Minerals of the
Earth’s Crust
Chapter 5
Earth Science
What is a Mineral?
 Basic material of the Earth’s crust
 Natural, inorganic, crystalline solid


(organic- made up of living things or the
remains of living things.
inorganic- not made up of living things or the
remains of living things.)
How do you determine a Mineral?
 Four basic questions to determine (Need yes
to all):
1. Is the substance inorganic?
2. Does the substance occur naturally?
3. Solid or crystalline form?
4. Definite chemical composition?
Kinds of Minerals
 There are over 3,000 types of minerals. Only
20 of them are common.
 Only a few make up 90% of the Earth’s crust:
quartz, orthoclase, plagioclase, muscovite,
biotite, calcite, dolomite, halite, gypsum, and
ferromagnesian (olivines, pyroxenes, and
amphiboles.)
 All minerals are classified into two major
groups based on their chemical composition:
silicate and nonsilicate.
 Silicates make up over 96% of the Earth’s
crust.
Silicate Minerals
 All silicates contain atoms of silicon (Si) and
oxygen (O).
 For example, quartz, contains silicon and
oxygen.
 Most silicates contain one or more different
kinds of elements.
 Feldspars are the most common silicates.
Nonsilicate Minerals
 Make up 4% of the Earth’s crust.
 Do not contain silicon.
 Six major groups: carbonates, halides, native
elements, oxides, sulfates, and sulfides.
Crystalline Structure
 All minerals have a crystalline structure. A
crystal is a natural solid with a definite shape.
 Scientists look at the crystalline shape to help
determine what type of mineral it is.
Part 2: Identifying Minerals
 Earth scientists, called mineralogists, conduct
tests to determine the types of minerals.
 Characteristics of minerals: color, luster
(metallic and nonmetallic), streak, cleavage
and fracture, hardness (scratch test), crystal
shape, and density.
 Mineral hardness: Mohs Hardness Scale.
-softer minerals are assigned a value of one,
for example talc is very soft.
-harder minerals are assigned a value of ten,
for example diamond is very hard.
 Density = mass divided by volume
Special Properties of Minerals
 Magnetism
 Fluorescence and Phosphorescence
 Double Refraction
 Radioactivity