2. Aim: How can we identify minerals?
Do Now: Define “inorganic” and give an example.

3. Describe 2 observations about the following minerals

4. How can we use color to identify minerals?
1. Color - Actual color, visible to the naked eye
Easiest to use  not reliable
halite and calcite
Minerals can have the same color
ex. halite and calcite
Minerals can have more than one color
ex. Quartz
Some minerals have a characteristic color
ex. Pyrite (fools gold) is usually a brassy yellow (goldish color)
Quartz
Pyrite

5. How can we identify the luster of a mineral?
2. Luster: the way light is reflected off the minerals surface
Metallic – Its looks like a metal!!!! (very shiny)
Nonmetallic – looks glassy, glossy, greasy, waxy, pearly, or earthy (doesn’t look like a metal)

6. How can we identify the streak of a mineral?
3. Streak: True Color of a mineral, in its powdered form when rubbed on a streak plate
Usually a different color from the color of the mineral
Pyrite  blackish streak Hematite  red-brown streak
***Excellent way to identify minerals***

7. How can we identify the hardness of a mineral?
4. Hardness: the resistance a mineral offers to being scratched (not broken)
Done by scratching an unknown mineral with other substances whose hardness is known.
Glass = hardness of 5.5
Mineral scratches glass = harder than 5.5
Mineral does not scratch glass = softer than 5.5.
Mohs Hardness Scale

8. How can we determine if a mineral cleaves?
5. Cleavage: when a mineral breaks along flat or smooth surfaces due to the internal arrangement of atoms
Mica – one direction (sheets)
Halite – 3 directions (cubic)
Calcite – 3 directions, not at 90°
(rhombohedral)
Feldspar – 2 directions at 90º

9. How can we determine if a mineral fractures?
6. Fracture: mineral breaks along uneven surfaces
Does not follow the atomic arrangement
Rough, chunky blocks, or pieces
Quartz Sulfur Olivine

10. How can we use specific gravity (density) to identify a mineral?
7. Specific gravity – the density of a mineral compared to the density of water.
Minerals differ in density
All these physical properties are due to the
Internal Arrangement of Atoms!!!!!!!!

11. Chemical Properties Used To Identify Minerals
Acid test - mineral reacts
with hydrochloric acid and bubbles
ex. Calcite (CaCO3)
Dolomite is a mineral that reacts with HCl only when it is in powdered form.

12. Other Useful Tests 1. Double Refraction: Calcite
2. Taste – Halite (salt)
4. Iridescences: Labradorite
3. Smell – Sulfur (rotten eggs)
5. Fluorescence: certain minerals "glow“ when exposed to ultraviolet light
6. Magnetism: use a magnet to determine if the mineral is magnetic - magnetite

13. Summary Describe the tests used to identify a mineral.
How are cleavage and fracture different?
Why is color not a reliable test for identifying a mineral?
Describe the difference between metallic and non-metallic luster.
What is the name of the mineral that has a hardness of 7, has fracture and a white streak?
What mineral is usually identified by using the acid test? Explain what happens.
Why is a streak a more reliable property than color in mineral identification?

14. What is the name of the mineral that is nonmetallic, has a hardness of 7, has fracture, many possible colors, and is used in jewelry?
What is the name of the mineral that can be scratched by quartz and bubble with acid?
What is the name of the mineral that has a hardness of 5.5, metallic luster and has a black streak and is used to make steel?

15. How do we test the physical property of minerals?
Physical Properties of Minerals
Identification Tests:
Luster (metallic or non-metallic)
Hardness (1-10)
Cleavage or Fracture (How it breaks)
Streak (color of powder)
Density (specific gravity)
Color (least reliable)
These physical properties are due to the
Internal Arrangement of Atoms!!!!!!!!