Follow-Up from Last Class

1. Follow-Up from Last Class Define the �population� from which your dust sample was taken Do you think it was a representative sample? Were your two samples similar? How might you sample more effectively?

2. Minerals

3. Minerals There are five characteristics that all minerals share: Minerals are NATURALLY OCCURRING Minerals are SOLID Minerals are INORGANIC� Minerals have specific CHEMICAL COMPOSITIONS Minerals have specific ATOMIC ARRANGEMENTS

4. Generalized Atomic Structure Nucleus houses the massive particles (protons and neutrons) # Protons = Atomic Number # Protons + Neutrons = Atomic Mass Responsible for mass and density Electrons lie in orbitals that surround the nucleus # Electrons = # Protons If not, then it is an ION Responsible for bonding

5. Ions Ions are electrically charged particles formed by the gain or loss of electrons Cations are positively charged Anions are negatively charged Metals are elements that readily form cations Non-Metals are elements that readily form anions

8. Mineral Classes Minerals involve bonds between cations and anions (metals and non-metals) Only a few elements form common anions(C, N, O, P, S, Cl) Minerals classified based on anions (non-metals)

9. Elemental Abundance in Crust

12. Most Minerals Are Silicates Crust is mostly Si & O Crust is made up mostly of minerals that include Si and O Silicates

13. Silica Tetrahedron The fundamental �architectural� unit of silicate minerals is the silica tetrahedron One Si ion bonded with four O ions

14. Silica Tetrahedron The silica tetrahedron is a complex ion An ion that contains a metal cation bound to one or more ions Overall charge on the silica ion is -4 Charge must be balanced to form a stable mineral

16. Isolated Tetraheda Silicates (Nesosilicates) Tetrahedra do not share any oxygens with neighboring silicon ions Charge balance achieved by bonding with cations e.g., Olivine, Garnet

17. Isolated Tetraheda Silicates (Nesosilicates) Is there a distinct shape to the crystal lattice? What shape will they take when they grow? Is there a difference in the bonds in different directions? What shape will they take when they break?

18. Isolated Tetrahedra Silicates

19. Ring Silicates (Cyclosilicates) Sets of tetrahedra share two oxygens to form a ring Remaining charge balance achieved by bonding with cations e.g., tourmaline, beryl

20. Ring Silicates (Cyclosilicates) Is there a distinct shape to the crystal lattice? What shape will they take when they grow? Is there a difference in the bonds in different directions? What shape will they take when they break?

21. Ring Silicates

22. Single-Chain Silicates (Inosilicates) Sets of tetrahedra share two oxygens to form a chain Remaining charge balance achieved by bonding with cations e.g., pyroxenes

23. Double-Chain Silicates (Inosilicates) Sets of tetrahedra share oxygens (2 and 3 alternation) to form a chain Remaining charge balance achieved by bonding with cations e.g., amphiboles

24. Chain Silicates: Habit

25. Chain Silicate Cleavage

26. Chain Silicates: Cleavage

27. Sheet Silicates (Phyllosilicates) Sets of tetrahedra share three oxygens to form a sheet Remaining charge balance achieved by bonding with cations e.g., micas, clays

28. Sheet Silicates (Phyllosilicates) Is there a distinct shape to the crystal lattice? What shape will they take when they grow? Is there a difference in the bonds in different directions? What shape will they take when they break?

29. Sheet Silicates Sheet silicates tend to break into sheets and flakes

30. Sheet Silicates

31. Framework Silicates (Tectosilicates) Sets of tetrahedra share all 4 oxygens in 3 dimensions to form a 3-D network If all tetrahedra are cored by silicon then there is no charge imbalance e.g., quartz If some tetrahedra are cored by Al, then the remaining charge balance achieved by bonding with cations e.g., feldspars

32. Framework Silicates (Tectosilicates) Is there a distinct shape to the crystal lattice? What shape will they take when they grow? Is there a difference in the bonds in different directions? What shape will they take when they break?

33. Framework Silicates

34. Mineral Particulates and Health Which type of silicate will most likely form fibrous particles when broken?

35. Mineral Particulates and Health Which type of silicate will most likely form fibrous particles when broken?Chain Silicates

38. Goldschmidt Classification A classification of the chemical elements into groups according to the part of the Earth where they tend to concentrate Lithophile elements form silicates or oxides and are concentrated in the crust (e.g., calcium, sodium, magnesium, chromium, titanium) Siderophile elements form alloys easily with iron and are concentrated in the core (e.g., iron nickel, cobalt, platinum, gold, tin) Chalcophile elements forms sulfide minerals if sufficient sulfur is available (e.g., copper, zinc, mercury, lead, arsenic, cadmium)

39. Mineral Particulates and Health Which group of elements tends to be most toxic? Which type of minerals will tend to house the most poisonous elements?

40. Mineral Particulates and Health Which group of elements tends to be most toxic?Chalcophile Which type of minerals will tend to house the most poisonous elements?Sulfides