minerals
DESCRIPTION
Minerals. Composition of the Sun. Composition of the Sun. Abundance of Light Elements Rarity of Lithium, Beryllium, Boron Preference for Even Numbers Abundance peak at Iron, trailing off after. How Elements Form in Stars. Sun: 4 H He He + particle Mass 5 – Unstable - PowerPoint PPT PresentationTRANSCRIPT
Minerals
Composition of the Sun
Composition of the Sun• Abundance of Light
Elements
• Rarity of Lithium, Beryllium, Boron
• Preference for Even Numbers
• Abundance peak at Iron, trailing off after
How Elements Form in Stars
• Sun: 4 H He
• He + particle Mass 5 – Unstable
• He + He Mass 8 – Unstable
• He + He + He C
• Add more He to make heavier elements
• End of the line is iron for energy production
• Atoms beyond Iron made in massive stars
What are Planets Made of?
• Same material as Sun
• Minus the elements that remain mostly in gases
• We find this pattern in a certain class of meteorites
Chondrites
The Earth’s Crust looks Very Different
Composition of the Crust
Minerals are the Chemicals that make up the Earth
• NATURALLY-OCCURRING
• INORGANIC
• CHEMICAL COMPOUNDS
• ABOUT 3000 KNOWN
• 200 COMMON
• 20 ROCK-FORMING
Atomic Bonding 1. IONS
Atomic Bonding2. ELECTRICAL NEUTRALITY• (+) and (-) Cancel Out
3. BONDING (SATISFY 1 & 2)• Ionic (NaCl) • Covalent (O2) • Metallic (Cu, Al, Fe) • Hydrogen (in water)
Ionic and Covalent Bonding
Metallic Bonding
Hydrogen Bonding
Summary of Bonding
• Ionic bonding holds rocks and minerals together
• Covalent bonding holds people and other organisms together
• Metallic bonding holds civilization together
• Hydrogen bonding gives water its heat-retaining and solvent properties
4. Lattices• Atoms in crystals form a repeating pattern
called a Lattice
5. Radicals• Many minerals contain groups of atoms that
behave as single units
NAMING MINERALS COLOR• Glauconite (Greek: Glaucos = Blue-green) OTHER PROPERTIES, USES• Magnetite COMPONENTS• Chromite PLACES• Muscovite (Moscow) PEOPLE• Biotite
CHEMICALS (AND MINERALS) ARE
CLASSIFIED BY THEIR ANIONS
For Example: Iron Compounds Have Little in Common
• Fe: Gray, Metallic
• FeCl2: Light Green, Water Soluble
• FeSO4: Light Green, Water Soluble
• FeCO3: Brown, Fizzes in Acid
• FeS2: Dense, Brittle, Metallic, Cubic Crystals
On the Other Hand, Sulfides have Many Properties in Common
• FeS2
• CuFeS2
• PbS
• ZnS2
All are Dense, Brittle, Metallic, have Cubic Crystals
IDENTIFYING MINERALS
COLOR -Sometimes Distinctive
• Often Unreliable
• Affected By:– Chemical Impurities – Surface Coating – Grain Size – Weathering
IDENTIFYING MINERALS (Continued)
HARDNESS • Resistance to Scratching • Directly related to relative strength of
atomic bonds • Scratch Test (Mohs) • Indentation Test (Knoop) Common Errors due to:• Weathering, ‘Chalk' marks • Breaking vs. Scratching
Mohs vs. Knoop Scales 1. Talc: very small 2. Gypsum, Fingernail: 30 3. Calcite, Penny: 135 4. Fluorite: 163 5. Apatite: 430 6. Feldspar, Glass: 560 7. Quartz: 820 8. Topaz: 1340 9. Corundum: 2100 10. Diamond: 7000
IDENTIFYING MINERALS (Continued)
DENSITY
• Directly related to masses of component atoms and their spacing
• Usually very consistent
DENSITY - gm/cm3
(weight relative to water )• Air: 0.001
Wood - Balsa: 0.1, Pine: 0.5, Oak: 0.6-0.9Gasoline: 0.7, Motor Oil: 0.9Ice: 0.92Water: 1.00Sugar: 1.59Halite: 2.18Quartz: 2.65Most Major Minerals: 2.6-3.0Aluminum: 2.7
DENSITY• Pyrite, Hematite, Magnetite: 5.0
Galena: 7.5Iron: 7.9Copper: 9Lead: 11.4Mercury: 13.6Uranium: 19Gold: 19.3Platinum: 21.4Iridium: 22.4 (densest material on Earth)
IDENTIFYING MINERALS (Continued)
LUSTER
• Metallic or Nonmetallic is the most important distinction.
