MINERALS

1. MINERALS • Introduction • What Are They? • Atoms & Elements • Physical Properties & Identification • Mineral Groups

2. Minerals Introduction

3. GEOL 131: Minerals - Intro Eight Most Abundant Elements in Earth’s Crust

4. GEOL 131: Minerals - Intro

5. GEOL 131: Minerals - Intro Some of the Most Abundant Minerals in Earth’s Crust • Quartz • Feldspars • Micas

6. GEOL 131: Minerals - Intro Some of the Most Abundant Minerals in Earth’s Crust • Amphiboles • Pyroxenes • Olivine e

7. Minerals Minerals What Are They?

8. GEOL 131: Minerals – What Are They? Minerals Are: • Solid • Naturally occurring • Inorganic

9. GEOL 131: Minerals – What Are They? Minerals Have: • Well-defined chemical compositions • Well-ordered atomic structures

10. Minerals Atoms & Elements

11. All Minerals Are Made of Atoms GEOL 131: Minerals – Atoms and Elements

12. GEOL 131: Minerals – Atoms and Elements The Periodic Table of the Elements http://www.ptable.com/

13. Basic Structure of an Atom GEOL 131: Minerals – Atoms and Elements

14. Valence Shells GEOL 131: Minerals – Atoms and Elements

15. Atomic Bonds GEOL 131: Minerals – Atoms and Elements • Hold atoms together to make mineral crystals • Formed by electron interaction • Require filled valence shells

16. Atomic Bonds GEOL 131: Minerals – Atoms and Elements

17. Atomic Bonds GEOL 131: Minerals – Atoms and Elements

18. Chemical Composition of Minerals GEOL 131: Minerals – Atoms and Elements • Elements present and in what amounts • Well-defined: Limited or no variation • Described by mineral’s formula • Halite (salt): NaCl

19. Atomic Structure of Minerals GEOL 131: Minerals – Atoms and Elements • Arrangement of atoms • Well-ordered: Repeats in a regular pattern

20. Atomic Structure of Minerals GEOL 131: Minerals – Atoms and Elements • Arrangement of atoms QUARTZ

21. Atomic Structure – Diamond vs Graphite GEOL 131: Minerals – Atoms and Elements

22. Minerals Physical Properties & Identification

23. GEOL 131: Minerals – Physical Properties & Identification Physical Properties • Each mineral has a unique set of properties • Determined by mineral’s chemical composition and atomic structure • Properties are used to identify unknown minerals

24. GEOL 131: Minerals – Physical Properties & Identification Physical Properties Commonly Used in Identification • Color • Streak • Luster • Cleavage • Crystal habit • Striations • Hardness • Effervescence • Magnetism

25. Quartz GEOL 131: Minerals – Physical Properties & Identification COLOR • Easy to observe, but can be misleading • Impurities can produce different colors

26. GEOL 131: Minerals – Physical Properties & Identification STREAK • Color of powdered mineral • More reliable than “bulk” color Streak plate

27. GEOL 131: Minerals – Physical Properties & Identification LUSTER • How sample reflects light • Not the same as color NONMETALLIC luster METALLIC luster

28. GEOL 131: Minerals – Physical Properties & Identification LUSTER • How sample reflects light • Not the same as color Both of these minerals have a METALLIC luster

29. GEOL 131: Minerals – Physical Properties & Identification CLEAVAGE • How sample cleaves (breaks) • Always the same for a given mineral • Three aspects • Quality • Number of directions • Angle

30. GEOL 131: Minerals – Physical Properties & Identification CLEAVAGE QUALITY - None No cleavage: irregular breakage surface

31. GEOL 131: Minerals – Physical Properties & Identification CLEAVAGE QUALITY - Good Note “stair-step” pattern Good cleavage: somewhat regular breakage surface

32. GEOL 131: Minerals – Physical Properties & Identification CLEAVAGE QUALITY – Excellent/perfect Excellent cleavage: smooth breakage surface

33. GEOL 131: Minerals – Physical Properties & Identification # OF CLEAVAGE DIRECTIONS • A number • Only applies to good or excellent cleavage quality

34. GEOL 131: Minerals – Physical Properties & Identification # OF CLEAVAGE DIRECTIONS - One One smooth surface

35. GEOL 131: Minerals – Physical Properties & Identification # OF CLEAVAGE DIRECTIONS - Two Two non-parallel smooth surfaces

36. GEOL 131: Minerals – Physical Properties & Identification # OF CLEAVAGE DIRECTIONS - Three Three non-parallel smooth surfaces

37. GEOL 131: Minerals – Physical Properties & Identification # OF CLEAVAGE DIRECTIONS - Four Fluorite Four non-parallel smooth surfaces

38. GEOL 131: Minerals – Physical Properties & Identification CLEAVAGE ANGLE • Angle between cleavage surfaces 60-degree angle 90-degree angle 120-degree angle

39. GEOL 131: Minerals – Physical Properties & Identification CRYSTAL HABIT • How a mineral grows • Unusual to see well-formed crystals in nature • Need space to grow

40. GEOL 131: Minerals – Physical Properties & Identification CRYSTAL HABIT Well-formed crystal faces Poorly-formed crystals: not enough space

41. GEOL 131: Minerals – Physical Properties & Identification CRYSTAL HABIT • Don’t confuse a crystal face with an excellent cleavage surface • Crystal face – caused by growth • Cleavage surface – caused by breaking

42. GEOL 131: Minerals – Physical Properties & Identification STRIATIONS • Thin grooves on mineral’s surface • Can be hard to see From facweb.bhc.edu From www4.uwm.edu

43. GEOL 131: Minerals – Physical Properties & Identification HARDNESS

44. GEOL 131: Minerals – Physical Properties & Identification EFFERVESCENCE Dilute hydrochloric acid (HCl) If CO3 ion present, carbon dioxide bubbles will form: CaCO3(calcite) + 2HCl = H2O + CO2 + CaCl2

45. GEOL 131: Minerals – Physical Properties & Identification MAGNETISM • Some iron-rich minerals are magnetic Magnetite (Fe3O4) attracting a magnet

46. GEOL 131: Minerals – Physical Properties & Identification MINERAL IDENTIFICATION • Table or flowchart • Observation of unique properties • Narrow down possibilities

47. GEOL 131: Minerals – Physical Properties & Identification MINERAL IDENTIFICATION

48. GEOL 131: Minerals – Mineral Groups MINERAL GROUPS • Silicates (largest group) • Carbonates • Sulfates • Sulfides • Oxides • Halides • Native elements

49. GEOL 131: Minerals – Mineral Groups MINERAL GROUPS - Silicates • Largest group • 90% of Earth’s crust • Si and O atoms in a tetrahedron (pyramid)

50. GEOL 131: Minerals – Mineral Groups MINERAL GROUPS - Silicates • Oxygen atoms can bond to adjacent tetrahedra in a mineral’s atomic structure • Forms the “backbone” of the mineral • Example: single-chain structure • Each tetrahedron shares two oxygens with adjacent tetrahedra