WS – How Minerals are Concentrated into Ores2015

1. To mine the metal lead from a rock containing the compound mineral galena (made of lead sulfide), the galena has to be _______________ separated from the rock and then the lead has to be ___________________ extracted from the galena. This takes a lot of money!!

____ 2. Which is more valuable? a) an ore mineral or b) a gangue mineral3a. Minerals such as magnetite and chromite collect in the bottom of a magma chamber

because they are very _____________. [Topic 1]3b. Minerals such as olivine and pyroxene also collect at the bottom of a magma chamber

because they are ________ ______________________ minerals which solidify first.____4. As a magma chamber finishes cooling, hot water-loaded magma rich in rare, left-over minerals such as emerald and tourmaline solidify at the top of the chamber to form:

a) placer deposits b) pegmatite deposits c) baked zones [Topic 2]5. Huge 30 foot long crystals are possible in a pegmatite because the magma contains a lot

of hot _____________ and the metal ions are able to move around more easily.6. 14.5 million carats of diamonds were collected from a large circular pit in Kimberley,

South Africa, called the “Big Hole”. These diamonds probably formed deep in the mantle and collected in _______________ pipes during intensive Mesozoic volcanism. [Topic 3]

7. Volcanic pipes also bring olivine-rich peridotite ____________liths up from the mantle.8. During the early Pre-Cambrian, there were lava flows that contained pockets of pure

___________ metal, forming the massive ore deposits of Northern Great Lakes. [Topic 4]9. When the molten magma intrudes into hardened country rock, the heat from the molten

intrusion causes the country rock to undergo ______________ metamorphism. [Topic 5]

10. The charred edge of the country rock is heated so much it is called a “___________ zone”.11. At the edge of the zone, calcite-rich ___________stone is heated and recrystallizes to

form the metamorphic rock __________________, with large interlocking calcite crystals.12. Where the hot fluids of the magma chamber come in direct contact with the limestone,

the two rocks chemically react to form the exotic minerals of the ____________ zone.13. Closer to the surface, superheated ______________ solutions are injected into cracks in

the overlying country rock which become filled with hydrothermal __________. [Topic 6]

14. A lode is a ________________er, super-________ version of a hydrothermal vein.15. Name 2 important hydrothermal ore minerals: 1) _______________ 2) _____________

16. Besides deep underground and in the mountains, we find hydrothermal deposits forming deep underwater at “Black Smokers” along the _____ - __________ ____________. [6b]

17. Name two minerals that commonly form cavern deposits: 1) _________ 2) _________ [7]

18. Bauxite started out as an aluminum-rich silicate rock. What is removed from the bauxite by chemical weathering? _______________ [Topic 8]

____ 19. What metal can be extracted from ancient extensive sedimentary deposits? [Topic 9]

a) gold b) silver c) copper d) iron20. Is that metal still forming deposits on the ocean floor today? ________21. When two much CaCO3 is dissolved in warm, shallow sea water, it ___________________

out and piles up in thick layers of limestone. Is limestone still forming today? ________22. Minerals such as gypsum, borax and halite (rock salt) are left behind when seas and lakes

evaporate, so they are called __________________ deposits. [Topic 10]____ 23. If you want to find a placer deposit of gold nuggets, you should look in what part

of the stream channel? [Topic 11] a) Point Bar -inner bank of a meander b) Cut Bank - outer bank of a meander c) along either bank of the straightaway

24. Gold is a common placer deposit because it has a very ________ specific gravity (19.3).Diamonds aren’t all that heavy, but many diamonds are found as placer deposits because they are very __________ (H = 10 on the Mohs Scale) and don’t wear down very much.

25. The rich source vein for placer deposits up in “them thar hills” is called the _______ lode.Review / Analysis Questions

26. You are looking at a rock that contains a rich “stripe” of pyrite, sphalerite, galena and quartz crystals. This ore rock is probably from a __________________ __________. [6]

27 - 28: The Witwatersrand region of South Africa has a 2 – 3 billion year old rock formation that is loaded with sand, gravel, pebbles and gold nuggets:

27. One theory suggests that the heavy gold nuggets were probably concentrated at the edge of an ocean basin by the action of river currents and waves. This type of rock formation is called a _____________ deposit. [11]

28. Another theory suggests that the rock was already formed when superheated gold-rich water solutions rose up from below, filling in cracks and fissures in the overlying sand and pebble layer. This would make the formation a ______________________ deposit. [6]

29. 20 Mule Team Borax detergent is strip-mined from the floor of Death Valley, CA. This indicates that Death Valley is the dried-up remains of an ancient _____________. [10]

30. Drill core samples from the Mediterranean Sea floor show thick layers of gypsum dating back to 6 million years ago. This indicates that the Mediterranean Sea had completely ________________ 6 million years ago (and 68 more times over the next million years!)

Ore Environment Matching____ 31. Magma Body____ 32. Heavy Minerals collect here____ 33. Pegmatite Deposits____ 34. Bushveldt Layered Gabbro

(contains platinum and titanium)____ 35. Volcanic Pipe / Conduit____ 36. Where diamonds come to the

surface____ 37. Where you can find ancient

Lava rocks with pockets of pure copper

____ 38. Two places where heavy minerals____ such as chromite collect A

BB

B

BC

D

E

F

B

A

Ore Environment Matching II____ 39. Magma Body (Intrusion)____ 40. “Baked Zone” (Marble)____ 41. Country Rock (Limestone)____ 42. Skarn Zone (Garnets, Kyanite

other exotic minerals)____ 43. Hydrothermal Veins (with

Gold, Pyrite and Quartz)____ 44. Heavy gold nuggets and hard

diamonds collect here.____ 45. Evaporites (Halite and Gypsum)

form here when an ocean completely dries up (evaporates).

____ 46. Limestone forms here whencalcite (CaCO3) precipitatesfrom warm shallow ocean water [Hint: One letter is not used!!]

C

E

E

C

D

B

A74

A

C

E

B

F

JH

G

F