2.  Compare this data to the data you collected in lab  Remember that this data is taken from the best samples available. Your student samples may not have been of the same quality, explaining some of the differences.

3.  Gray streak  Bluish Gray color  Metallic luster  Hardness 2-3  Cubic crystals/ 3 CP  Very dense  Lead ore

4.  White to yellow streak  (may not have left a streak for you)  Brown to black color  Non-metallic or sub-metallic luster  Hardness 3-4  Cleavage may be visible (6 directions)

5.  Greenish/black streak  Dull gold color  Metallic/sub-metallic luster  Hardness 3-4  Fracture  Looks somewhat like pyrite but is softer than pyrite

6.  Greenish/black streak  Brass, yellow, gold color  Metallic luster  Hardness 6-7  No cleavage, but cubic crystals visible  Very hard and brittle  Contains Fe but the presence of the S makes it too difficult to remove the Fe

7.  Reddish Streak  Reddish brown color  Non-metallic/earthy luster  Hardness 5-6  Fracture  Iron ore/important to Minnesota (iron range)

8.  Black Streak  Black/dark gray color  Sub-metallic to metallic  Hardness 5-7  Fracture  Naturally magnetic/ knows commonly as “lodestone”

9.  No streak/too hard  Dark gray to dark brown  Non-metallic/earthy?  Hardness 8-9  May observe 6 sided crystals  Extremely hard/used for grinding and jewelry(emerald, sapphire,ruby)

10.  Dark Streak (maybe dark red)  Dark gray to black color  Metallic to sub-metallic  Hardness 5-7  Fracture  Very dense  Iron ore (important in MN)

12.  Colorless streak  White to light gray color  Non-metallic luster  Hardness 6-7  Cleavage in 2 directions  Common in igneous rocks (especially granite)

13.  White Streak  Pinkish color  Non-metallic  Hardness 6-7  Cleavage in 2 directions  Common in igneous rock (granite especially)

14.  May show a colorless streak or none at all  Colorless in thin sections, brownish in thicker pieces  Non-metallic/glassy  Hardness 2-3  Cleavage in one directions (flakes)  Common in granite

15.  Colorless or no streak  Black color  Non-metallic/glassy  Hardness 2-3  One cleavage plane  Very thin sheets/flakes

16.  Colorless or white streak  Color is white/light gray  Non-metallic/waxy  Hardness One (1)  1 Cleavage plane but virtually impossible to see  Very soft, greasy feel

17.  Greenish-black streak  Dark green to black color  Non-metallic luster  Hardness 5-6  Long slender crystals  Common in Igneous rocks

18.  White to light green streak  Yellow green color  Non-metallic luster  Hardness 6-7  Granular  Common in Igneous rocks

19.  Colorless streak  Color varies  Non-metallic/glassy  Hardness 6-7  Many uses(jewelry, counter tops, glass making)  Sand is mostly quartz (SiO2)

20.  Greenish-gray streak  Greenish-gray color  Non-metallic  Hardness 5-6  2 planes of cleavage  Common in igneous rocks

22.  White Streak  Variety of colors (green, red, brown)  Non-metallic luster  Hardness 4-5  Crystals may be visible  Used in making fertilizer

23.  Colorless Streak  Translucent (light can go through it)  Non-metallic (glassy)  Hardness 2-3  Cubic crystals (3 CP @ 90 degrees)  Forms from evaporation of H2O with salt dissolved in it.  It’s salt!!!!

24.  White Streak  Color varies  Non-metallic  Hardness 3-4  May show cleavage in 4 directions, but it is really hard to see.  Used to make hydrofluoric acid (nasty stuff!)

25.  Yellow streak  Yellow color  Non-metallic  Hardness 1-3  Fracture  Smells like rotten eggs, used in making sulfuric acid, matches, fireworks.

26.  White Streak  Color varies  Non-metallic/glassy  Hardness3-4  3 cleavage planes, not at right angles  Reacts with acid (HCl) and if clear enough, will show double refraction  Commonly found in limestone, will naturally act to buffer acid precipitation

27.  White streak if any  Color varies, but mostly reddish brown and white  Non-metallic/earthy  Hardness 1-3  Fracture  Ore of aluminum.  Technically, bauxite is a rock that contains minerals

28.  White streak  White/light gray color  Non-metallic  Hardness 2  1 cleavage plane (may be hard to see)  Used to make sheet rock and plaster of paris  If forms from evaporation of water containing the mineral.

29.  Gray/black streak  Gray/black color  Metallic luster  Hardness 1-2  1 cleavage plane, but you may not see it  Very soft, greasy feeling. Pure carbon. Used for pencils and lubricants  “You can lead a horse to water, but a pencil is never lead!”