Chapter 20: Earth Materials Table of Contents Chapter 20: Earth Materials Section 20.1: Minerals

Composition of Earth’s Crust Minerals 1 Composition of Earth’s Crust The (A.) The orderly arrangement of a minerals atoms makes it crystalline

Minerals 1 Atom Arrangement Minerals (B1) break along planes that cut across relatively weak chemical bonds is called cleavage. If there are not weak chemical bonds the minerals break with fracture

Minerals 1 Atom Arrangement (B2) Bonds connecting atoms can have different strengths. Scratching occurs as bonds in atoms are broken. Minerals with higher hardness have stronger bonds between atoms.

Minerals 1 Hardness

Minerals 1 Luster and Streak (B3) Metallic luster minerals reflect light in a way that a polished metal surface might. (B3) Nonmetallic minerals do not shine like polished metals.

Minerals From Hot Water 1 Minerals From Hot Water Some minerals are produced from (C) hot water solutions rich in dissolved mineral matter.

Minerals 1 Minerals from Magma Molten rock material found inside Earth is called magma. (C.) As magma cools, atoms slow down and begin to arrange into an orderly structure.

Minerals 1 Minerals From Water (C) When water slowly evaporates, concentrated dissolved mineral may be left behind to form crystal.

Mineral Uses (D) Uses of common minerals Quartz—glass, watches, gems, concrete Graphite—pencils, lubricants Halite—food preservative, salt Calcite—optics, cement

Igneous Rocks 2 Nature of Magma The (A.) minerals in the rock depend on the chemical composition of the magma from which it formed.

Types of Magma (B) Granitic magma: contains quartz, light in color, on continents, Thick and slow moving due to the silica in the quartz. Andesitic magma: composition between granitic and basaltic. Basaltic magma: little quartz, more iron, dark color, thin and runny due to little silica. On ocean floor.

Texture The size of the mineral crystals in a rock is called the (C) texture. coarse: large minerals caused by slow cooling underground. Fine: small minerals due to fast cooling on the surface. Glassy: no individual mineral crystals due to instant cooling after a volcanic eruption.

Igneous Rocks 2 Effect of Gases Magma contains small amounts of (CD.) dissolved gases, such as, water vapor and carbon dioxide. They can produce air holes in an extrusive rock after the gases escape.

(E) Igneous Rocks 2 Extrusive Intrusive Formed from lava Formed on the surface Cools quickly Fine or glassy texture Small grains or no grains EX: rhyolite Pumice basalt obsidian scoria Intrusive Formed from magma Formed underground Cools slowly Coarse texture Large mineral grains EX: granite gabbro

Igneous Rock Composition Igneous Rocks 2 Igneous Rock Composition

Rocks From Surface Materials Sedimentary Rocks 3 Rocks From Surface Materials Rocks inside Earth are protected from surface conditions. (A) Rock exposed at the surface is attacked by the weather.

(B) Sedimentary Rock 3 Clastic (Detrital) Sedimentary Rocks 3 (B) Sedimentary Rock Clastic (Detrital) Formed from rock sediments on the surface Formed by compaction and cementation EX: Sandstone, shale conglomerate, breccia Chemical Formed by precipitation of minerals or evaporation of water. EX: Limestone

Organic (Biochemical) Formed from remains of living things Formed by compaction and cementation EX: coal, shell limestone

(A) Foliated Has visible layers EX: gneiss slate schist Nonfoliated Does not have visible layers EX: marble quartzite

Igneous sedimentary metamorphic Compaction & cementation Weathering & erosion Heat & pressure melting Weathering & erosion Weathering & erosion metamorphic Heat & pressure Igneous melting melting Cooling & hardening