Physical Properties Lecture Min Lab 1

1. Physical Properties LectureMin Lab 1 • Penelope Morton, University of Minnesota, Duluth • Jason Sturms, Graduate Student WVU • Helen Lang, Professor WVU • John Tellers, Graduate Student WVU • Travis Warner, Graduate Student WVU • All of the above people have compiled this PowerPoint presentation; JM edited 8/20/2010.

2. Some Colors of Quartz

3. Varieties of Hematite

4. Streak • Streak is the color of a mineral when finely powdered • Streak of a mineral is usually constant • Colored streaks are usually important • White streaks are generally unimportant • If no streak is left, that particular mineral is harder than the streak plate

5. Hardness • 6 – Orthoclase Feldspar • 7 – Quartz • 8 – Topaz • 9 – Corundum • 10 – Diamond • Mohs Hardness Scale: • 1 – Talc • 2 – Gypsum • 3 – Calcite • 4 – Fluorite • 5 – Apatite • Relative Scale: • 2.5 fingernail, aluminum • 3.5 penny, brass • 4.5 iron • 5.5 pocketknife blade, glass • 6.5 metal file, streak plate

6. Luster • The appearance of a mineral in reflected light. • Many variations of luster, but we will mainly use metallic, sub-metallic, and dull. • Metallic – Mineral looks like a metal (shiny). • Submetallic – A poor metallic luster. It reflects very little light. • Dull – Does not reflect light.

7. Examples of metallic luster

8. Example of submetallic luster

9. Example of dull luster

10. Cleavage • If a crystal breaks due to stress and the broken piece retains a smooth plane or crystal shape, the mineral has cleavage. • Cleavage surfaces often reflect light well, all at once in a single flash • Any mineral break that is not cleavage is termed a fracture. • Cleavage can be confused with crystal faces (how the mineral grows). • Crystal faces tend to form regular polygonal shapes, such as cubes and prisms.

11. #1 - Calcite • CaCO3 • Non-metallic • White, colorless, yellow, etc • Softer than penny, harder than fingernail (H ~ 3) • White Streak • Cleavage • Fizzes with acid

12. #2 - Galena • Metallic • Silver-gray • Hard as fingernail • Dark gray streak • Cleavage • Very Heavy

13. #3 - Feldspar • Non-metallic • Gray, blue, pink, white • Harder than glass • White streak • Cleavage • Fine striations (thin wavy lines)

14. #4 - Pyrite • Metallic • Brass Yellow • Scratches glass • Greenish-black streak • No cleavage • “Fool’s Gold”

15. #5 - Amphibole • Non-metallic • Black or dark green • Between 5-6 • Colorless streak • Cleavage

16. #6 - Muscovite • Non-metallic • Colorless • H ~ 2.5 • Colorless streak • Cleavage • Transparent thin, flexible sheets

17. #7 - Fluorite • Non-metallic • Many colors • Softer than glass • White streak • Cleavage • Fluorescent (glows in black light)

18. Additional Luster Examples • Vitreous • Gypsum • Resinous • Amber

19. Luster Cont. • Adamantine • Amber