• Resinous, waxy, silky, etc. are self-explanatory.
• Vitreous is often used for glassy luster.
IDENTIFYING MINERALS (Continued)
CLEAVAGE • Tendency to split along smooth planes
between atoms in crystal • Thus directly related to atomic structure • Related to Crystal Form • Every cleavage face is a possible crystal face • Not every crystal face is a cleavage face.
Quartz commonly forms crystals but lacks cleavage.
IDENTIFYING MINERALS (Continued)
CRYSTAL FORM
• Takes Luck & Practice
• Well-formed crystals are uncommon
• Crystal Classification is somewhat subtle
FRACTURE
IDENTIFYING MINERALS (Continued)
GEOLOGIC SETTING • Some minerals occur in all geologic settings:
quartz, feldspar, pyrite • Some minerals occur mostly in sedimentary
settings: calcite, dolomite • Some minerals occur mostly in igneous
settings: olivine • Some minerals occur mostly in metamorphic
settings: garnet, kyanite
IDENTIFYING MINERALS (Continued)
SPECIAL PROPERTIES
• Taste, Magnetism, Etc.
EXPERIENCE AND READING
PROFESSIONAL METHODS
• Chemical Analysis
• X-Ray Studies
• Thin Section
Diffraction
Diffraction
MAJOR MINERAL SUITES
ELEMENTS
Metallic:Au, Ag, Cu
• Not Al, Pb, Zn, Fe, etc.
Nonmetallic: C - Diamond, Graphite
• Sulfur
MAJOR MINERAL SUITES
SULFIDES: Dense, Usually MetallicMany Major Ores
• Pyrite FeS2
• Chalcopyrite CuFeS2
• Galena PbS
• Sphalerite ZnS2
• Molybdenite MoS2
MAJOR MINERAL SUITES
HALIDES: Usually Soft, Often Soluble
• Halite NaCl
• Fluorite CaF2
SULFATES: Soft, Light Color
• Gypsum CaSO4
• Barite BaSO4
MAJOR MINERAL SUITES
OXIDES: Often Variable, Some Ores
• Hematite Fe2O3
• Bauxite Al(OH) 3 (a hydroxide)
• Corundum Al2O3 (Ruby, Sapphire)
CARBONATES: Fizz in Acid, Give off CO2
• Calcite CaCO3
• Dolomite CaMg (CO3)2
MOST IMPORTANT MINERAL SUITE:
The Silicate Minerals
• Si + O = 75% of Crust
• Silicates make up 95% + of all Rocks
• SiO4: -4 charge
• Link Corner-To-Corner by Sharing Oxygen atoms
Nesosilicates - Isolated Tetrahedra
Representatives:•Garnet •Kyanite •Olivine
Sorosilicates - Paired Tetrahedra
Epidote is the most common example
Cyclosilicates - Rings
•Beryl (Emerald) •Tourmaline
Inosilicates - Chains Single Chains (Pyroxenes)
Inosilicates - Chains Double Chains (Amphiboles)
Phyllosilicates - Sheets
Phyllosilicates - Sheets
Si2O5 sheets with layers of Mg(OH)2 or Al(OH)3
• Micas
• Clay minerals
• Talc
• Serpentine (asbestos) minerals
Tectosilicates - Three-Dimensional Networks
• Quartz Feldspars
Unit Cells All repeating patterns can be described in terms
of repeating boxes
The problem in Crystallography is to reason from the outward shape to the unit cell
Which Shape Makes Each Stack?
Stacking Cubes
Some shapes that result from stacking cubes
Symmetry – the rules behind the shapes
Symmetry – the rules behind the shapes
The Crystal Classes