1. Atoms, Compounds, Minerals and Rocks

2. Atoms Atoms - the smallest unit of an element that retains the physical and chemical properties of that element Made up of a nucleus, and a “cloud” of electrons Nucleus made up of protons and neutrons Number of protons determines which type of Element the atom is Element - distinctive type of matter with specific phyisical and chemical properties Examples: Iron, Oxygen, Hydrogen, etc. Generally grouped as Metals or Nonmetals

3. Compounds Compound - substances made by the bonding of chemical elements (from chemical reactions). Compounds are comprised of two or more different elements. Chemical bonds may be made by – – sharing electrons between atoms - covalent bonds – – lending or borrowing electrons with mutual attraction of oppositely charged atoms - ionic bonds The properties of compounds are dramatically different from those of the elements that comprise them

4. A Mineral is Naturally occurring Naturally occurring Inorganic (not made from animals or plants) Inorganic (not made from animals or plants) Solid Solid with a definite chemical composition (formula) with a definite chemical composition (formula) and an orderly arrangement of atoms (crystal structure) and an orderly arrangement of atoms (crystal structure) Minerals are chemical compounds

6. Crystal Structure How do crystals form? How do crystals form? Atoms must be free to move Atoms must be free to move Chemical bonds dictate the geometric arrangement of atoms Chemical bonds dictate the geometric arrangement of atoms Crystal is external manifestation of order at atomic level Crystal is external manifestation of order at atomic level

7. Crystal Structure Atoms must be free to move Atoms must be free to move Under what conditions does this occur? Under what conditions does this occur? In a melt (magma) In a melt (magma) In solution (dissolved in water) In solution (dissolved in water)

8. Abundance of chemical elements in Earth’s Crust O – 46.6%Si – 27.7% O – 46.6%Si – 27.7% Al – 8.1%Fe – 5.0% Al – 8.1%Fe – 5.0% Ca – 3.6%Na – 2.8% Ca – 3.6%Na – 2.8% K – 2.6%Mg – 2.1% K – 2.6%Mg – 2.1% Other – 1.7% Other – 1.7%

9. Silicate Minerals O and Si make up nearly 75% of crust O and Si make up nearly 75% of crust Most common elements should make up most common minerals Most common elements should make up most common minerals Common “rock-forming” minerals are silicates Common “rock-forming” minerals are silicates Silicates have Si, O and other elements such as Fe, Mg, Al, Na, K, Ca Silicates have Si, O and other elements such as Fe, Mg, Al, Na, K, Ca

10. Silicon-Oxygen Tetrahedron “Building Block” of Silicate minerals “Building Block” of Silicate minerals Si surrounded by 4 O Si surrounded by 4 O O may be shared so that tetrahedra link together O may be shared so that tetrahedra link together

11. Sharing Tetrahedra

12. Olivine – Fe,Mg silicate Single Tetrahedra

13. Pyroxene – Fe, Mg, Al silicate Single Chains

14. Amphibole – Fe, Mg, Ca, Na, Al, F silicate

15. Micas (biotite, muscovite) – K, Al +/-Ca, Mg, Fe silicates

16. Complex silicates Quartz SiO 2 Quartz SiO 2 Feldspars Feldspars –Na,Ca silicates Plagioclase –K, Al silicates Other minerals Other minerals

17. Bowen’s Reaction Series

18. Other Mineral “Families” Halides – contain metals and Cl, F, I, etc. Halides – contain metals and Cl, F, I, etc. Carbonates – contain metals and CO 3 Carbonates – contain metals and CO 3 Oxides/Hydroxides – contain metals and O or OH Oxides/Hydroxides – contain metals and O or OH Sulfides – contain metals and S Sulfides – contain metals and S Phosphates – contain metals and PO 4 Phosphates – contain metals and PO 4 “Native” Elements – pure elements “Native” Elements – pure elements

19. So, What is a Rock? A Rock is: An “aggregate” of minerals Usually, a mixture of two or more minerals, each of which remains distinct