Chapter 20 Notes

Name Date Class
Earth Materials 35
Section 1 Minerals
A. Only a few _______________ combine to form most of the common minerals in Earth’s crust.
B. _______________—a naturally occurring inorganic solid with a predictable chemical
C. The way minerals _______________ is determined by the arrangements of the atoms and the
bonds between them.
1. _______________—breakage along planes that results in a smooth, flat surface
2. _______________—irregular, uneven break
D. _______________ connecting atoms in minerals often have different strengths.
1. _______________—a mineral’s resistance to scratching
E. _______________—the way a mineral reflects light
1. _______________ luster minerals reflect light in a way that a metal surface might.
2. _______________ luster minerals shine like glass or appear earthy or waxy.
F. _______________ is the color of a mineral in powdered form.
G. Ways that minerals form
1. _______________ from hot-water solutions rich in mineral matter
2. _______________ from molten rock material
a. _______________—molten rock material found inside Earth
3. _______________ of water rich in dissolved salts at low temperatures near Earth’s surface
H. Mineral groups—About _______________ minerals have been identified in nature.
1. Some minerals are so common that they are called _______________ minerals.
2. _______________—most important minerals by volume of Earth’s crust
3. Carbonates, oxides, halides, sulfides, sulfates, and native metals are classified as
a. To be an _______________, a mineral must occur in large enough quantities to be
economically recoverable.
36 Earth Materials
Name Date Class
Section 2 Igneous Rocks
A. _______________ are naturally formed consolidated mixtures of minerals, rock fragments, or
volcanic glass.
1. _______________—a description that includes the size and arrangement of a rock’s
B. _______________ form from within or push into regions of Earth’s crust.
1. The _______________ of intrusive igneous rocks gives clues about where in Earth
they formed.
2. Texture
a. _______________—the size of individual mineral crystals in intrusive igneous rocks
3. Classification
a. Intrusive igneous rocks that are rich in quartz and contain alkali feldspar are called
_______________. Because of its _______________, granite is a dominant rock in
continental crust.
C. _______________—formed by the cooling of lava that has erupted at Earth’s surface
1. Textures
a. _______________—an extrusive rock in which cooling starts off slowly below the
surface with large crystals, but finishes at a faster rate to form small or no crystals
2. Effects of gases
a. Lava that flows across the surface can have many tiny holes, giving it a
_______________ texture.
Section 3 Sedimentary Rocks
A. _______________—form from fragments of other rocks
B. Types of sedimentary rock
1. _______________—sedimentary rock type composed mainly of clasts
a. _______________—means “to lessen or wear away”
2. _______________—form through activity of chemicals dissolved in water
a. _______________ is the crystallization of excess dissolved mineral material.
Name Date Class
Earth Materials 37
3. _______________ contain the remains of living organisms.
a. The hard parts, or _______________, of organisms are composed of calcium carbonate
and are cemented together by calcite mud.
b. _______________ is a carbon rock formed by compressed plant material.
Section 4 Metamorphic Rocks
A. Metamorphic rocks have been changed by some combination of _______________,
_______________, and _______________.
B. Agents of metamorphism—_______________, _______________, and _______________
1. Common active chemicals, _______________ and _______________, chemically react
with rock.
2. Some new minerals form by _______________ at higher temperature and pressure.
C. Environments of metamorphism
1. _______________—huge areas of changed rock caused by regional movements of large
parts of Earth’s crust and uppermost mantle
2. Local contact of any preexisting rock with magma is called _______________.
D. _______________ is used to identify the type of metamorphic rock.
1. _______________ rocks—lots of layers or bands
2. Nonfoliated include rocks whose grains are more uniform in _______________ and more
_______________ in orientation.
a. Mineral grains tend to _______________ as the grade of metamorphism increases.
E. Composition provides clues about the original rock _______________ and the
_______________ to which a rock has metamorphosed.
1. _______________—starting rock material
2. The starting rock material and the _______________ of metamorphism together control
the resulting metamorphic rock.
F. Processes of the _______________ include any chemical and physical conditions that continuously
form and change rocks.