Minerals

1. Minerals

2. Content Standards Addressed

3. Definition of a mineral: • Natural, inorganic solid • Possess an orderly internal structure of atoms (a.k.a. crystal lattice) • Has a definite chemical composition

4. Mineraloid – lacks an orderly internal structure Amber (Succinite - fossilized tree resin) Jet (Very Compact Coal) lechatelierite (Nearly Pure Silica Glass) Limonite (A Mixture of Oxides) Mercury (A Liquid at Normal Temperatures) Obsidian (Volcanic Silica Glass) Opal (Hydrated Silica) Pearl (Organicly Produced Carbonate) Tektites (Meteoritic Silica Glass)

5. Amber Image source Banded Opal Image source Tektite Image source Chalcedony, var. Jasper Image source

6. Polymorph – same chemical composition but form different crystalline structures Image source

7. Elements Basic building blocks of minerals Over 100 are known (92 naturally occurring)

8. source

9. Atoms Smallest particles of matter Retain all the characteristics of an element Virtual Experiment on the Bohr Atom

10. Chemical bonding Formation of a compound by combining two or more elements • Ionic • Covalent • Metalic

11. Ionic bonding Atoms gain or lose outermost (valence) electrons to form ions Ionic compounds consist of an orderly arrangement of oppositely charged ions Image source

13. Covalent bonding Atoms share electrons to achieve electrical neutrality (stronger than ionic bonds) Both ionic and covalent bonds can occur in the same compound Image source

14. Metallic bonding Valence electrons are free to migrate among atoms Weaker and less common Image source

15. Isotopes and radioactive decay Mass number = sum of neutrons + protons in an atom Isotope = atom that exhibits variation in its mass number Unstable isotopes emit particles and energy in a process known as radioactive decay

16. Composition and Structure of Minerals Atoms are chemically bonded in an orderly array Forms a crystal lattice Determines the all of the properties of a mineral

18. CrystalSystems Image source

19. Rapid cooling – poor form Slow cooling – good form Physical properties of minerals Crystal form - External expression of the internal arraignment of atoms

20. Physical properties of minerals Crystals grow outward from a central “seed”. Crystal form is maintained until the edges meet

21. Physical properties of minerals Luster - Appearance of a mineral in reflected light Two basic categories Metallic Nonmetallic - vitreous, silky, dull, or earthy

22. Serpentine = Nonmetallic, Silky Olivine = Nonmetallic, Vitreous Pyrite = Metallic Luster

23. Physical properties of minerals Color - Highly variable within minerals due to slight chemical changes (Least reliable)

24. Physical properties of minerals Streak - Color of a mineral in its powdered form Helpful in distinguishing different forms of the same mineral

25. Physical properties of minerals Hardness - Resistance of a mineral to abrasion or scratching Mohs scale of hardness

26. Physical properties of minerals Cleavage -Tendency to break along planes of weak bonding Produces flat, shiny surfaces Described by resulting shapes Three examples of perfect cleavage – fluorite, halite, and calcite

27. Physical properties of minerals

28. Physical properties of minerals

29. Cleavage planes are repeated, like a series of steps. In hand sample, the crystal face (cleavage plane) is a single surface.

30. Sheet-like cleavage in micas

31. Fracture Specific gravity Other properties Taste Smell Elasticity Malleability Feel Magnetism Double Refraction Reaction to hydrochloric acid Physical properties of minerals

32. Rock-forming Minerals

33. Mineral groups: Silicates Most common mineral group silicon-oxygen tetrahedron = silicate (SiO4)-4 molecule

34. Common silicate mineral groups

35. Silicate Minerals – Single Tetrahedra • Olivine • High temperature Fe-Mg silicate • Individual tetrahedra linked together by iron and magnesium ions • Forms small, rounded crystals with no cleavage

36. Silicate Minerals – Single Chains of Tetrahedra • Pyroxene group • Silicate tetrahedron + Fe + Mg • Two distinctive cleavages at nearly 90° • Augite

37. Silicate Minerals – Double Chains of Tetrahedra • Amphibole group • Silicate tetrahedron + various ions • Two perfect cleavages exhibiting angles of 124° and 56° • Hornblende

38. Silicate Minerals – Sheets of Tetrahedra • Micas • Two types of mica are biotite (dark) and muscovite (light)

39. Silicate Minerals – 3-D Network of Tetrahedra • Quartz • No cleavage!

40. Silicate Minerals – 3-D Network of Tetrahedra • Feldspars • Most common minerals • 2 planes of cleavage at 90° • Includes: • Orthoclase (potassium feldspar) • Plagioclase (sodium and calcium feldspar)

41. Quartz, Feldspar and Biotite = Granite

42. Nonsilicate minerals 8% of Earth’s crust Common in sedimentary rocks Many industrial applications

44. Mineral resources Reserves are already identified deposits Ores are useful metallic minerals that can be mined at a profit Economic factors may change and influence a resource

45. Investigation & Experimentation

46. Kindergarten • Scientific progress is made by asking meaningful questions and conducting careful investigations. As a basis for understanding this concept and addressing the content in the other three strands, students should develop their own questions and perform investigations. Students will: • Observe common objects by using the five senses. • Describe the properties of common objects. • Describe the relative position of objects by using one reference (e.g., above or below). • Compare and sort common objects by one physical attribute (e.g., color, shape, texture, size, weight). • Communicate observations orally and through drawings.

47. First Grade • Scientific progress is made by asking meaningful questions and conducting careful investigations. As a basis for understanding this concept and addressing the content in the other three strands, students should develop their own questions & perform investigations. Students will: • Draw pictures that portray some features of the thing being described. • Record observations & data with pictures, numbers, or written statements. • Record observations on a bar graph. • Describe the relative position of objects by using two references (e. g., above and next to, below and left of). • Make new observations when discrepancies exist between two descriptions of the same object or phenomenon.

48. Second Grade • Scientific progress is made by asking meaningful questions and conducting careful investigations. As a basis for understanding this concept and addressing the content in the other three strands, students should develop their own questions and perform investigations. Students will: • Make predictions based on observed patterns and not random guessing. • Measure length, weight, temperature, and liquid volume with appropriate tools and express those measurements in standard metric system units. • Compare and sort common objects according to two or more physical attributes (e. g., color, shape, texture, size, weight). • Write or draw descriptions of a sequence of steps, events, and observations.

49. Second Grade • Scientific progress is made by asking meaningful questions and conducting careful investigations. As a basis for understanding this concept and addressing the content in the other three strands, students should develop their own questions and perform investigations. Students will: • Construct bar graphs to record data, using appropriately labeled axes. • Use magnifiers or microscopes to observe and draw descriptions of small objects or small features of objects. • Follow oral instructions for a scientific investigation.

50. Third Grade • Scientific progress is made by asking meaningful questions and conducting careful investigations. As a basis for understanding this concept and addressing the content in the other three strands, students should develop their own questions and perform investigations. Students will: • Repeat observations to improve accuracy & know that the results of similar scientific investigations seldom turn out exactly the same because of differences in the things being investigated, methods being used, or uncertainty in the observation. • Differentiate evidence from opinion & know that scientists do not rely on claims or conclusions unless they are backed by observations that can be confirmed. Compare and sort common objects according to two or more physical attributes (e. g., color, shape, texture, size, weight).