Chapter 2 Minerals

Minerals

1. A mineral is an inorganic (not formed from living things), solid material found in nature that has a definite crystal structure. There are 4000 different minerals, most of which are made up from a combination of only 8 elements.

2. Rocks are usually made up of two or more minerals.

Dietary Minerals • any of a group of inorganic elements that are

essential to humans and animals for normal body function.

• Dietary minerals are derived from the earth's crust. Plants extract the minerals from the soil, and humans and animals, in their turn, consume the plants.

• Calcium, Phosphorus, Magnesium, Sodium, Chlorine, Potassium, Sulfur, Iron, Cobalt, Chromium, Copper, Fluorine.

• http://nutrition.about.com/library/bl_minerals_quiz.htm

Mineral Formation

Minerals form in many different ways.- melted rock inside the earth (magma).- melted rock that reaches the earths surface (lava).-evaporation of water leaving minerals behind. (ocean water, salt in cup after ocean water evaporates) - precipitation of minerals suspended in water. (manganese nodules in ocean)

Properties of Minerals

Physical properties are identifiable items such as color, size, and texture; things that can be observed or measured without changing or attempting to change the material.

1. Crystals are solid minerals that have an orderly pattern of atoms. Crystal size and shape are very important identifying physical properties.

2. Cleavage and fracture is another clue to a minerals identity. In the way the mineral breaks defines what type of mineral it might be.

Cleavage - split into pieces with smooth, regular planes that reflect light.

Fracture – mineral that breaks into pieces with jagged or rough edges

3. Color – offers a valuable way to identify mineral. Color can also be confusing, for example fools gold (pyrite) has the same color as real gold.

4. Streak and luster – Streak is when a sample is scraped across an unglazed, white tile, called a streak plate. Based on the color of the streak left on the plate you can better identify the mineral.Luster is how shiny, dull, or pearly a mineral is, based on how it reflects light.

Hardness – minerals can be separated by how hard they are. This is done by doing a scratch test using the Mohs scale of hardness.

Density– The amount of matter in a given space. Mass per unit of space.(heft) is how heavy a rock is compared to an equal amount of water.

Common MO MineralsGalena (lead) CopperFire Clay Barite

Lime ZincCement Iron Oxide

Gemstones – are minerals that are rare and can be cut and polished, giving them a beautiful appearance.

Ores – minerals that can be sold for a profit.

Rock cycle – the continuous changing of rocks from one kind to another over a long period of time

Rocks

1. Igneous Rock – form when melted rock from inside Earth cools.

a) Extrusive igneous – melted rock cools on the Earth’s surface. Small

crystal sizesEx. Basalt

b) Intrusive Igneous - Melted rock that cools below Earth’s surface. Larger crystal sizes

Ex. Granite

Classifying igneous rocks

1. Crystal size

- fine grained crystals

- coarse grained crystals

- porphyritic (large and small crystals)

2. Mineral composition

- light colored

- dark colored

3. Metamorphic Rocks – New rocks that form when existing rocks are heated or squeezed. (Metamorphic means to change form)Granite to gneiss

two types Foliated gneissNonfoliated marble

2. Sedimentary Rocks – Pieces of broken rock, shells, mineral grains, and other materials that collects in layers to form rock.

Detrital sedimentary rock – fragments of weathered rocks compacted and cemented together. Conglomerate, sandstone, siltstone, and shale are forms of detrital rock. From coarse pebbles to fine clays. Classified based on sediment size that forms the rock.

Chemical sedimentary rocks – formed when dissolved mineral come out of solution. Calcium carbonate is carried in solution in ocean water When calcium carbonate comes out of solution as calcite and many crystals grow together forms limestone.

Organic sedimentary rocks – rocks made of the remains of once-living things. Chalk is an organic rock made of microscopic shells. Fossils are the major makeup organic rock.