1. Mineral Formation
6th Grade

2. Popcorn Rock Activity
When the rock dolomite is doused in white distilled vinegar, aragonite crystals slowly form

3. A similar process occurs in Yellowstone National Park and in the Carlsbad Caverns in New Mexico

4. Carlsbad Caverns, New Mexico

5. Stala…WHAT?!
StalagMITE = on the ground –mighty and tall StalacTITE = hanging from the ceiling –hanging tight to the ceiling

6. These form similarly to the “popcorn rock”
Acid rain or water from other sources reacts with the rock such as limestone or dolomite
This reaction hardens into a mineral
“Popcorn rocks” appear on cavern walls, such as at the Lehman Caves

7. Lehman Caves

8. Crystals that often form from water added to rock are usually calcite and aragonite

9. What are 3 ways that minerals form?
1) form by magma and lava cooling
2) form by hot water solutions
solutions: elements and compounds that are mixed with water
3) form by solutions evaporating

10. What is this called?

11. Geode = a rounded, hollow rock that is often lined with mineral crystals

12. Geode: How is it formed?

13. Formed when….
1) a cavity forms in a rock –(an open space, similar to a shell) –usually happen with rocks that are made from lava (the empty space is the gas bubbles)

14. Geode –crystals form when water containing dissolved minerals seeps into a crack or hollow in a rock

15. Minerals from Solutions
Solution: a mixture in which one substance is dissolved in another

16. 1) Minerals formed from Evaporation
Minerals form when solutions evaporate
Ex. If you stir salt crystals into a beaker or water, the salt dissolves, forming a solution. Eventually the solution evaporates, leaving behind salt crystals
Ex. mineral halite formed over millions of years when ancient seas slowly evaporated
This happens in the US along the Midwest, Southwest, and along the Gulf Coast

17. Halite –we use it in every day life!

18. Halite = table salt

19. Minerals formed from evaporation --gypsum

20. Minerals that can be formed by evaporation --Calcite

21. 2) Minerals from Hot Water Solutions
Deep underground, magma heats water to a high temperature
When the water solution begins to cool, the elements and compounds leave the solution and crystalize as minerals
Often PURE metals are formed this way

22. Minerals from Hot Water Solutions
Vein = a narrow channel or slab or a mineral that is different from the surrounding rock

23. Gold Vein

24. Remember that PURE METALS tend to form from hot water solutions underground, forming veins
Ex. Gold, Silver, Platinum

25. Platinum Luster: metallic Fracture: hackly Hardness: 4.5
Streak: silver-grey
Cleavage: none

26. Silver Luster: metallic Fracture: hackly Hardness: 2.5 – 3
Streak: silver-white
Cleavage: none

27. 3) Minerals formed from magma and lava:
As hot magma cools inside the crust
As lava hardens on the surface
*When liquids cool to a solid state, they form crystals.
Tourmaline: a mineral that forms as magma cools deep beneath the surface
What influences the size of crystals?

28. The size of crystals depend on:
The rate at which magma cools
The amount of gas the magma contains
The chemical composition of the magma
Magma closer to the surface cools FASTER (smaller crystals)
Magma deep within the crust cools SLOWLY (bigger crystals)

29. The size of a mineral depends on whether its high or low in the crust
Large crystals –deep within the crust
Small crystals --near the surface

30.
Take a look!