1. Minerals!
Minerals!

2. What are minerals?
Minerals are a category of substances
found in the earth, formed on or below
the surface.

3. Minerals must have the following traits:
Minerals are solid
(they have fixed shape and volume)
diamond

4. Minerals are inorganic (not living material)
not animal!
not plant!
emerald

5. Minerals are naturally occurring (not man-made)
natural emerald
natural ruby
synthetic emerald
synthetic ruby

6. Minerals are crystalline (form regular shaped chunks)
uncut diamond
natural quartz

7. Minerals have
definite chemical composition
(they are only made of certain elements)

8. Classifying minerals:
(how to tell them apart)
Density: how heavy it is for its size

9. Color: some minerals have more than one
color, but same chemical composition
The coloration of
corundum (sapphires)
is very different from
that of calcite!

10. Streak: the color left by the mineral
Some minerals leave unique streaks!

11. Luster: how it reflects light--
metallic, glassy, pearly, silky, earthy...

12. Cleavage/fracture: how easily it breaks,
how it breaks (smooth, jagged, square...)
Cleavage in four directions. Example: CALCITE

13. Other: reactivity, magnetic, conductivity, phosphorescence/glows
cauliflower calcite

14. Hardness: how resistant it is to scratching
talc flakes easily
diamonds can’t be scratched!

15. Friedrick Mohs created a Hardness Scale: 10 is hardest, 1 is softest.
He based it on 2 main scratch tests:
Can be scratched by:
Fingernail: soft, under 3
Copper: hardness of 3
Steel: hardness of 4-5
Can scratch:
Glass: hardness of 6
Steel: hardness of 7-9
Anything: hardness of 10

16. Moh’s Hardness Scale