Real-Life Applications: Economic Mineral Deposits

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Alicia Lang
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1 Real-Life Applications: Economic Mineral Deposits

2 Economic Minerals Economic minerals are minerals that can be extracted, processed and marketed for a profit. Various factors determine if a mineral is an economic mineral: Interest in mineral Size of deposit Mineral concentration Mineral depth below surface Market value

3 Ore An ore is a type of rock that contains minerals with important elements including metals. The ores, that are profitable, are extracted through mining; these are then refined to extract the valuable element(s). Iron ore

4 Ores Lead Ore Gold Ore

5 Economic Mineral Deposits There are 5 types of economic mineral deposits: Magmatic Hydrothermal Placer Secondary Enrichment Metamorphism

6 Economic Mineral Deposits 1. Magmatic Many of the world s most valuable metallic mineral resources are directly associated with magma that ultimately forms igneous rocks. Certain metals are naturally enriched in certain magmas, but most only reach economically viable concentrations upon further enrichment during the cooling process.

7 Magmatic Two specific types of magmatic deposits we will look at are: a. Gravitational b. Dissemination (Magma source hydrothermal)

8 a. Gravitational A straightforward method, some economically important minerals are concentrated by simple gravitational settling within a magma chamber. In essence, crystals of heavy minerals that form during early stages of crystallization settle at the bottom of a magmatic body.

9 a. Gravitational High-density minerals such as chromites and magnetite crystallize during the early stages of magma crystallization. The crystals can sink to the bottom of the magma chamber, forming concentrated layers of these minerals.

10 Must be able to draw and explain this:

11 b. Disseminated Hydrothermal fluids (from hydrothermal vents produced by volcanism - from magma) cause ores to accumulate. These ores are distributed and accumulate in small masses throughout a permeable (can pass through) large rock body.

12 disseminated deposits

13 2. Hydrothermal Hydrothermal vents also cause vein deposits Among the best-known and most important ore deposits are those generated from hydrothermal (hotwater) solutions, Likely produced during the late-stage cooling of magma, by the heating of groundwater or seawater, or by metamorphic processes.

14 2. Hydrothermal The deposits are forming where heated seawater, rich in dissolved metals and sulphur, gushes from the seafloor as clouds called black smokers. Vein Deposits : Hydrothermal fluids from cooling magmas can rise to the surface through fractures, faults, (from the brittle deformation) of the overlying rocks. Fluids passing through the fractures eventually cool, allowing minerals to precipitate

15 Hydrothermal Deposits at Black Smokers

16 Hydrothermal Vein Deposits Gneiss laced with quartz veins at Diablo Lake Overlook, North Cascades National Park, Washington.

17 Must be able to draw and label this: (not in 3D)

18 3. Placer Deposits The formation of placer deposits relates to the sorting action of running water. Mineral particles of high density can be concentrated due to the sorting out and washing away of mineral particles of lower density Examples: Gold, Platinum and Diamonds

19 3. Placer Deposits Must be able to draw and label this:

20 4. Secondary Enrichment Many rocks have ores scattered throughout (but would not be valuable to mine) Weathering can concentrate these minor amounts of ores into economically valuable concentrations. This is basically sedimentation of the rocks, then (usually water will carry and deposit the ores in a single location)

21 4. Secondary Enrichment Example: Bauxite Principal ore of aluminum Forms in rainy tropical climates from chemical weathering and the removal of undesirable elements by leaching

22 5. Metamorphism Many of the most important metamorphic ore deposits are produced by contact metamorphism. Here the host rock is re-crystallized and chemically altered from heat, pressure, and hot chemical fluids. (metamorphism) Examples: zinc, lead, copper and iron.

23 Must be able to draw and label this: Skarn are the metal-rich deposits

Figure 1.2. Growth of the world s population through history. Notice the sharp drop due to the Black Death that struck Europe in 1348, and the sharp

Figure 1.2. Growth of the world s population through history. Notice the sharp drop due to the Black Death that struck Europe in 1348, and the sharp rise that occurred in the nineteenth and twentieth centuries.