase feldspar = mafic Sodium plagioclase feldspar = felsic

Calcium plagioclase feldspar = black lab puppy Sodium plagioclase feldspar = yellow lab puppy Potassium feldspar = golden retriever puppy Sodium+Calcium plagioclase feldspar = chocolate lab puppy Mafic Felsic Feldspar minerals are like retriever puppies

Other important mineral groups Clay minerals—Sheet silicates that form due to chemical alteration at the Earth’s surface Very common in soils Used to make paper, ceramics, and bricks

Other important mineral groups Carbonate minerals—Combine carbonate ions (CO 3 2- ) with calcium to make Calcite and calcium and magnesium to make dolomite  Extremely important to global carbon dioxide cycles